Introduction

ST Joint Kinematics

Arthrokinematics

Integrated Function

Postural Dysfunction

Shoulder Dysfunction Relative to Predicitive Models of Dysfunction

Techniques and Ending Info

Bones, Articulating Surfaces and Joint Types

Palpation

Capsule, Ligaments, and Menisci

Bursae

Nerves

Osteokinematics

SC Joint Kinematics

AC Joint Kinematics

Sternoclavicular (SC), Acromioclavicular (AC), and Scapulothoracic (ST) Joint Anatomy

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Sternoclavicular, Acromioclavicular, and Scapulothoracic Joint Anatomy

Sternoclavicular, Acromioclavicular and Scapulothoracic Joints

This course describes sternoclavicular joint anatomy (SC joint), acromioclavicular joint anatomy (AC Joint), and scapulothoracic joint anatomy (ST joint). These are the joints resulting from the approximation of the sternum (breastbone) with the <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> clavicle (collar bone), the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> clavicle with the scapula (shoulder blade), and the scapula with the rib cage. These joints are also referred to as the shoulder girdle, and most often analyzed by referring to motion of the scapula. This course includes descriptions of the bones, synovial joints, joint actions, ligaments, bursae, relative location, the relationship between the bones of the clavicle, sternum, acromion, and thoracic spine, and the muscles that cross them. Further, this course discusses palpation and introduces sternoclavicular, acromioclavicular, and scapulothoracic joint (upper limb) <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> exercises, manual techniques, and interventions for dysfunction, pain, <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>, and <a id="movement-impairment" data-tip="1575" target="_blank" href="/glossary-term/movement-impairment" class="glossary">movement impairment</a>. The SC, AC, and ST joints often play a role in common <a id="movement-impairment" data-tip="1579" target="_blank" href="/glossary-term/movement-impairment" class="glossary">dysfunctions</a> and joint injuries of the shoulder including upper crossed syndrome, rounded shoulder <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>, upper body dysfunction (UBD) (e.g. impingement syndrome), cervical spine dysfunction, forward head <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a> (e.g. chronic neck pain), thoracic spine dysfunction and thoracic kyphosis (e.g. upper back pain), sternocostal dysfunction and stiffness (e.g. costochondritis), and elbow dysfunction (e.g. <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> epicondylitis). Sports medicine professionals (personal trainers, fitness instructors, physical therapists, massage therapists, chiropractors, occupational therapists, athletic trainers, etc.) with advanced knowledge of the sternoclavicular, acromioclavicular, and scapulothoracic joints will improve their ability to analyze human movement and develop sophisticated exercise programs and therapeutic (rehabilitation) interventions. Further, this course is essential knowledge for future courses discussing injury prevention and physical rehabilitation/physical therapy (e.g. <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> and treatment of joint injury, joint separation/dislocation, shoulder pain, shoulder separation, rotator cuff injury, type II acromion, ac joint sprain, and upper limb pain), the effect the SC, AC, and ST joints have on upper extremity (upper limb) and cervical spine alignment (e.g. a forward head position), and active and passive exercises for the shoulder girdle, including techniques to enhance sports performance (e.g. upper limb <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a>, strength, hypertrophy, and <a id="power" data-tip="1399" target="_blank" href="/glossary-term/power" class="glossary">power</a>).
<h4>Brookbush Institute&apos;s most recommended techniques for the SC, AC, and ST joints (see videos below):</h4>
<ul>
 <li>
 <h4> Assess: </h4>
 <ul>
 <li><a href="https://brookbushinstitute.com/video/acromioclavicular-ac-joint-cross-body-test">Acromioclavicular (AC) Joint Cross Body Test</a></li>
 </ul>
 <a href="https://brookbushinstitute.com/video/deep-cervical-flexor-endurance-test"> </a>
 </li>
 <li> Self-administered Techniques:
 <ul>
 <li> Release: <a href="https://brookbushinstitute.com/video/levator-scapulae-sa-static-release">Levator Scapulae</a></li>
 <li>Stretch: <a href="https://brookbushinstitute.com/video/levator-scapula-sa-static-stretch">Levator Scapula Static Stretch</a></li>
 <li> Activation: <a href="https://brookbushinstitute.com/video/serratus-anterior-isolated-activation-2">Serratus Anterior</a></li>
 </ul>
 </li>
 <li>Manual Techniques:
 <ul>
 <li> Release: <a href="https://brookbushinstitute.com/video/pectoralis-minor-static-manual-release">Pectoralis Minor</a></li>
 <li> Mobilization: <a href="https://brookbushinstitute.com/video/thoracic-spine-mobilization-posterior-anterior-transverse">Thoracic Spine Mobilization: Posterior-to-Anterior</a></li>
 <li> Manipulation: <a href="https://brookbushinstitute.com/video/cervicothoracic-junction-manipulation">Cervicothoracic Junction Manipulation</a></li>
 </ul>
 <a href="https://brookbushinstitute.com/video/cervicothoracic-junction-manipulation"> </a>
 </li>
</ul>
<img title="The acromioclavicular joint, joint capsule, ligaments, and cartilage surrounding the scapula" src="https://www.datocms-assets.com/25800/1644946758-shoulder_distal_clav_osteolysis_anatomy04.jpeg" alt="Cross section of the AC joint">

Course Description: Shoulder Girdle Anatomy: Sternoclavicular Joint (SC), Acromioclavicular Joint (AC), and Scapulothoracic Joints (ST)

<h2>What&apos;s in a name</h2>
<ul>
 <li><a href="http://www.etymonline.com/index.php?term=sternum&amp;allowed_in_frame=0" target="_blank" rel="noopener noreferrer">Sternum (n)</a>: &quot;breastbone,&quot; 1660s, from Greek sternon &quot;chest, breast, breastbone&quot; (in Homer, only of males), also &quot;the breast as the seat of affections,&quot; related to stornynai &quot;to spread out,&quot; from PIE *ster-no- &quot;to stretch, extend,&quot; from root *stere-, *ster- &quot;to spread,&quot; related to stornynai &quot;to spread out&quot; (see <a class="crossreference" href="http://www.etymonline.com/index.php?term=structure&amp;allowed_in_frame=0" target="_blank" rel="noopener">structure</a> (n.)), on the notion of the chest as broad and flat, as opposed to the neck. Related: Sternal.&quot; (<a href="http://www.etymonline.com/index.php?term=sternum&amp;allowed_in_frame=0" target="_blank" rel="noopener noreferrer">Etymology Online</a>)</li>
 <li><a href="http://www.etymonline.com/index.php?allowed_in_frame=0&amp;search=clavicular" target="_blank" rel="noopener noreferrer">Clavicular (n)</a>: &quot;&quot;collarbone,&quot; 1610s, from Middle French clavicule &quot;collarbone&quot; (16c.), also &quot;small key,&quot; from Medieval Latin clavicula &quot;collarbone&quot; (used c.980 in a translation of Avicenna), special use of classical Latin clavicula, literally &quot;small key, bolt,&quot; diminutive of clavis &quot;key&quot; (see <a class="crossreference" href="http://www.etymonline.com/index.php?term=slot&amp;allowed_in_frame=0" target="_blank" rel="noopener">slot</a> (n.2)); in the anatomical sense a loan-translation of Greek kleis &quot;key, collarbone.&quot; So-called supposedly from its function as the &quot;fastener&quot; of the shoulder. Related: Clavicular.&quot; (<a href="http://www.etymonline.com/index.php?allowed_in_frame=0&amp;search=clavicular" target="_blank" rel="noopener noreferrer">Etymology Online</a>)</li>
</ul>
<h2 style="padding-left: 40px;"><a href="https://www.datocms-assets.com/25800/1642705599-clavicle.jpeg"><img src="https://www.datocms-assets.com/25800/1642705599-clavicle.jpeg" alt="An X-ray of the ribcage, vertebrae, scapula, and clavicle" title="An image of the clavicle and sternoclavicular joint"></a></h2>
<ul>
 <li><a href="http://www.etymonline.com/index.php?allowed_in_frame=0&amp;search=scapula" target="_blank" rel="noopener noreferrer">Scapula (n)</a>: &quot;shoulder blade,&quot; 1570s, Modern Latin, from Late Latin scapula &quot;shoulder,&quot; from Latin scapulae (plural) &quot;shoulders, shoulder blades,&quot; perhaps originally &quot;spades, shovels,&quot; on the notion of similar shape, but animal shoulder blades might have been used as scraping tools in primitive times, from PIE *skap-, <a id="isoform" data-tip="1277" target="_blank" href="/glossary-term/isoform" class="glossary">variant</a> of *skep- &quot;to cut, scrape&quot; (see <a class="crossreference" href="http://www.etymonline.com/index.php?term=scabies&amp;allowed_in_frame=0" target="_blank" rel="noopener">scabies</a>).&quot; (<a href="http://www.etymonline.com/index.php?allowed_in_frame=0&amp;search=scapula" target="_blank" rel="noopener noreferrer">Etymology Online</a>)</li>
 <li>Acromion (n): &quot;from the Greek akros, meaning topmost, highest&quot; (<a href="http://www.etymonline.com/index.php?term=acro-&amp;allowed_in_frame=0" target="_blank" rel="noopener noreferrer">Etymology Online</a>)</li>
 <li><a href="http://www.etymonline.com/index.php?term=thorax&amp;allowed_in_frame=0" target="_blank" rel="noopener noreferrer">Thorax (n)</a>: &quot;chest of the body,&quot; late 14c., from Latin thorax &quot;the breast, chest; breastplate,&quot; from Greek thorax (genitive thorakos) &quot;breastplate, chest,&quot; of unknown origin.&quot; (<a href="http://www.etymonline.com/index.php?term=thorax&amp;allowed_in_frame=0" target="_blank" rel="noopener noreferrer">Etymology Online</a>)</li>
 <li>Joint (n): &quot;c. 1300, &quot;an (anatomical) joint, a part of a body where two bones meet and move in contact with one another, the structure that holds such bones together,&quot; from Old French joint &quot;joint of the body&quot; (12c.), from Latin iunctus &quot;united, connected, associated,&quot; past participle of iungere &quot;join&quot; (see <a class="crossreference" href="http://www.etymonline.com/index.php?term=jugular&amp;allowed_in_frame=0" target="_blank" rel="noopener">jugular</a>). &quot; (<a href="http://www.etymonline.com/index.php?term=joint" target="_blank" rel="noopener noreferrer">Etymology Online</a>)</li>
</ul>
<a href="https://www.datocms-assets.com/25800/1642705644-clavicle.png"><img src="https://www.datocms-assets.com/25800/1642705644-clavicle.png" width="498" height="156" title="A superior view of the clavicle with attachments of the pectorlais major and SCM" alt="The clavicle with boney landmarks highlighted"></a>
Clavicle (<a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">Superior</a> View) - By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See &quot;Book&quot; section below) Bartleby.com: Gray&apos;s Anatomy, Plate 200, Public Domain, https://commons.wikimedia.org/w/index.php?curid=792173

Introduction to Shoulder Girdle Anatomy: Sternoclavicular Joint (SC), Acromioclavicular Joint (AC), and Scapulothoracic Joints (ST)

Palpation 

<h2>Non-contractile/passive tissue</h2>
<table>
 <tbody>
 <tr>
 <td>
 <h3>Name</h3>
 </td>
 <td>
 <h3>Attachments</h3>
 </td>
 <td>
 <h3>Course</h3>
 </td>
 <td>
 <h3>Restricted Motions</h3>
 </td>
 </tr>
 <tr style="background-color: #c7c7c7;">
 <td colspan="4">Sternoclavicular Joint</td>
 </tr>
 <tr>
 <td>Anterior capsular ligament</td>
 <td>
 <ul>
 <li>Clavicular Attachment: <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> inferomedial surface of the <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> end of the clavicle</li>
 <li>Sternal Attachment: <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> superolateral surface of the manubrium of the sternum</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Inferomedially</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Retraction</li>
 <li>Distraction</li>
 <li><a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">Superior</a> portion limits clavicular depression</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Posterior capsular ligament</td>
 <td>
 <ul>
 <li>Clavicular Attachment: <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> inferomedial surface of the <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> end of the clavicle</li>
 <li>Sternal Attachment: <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> superolateral surface of the manubrium of the sternum</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Inferomedially</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Distraction</li>
 <li><a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">Superior</a> portion limits clavicular depression</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Costoclavicular ligament
 <ul>
 <li><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> bundle</li>
 <li><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> bundle</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Sternal/Rib Attachment: 1st rib costal cartilage</li>
 <li>Clavicular Attachment: costal tuberosity on <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> clavicle</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Oblique with bands perpendicular to each other.</li>
 <li><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> bundle: superiorly and laterally</li>
 <li><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> bundle: superiorly and medially</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>All clavicle motions except depression</li>
 <li><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> bundle: retraction</li>
 <li><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> bundle: protraction</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Interclavicular ligament</td>
 <td>
 <ul>
 <li>Clavicular Attachment: <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> ends of the right and left clavicles</li>
 <li>Sternal Attachment: <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> portion of the manubrium</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Horizontally</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Clavicular depression</li>
 <li>Clavicular distraction</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Articular Disc</td>
 <td>
 <ul>
 <li>Sternal Attachment: <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> edge of clavicular facet on manubrium</li>
 <li>Clavicular Attachment: superiorly on the sternal end of the clavicle</li>
 <li>Other Attachment: interclavicular ligament, internal surface of the capsule</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Inferolaterally from clavicle to manubrium</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Functions as a shock absorber and increases the articular surface area</li>
 </ul>
 </td>
 </tr>
 <tr style="background-color: #c7c7c7;">
 <td colspan="4">Acromioclavicular Joint</td>
 </tr>
 <tr>
 <td>Acromioclavicular ligament (14): Superioposterior (SP) band (consistently well developed)</td>
 <td>
 <ul>
 <li>Scapular Attachment: <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> acromion</li>
 <li>Clavicular Attachment: <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> clavicle</li>
 </ul>
 Reinforced by the <a href="https://brookbushinstitute.com/article/deltoids" target="_blank" rel="noopener">deltoid</a> and upper <a href="https://brookbushinstitute.com/article/trapezius-muscle" target="_blank" rel="noopener">trapezius</a>
 </td>
 <td>
 <ul>
 <li>SP: obliquely at a 30&#xB0; angle to the joint surface - wraps around the <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> joint surface</li>
 </ul>
 </td>
 <td>
 <ul>
 <li><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> translation &amp; <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> rotation of the clavicle</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Acromioclavicular ligament (14):Anteriorinferior (AI) band (less well developed)</td>
 <td>
 <ul>
 <li>Scapular Attachment: <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> acromion</li>
 <li>Clavicular Attachment: <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> anteroinferior edge</li>
 </ul>
 *Significant variations exist in dissection.
 </td>
 <td>
 <ul>
 <li>AI: generally from the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> acromion to the anteroinferior edge of the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> clavicle.</li>
 </ul>
 </td>
 <td>
 <ul>
 <li><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> of the clavicle</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Coracoacromial ligament (15)
 <ul>
 <li>Superior</li>
 <li>Inferior</li>
 </ul>
 </td>
 <td>* Note: this ligament connects two parts of the scapula
 <ul>
 <li>Scapular Attachments: Anteroinferior acromion to the coracoid process</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Inferomedially</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Creates an arch under which the Supraspinatus tendon passes.</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Coracoclavicular ligament
 <ul>
 <li>Conoid ligament</li>
 <li>Trapezoid ligament</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Conoid ligament:
 <ul>
 <li>Scapular Attachment: <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">base</a> of coracoid process</li>
 <li>Clavicular Attachment: conoid tubercle</li>
 </ul>
 </li>
 <li>Trapezoid ligament:
 <ul>
 <li>Scapular Attachment: the <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> surface of coracoid process</li>
 <li>Clavicular Attachment: trapezoid line</li>
 </ul>
 </li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Conoid ligament: nearly vertically</li>
 <li>Trapezoid ligament: superolaterally</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Conoid ligament: <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> movement of the scapula on a fixed clavicle</li>
 <li>Trapezoid: <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> movement of the scapula on a fixed clavicle</li>
 </ul>
 </td>
 </tr>
 <tr>
 <td>Articular Disc (7)</td>
 <td>
 <ul>
 <li>Variable depending on individual and age.</li>
 <li>Variations range from complete discs to partial meniscoid to absent discs.</li>
 <li>Complete discs are typically found in younger subjects and absent discs in older subjects (although not always)</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>n/a</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Functions as a shock absorber and increases the articular surface area</li>
 </ul>
 </td>
 </tr>
 </tbody>
</table>
<a href="https://www.datocms-assets.com/25800/1642706295-acromioclavicular-ligaments-2.jpeg"><img src="https://www.datocms-assets.com/25800/1642706295-acromioclavicular-ligaments-2.jpeg" title="The shoulder joint, acromioclavicular joint, sternoclavicular joint, and ligaments" alt="The acromioclavicular joint, with boney landmarks and ligaments labeled"></a>
Acromioclavicular ligaments - source unknown

SC, AC, & ST Connective Tissue: Capsule, Ligaments, and Menisci

<h4>Major bursae associated with the Scapulothoracic (ST) Joint (consistently observed on imaging and dissection):</h4>
<ul>
 <li>Scapulothoracic or infraserratus bursa: Located in the triangular space between the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> and the chest wall. Reduces friction between the soft tissue of the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> and the bony tissue of the thorax during upper extremity and scapula motion.</li>
 <li>Subscapularis or supraserratus bursa: Located in the triangular space between the <a href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">subscapularis</a> and the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterio</a>r, deep to the midpoint of the spine of the scapula. Reduces friction between these muscles (<a href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">subscapularis</a> and <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> on the scapulothoracic articulation).</li>
</ul>
<h4>Additional minor bursae associated with the scapulothoracic articulation (inconsistently observed on imaging and dissection) (16-19):</h4>
<ul>
 <li>Trapezoid bursa: Located between the <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">trapezius</a> and at the root of the spine of the scapula, reducing friction between the trapezius muscles and this bony prominence.</li>
 <li>Infraserratus bursa: Located deep to the <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> angle of the scapula, reducing friction between the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> and the chest wall</li>
 <li>Supraserratus bursa: Located and reducing friction between the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> and <a href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">subscapularis</a> at the <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> angle of the scapula.</li>
 <li>Infraserratus bursa: Located between the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> and the chest wall at the <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> angle of the scapula.</li>
</ul>
<h4>Bursae associated with the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">glenohumeral joint</a> and the acromioclavicular joint:</h4>
<ul>
 <li>Subacromial Bursa: Located <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> to the <a href="https://brookbushinstitute.com/courses/supraspinatus" target="_blank" rel="noopener">supraspinatus</a> tendon and <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> to the acromion process (in the subacromial space). Functions to reduce friction during elevation of the arm as the <a href="https://brookbushinstitute.com/courses/supraspinatus" target="_blank" rel="noopener">supraspinatus</a> contracts and the tendon <a id="glide" data-tip="1599" target="_blank" href="/glossary-term/glide" class="glossary">slides</a> beneath the coracoacromial arch.</li>
 <li>Subcoracoid Bursa: Located <a class="mw-redirect" title="Anterior (anatomy)" href="https://en.wikipedia.org/wiki/Anterior_%28anatomy%29" target="_blank" rel="noopener">anterior</a> to the <a title="Subscapularis muscle" href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">subscapularis</a>, <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> to the tendon of the short head of the biceps brachii, and <a class="mw-redirect" title="Inferior (anatomy)" href="https://en.wikipedia.org/wiki/Inferior_%28anatomy%29" target="_blank" rel="noopener">inferior</a> to the <a title="Coracoid process" href="https://en.wikipedia.org/wiki/Coracoid_process" target="_blank" rel="noopener">coracoid process</a>. Functions to reduce friction between the <a class="mw-redirect" title="Coracobrachialis" href="https://brookbushinstitute.com/courses/coracobrachialis" target="_blank" rel="noopener">coracobrachialis</a>, <a class="mw-redirect" title="Subscapularis" href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">subscapularis</a>, and short head of the <a title="Biceps" href="https://en.wikipedia.org/wiki/Biceps" target="_blank" rel="noopener">biceps</a> <a title="Tendon" href="https://en.wikipedia.org/wiki/Tendon" target="_blank" rel="noopener">tendons</a>, during shoulder motion.</li>
 <li>Supra-acromial Bursa: Located <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> to the acromion process this bursa generally does not communicate with the sub-acromial bursa (20). The likely function is to serve as a barrier between the bony <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> surface of the acromion and the skin when compressed by external loads (for example, a backpack or purse).</li>
</ul>
<a href="https://www.datocms-assets.com/25800/1642706465-scapulothoracic-bursa-2-2.jpeg" target="_blank" rel="noopener"><img src="https://www.datocms-assets.com/25800/1642706465-scapulothoracic-bursa-2-2.jpeg" title="The location of the scapulothoracic bursa, subscapularis muscles, and supraserratus bursa" alt="The scapulothoracic bursa and subscapularis and supraserratus bursa"></a>
Scapulothoracic or infraserratus bursa &amp; subscapularis or supraserratus bursa

SC, AC, & ST Bursae

<h4>Sensory Innervation</h4>
<ul>
 <li>Sternoclavicular Joint: From the cervical plexus via C3-4 <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots via <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> supraclavicular <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> and <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> to the subclavius.</li>
 <li>Acromioclavicular Joint: From the brachial plexus via C5-6 <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots via suprascapular, pectoral, and axillary nerves.</li>
</ul>
<table class="aligncenter">
 <tbody>
 <tr>
 <td width="322">
 <h3 style="text-align: left;">Muscles Crossing the Joint</h3>
 </td>
 <td style="text-align: left;" width="315">
 <h3>Neural Innervation (1-4,20)</h3>
 </td>
 <td style="text-align: left;" width="170">
 <h3>Nerve Root (1-4, 20)</h3>
 </td>
 </tr>
 <tr>
 <td style="background-color: #c7c7c7;" colspan="3" width="322">Sternoclavicular Joint</td>
 </tr>
 <tr>
 <td width="322">Sternocleidomastoid</td>
 <td width="315">Spinal Accessory Nerve</td>
 <td width="170">Cranial nerve XI</td>
 </tr>
 <tr>
 <td width="322">Subclavius</td>
 <td width="315">Subclavian Nerve</td>
 <td width="170">C5-6</td>
 </tr>
 <tr>
 <td width="322"><a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener"> Pectoralis Major</a></td>
 <td width="315">Medial &amp; Lateral Pectoral Nerves</td>
 <td width="170">C5-T1</td>
 </tr>
 <tr>
 <td style="background-color: #c7c7c7;" colspan="3" width="322">Acromioclavicular Joint</td>
 </tr>
 <tr>
 <td width="322">Upper <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">Trapezius</a></td>
 <td width="315">Spinal Accessory Nerve</td>
 <td width="170">Cranial nerve XI</td>
 </tr>
 <tr>
 <td width="322">Deltoid</td>
 <td width="315">Axillary Nerve</td>
 <td width="170">C5-6</td>
 </tr>
 <tr>
 <td style="background-color: #c7c7c7;" colspan="3" width="322">Scapulothoracic Joint</td>
 </tr>
 <tr>
 <td>Middle and Lower <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">Trapezius</a></td>
 <td>Spinal Accessory Nerve</td>
 <td>Cranial nerve XI</td>
 </tr>
 <tr>
 <td width="322"><a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids Major &amp; Minor</a></td>
 <td width="315">Dorsal Scapular Nerve</td>
 <td width="170">C5</td>
 </tr>
 <tr>
 <td width="322"><a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">Levator Scapulae</a></td>
 <td width="315">Dorsal Scapular Nerve</td>
 <td width="170">C5</td>
 </tr>
 <tr>
 <td width="322"><a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus Anterior</a></td>
 <td width="315">Long Thoracic Nerve</td>
 <td width="170">C5-7</td>
 </tr>
 <tr>
 <td width="322"><a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">Latissimus Dorsi</a></td>
 <td width="315">Thoracodorsal Nerve</td>
 <td width="170">C6-8</td>
 </tr>
 <tr>
 <td width="322"><a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">Pectoralis Minor</a></td>
 <td width="315">Medial Pectoral Nerve (sometimes with Lateral Pectoral Nerve)</td>
 <td width="170">C8-T1 (sometimes with C5-7)</td>
 </tr>
 </tbody>
</table>
<a href="https://www.datocms-assets.com/25800/1642706560-brachial-plexus.png"><img src="https://www.datocms-assets.com/25800/1642706560-brachial-plexus.png" title="The branches of the brachial plexus running to the upper body extremities" alt="Nerves of the brachial plexus"></a>
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See &quot;Book&quot; section below) Bartleby.com: Gray&apos;s Anatomy, Plate 807, Public Domain, https://commons.wikimedia.org/w/index.php?curid=541662

SC, AC, & ST Nerves

<h3>Osteokinematics</h3>
Before discussing movement at the sternoclavicular (SC) and acromioclavicular (AC) joints, it is important to acknowledge the intimate relationship between these joints and the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">glenohumeral (GH) joint</a>. This group of joints has been referred to as the &quot;shoulder joint complex&quot; (3, pg 232). Each joint can be thought of as a link in a chain, as motion of one joint does not generally occur without motion of the others. Motion of the &quot;shoulder joint complex&quot; is usually simplified to include movement of the scapula (scapulothoracic joint) and humerus, excluding consideration of the SC and AC joints independently, and referred to as scapulohumeral rhythm. Scapulohumeral rhythm is easiest to describe during flexion and/or abduction of the shoulder (often referred to as upper extremity &quot;elevation&quot; in research); as the shoulder complex moves into elevation, there is approximately 1&#xB0; of scapular motion for every 2&#xB0; of <a href="https://brookbushinstitute.com/article/shoulder-glenohumeral-joint" target="_blank" rel="noopener noreferrer">GH</a> motion (23).
Motion of the scapula, referred to as scapulothoracic joint motion (ST) is dependent on the coordinated motion of the SC and AC joints. These two joints provide the bony connections between the scapula and the thorax. SC and AC joint motion may be additive where both joints contribute to the same net direction of ST motion. SC and AC joint motions may also work in opposition to each other, where larger motions of the SC joint are opposed by the AC joint to maintain congruence between the scapula and the ribcage.
SC, AC, and ST joint motion are not typically measured independently, but in conjunction with the full range of motion of the &quot;shoulder joint complex&quot; (24). Individual SC and AC joint motion can be more challenging to observe and quantify (25). Even ST joint motion, which is easily observed visually, is tough to measure reliably. This results in a tendency for more variability in the ranges of motion reported for the SC, AC, and ST joints in the body of research and texts.
<h4>See Kinesiology of the shoulder and scapula for a list of prime movers, synergists, antagonists, neutralizers, stabilizers and fixators for all joint actions.</h4>

<a href="https://www.datocms-assets.com/25800/1642706642-levangiejoint_ch7_f018.png"><img src="https://www.datocms-assets.com/25800/1642706642-levangiejoint_ch7_f018.png" title="An image of scapular depression and accompanying SC and AC joint arthrokinematics " alt="Arthrokinematics of the sternoclavicular and acromioclavicular joint during scapular depression"></a>
Scapular depression and accompanying SC and AC joint <a id="arthrokinematics" data-tip="1859" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">Arthrokinematics</a> - Cynthia C. Norkin, Pamela K. Levangie, Joint Structure and Function: A Comprehensive Analysis: Fifth Edition &#xA9; 2011 F.A. Davis Company

SC, AC, & ST Joint Actions

<h4>Sternoclavicular (SC) Joint Kinematics: Clavicle on Sternum&#xA0;</h4>
The SC joint is the most <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> link and the only bony attachment of the upper extremity to the <a id="axial-skeleton" data-tip="1290" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial skeleton</a>. Motion of this joint is responsible for positioning the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> clavicle and AC joint in space, to aid in the <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> alignment of the glenoid fossa with the humeral head during <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">glenohumeral (GH</a>) motion (1, pg 130). There are three degrees of freedom at the SC joint, therefore there are six available motions, each described below. It is worth noting that the function of this joint in positioning the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> clavicle results in larger ranges of motion than those seen at the AC joint.
The range of motion values provided should only be used as a guideline, as these joints are not typically measured. As mentioned above, functional measurement of SC and AC joint motion usually occurs in conjunction with measurement of <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">GH</a> motion. For example, the scapula is allowed to follow motion of the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">GH</a> joint during <a id="goniometry" data-tip="1523" target="_blank" href="/glossary-term/goniometry" class="glossary">goniometry</a>, with full range signifying the first resistance barrier that includes scapular motion but excludes trunk motion (26). While this method allows the practitioner to <a id="assessment" data-tip="1486" target="_blank" href="/glossary-term/assessment" class="glossary">assess</a> the range of motion of the SC, AC &amp; ST joints in the context of <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">GH</a> motion, it does not lend itself to measurement of the individual links. The values provided below were measured primarily by researchers using digital motion analysis systems.
<ul>
 <li>Elevation of the clavicle
 <ul>
 <li>Elevators: Sternocleidomastoid and <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">upper trapezius</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">Pectoralis major</a>, subclavius and costoclavicular ligament</li>
 <li>Optimal Range of Motion (ROM): up to 48&#xB0; (1, 3)
 <ul>
 <li>Different researchers report values ranging from 9&#xB0; - 30&#xB0; (24)</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Depression of the clavicle
 <ul>
 <li>Depressors: <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">Pectoralis major</a> and subclavius</li>
 <li>Limited by: Sternocleidomastoid, <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">upper trapezius</a>, <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> &amp; <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> capsular ligaments (<a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> portions), and interclavicular ligament</li>
 <li>Optimal ROM: 10&#xB0;-15&#xB0; (1, 3)</li>
 </ul>
 </li>
 <li>Protraction of the clavicle
 <ul>
 <li>Protractors: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, p<a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">ectoralis minor</a> indirectly via &quot;passive motion of the clavicle.&quot; The muscles that contribute to clavicle prostration do no attach to the clavicle. It is through motion of the scapula being imparted on the clavicle via the AC joint that motion occurs</li>
 <li>Limited by: Costoclavicular ligament (<a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> portion), <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> capsular ligament and by retractors of the scapula (<a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a>, <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">middle trapezius</a>, l<a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">evator scapula</a>)</li>
 <li>Optimal ROM: 15&#xB0;-30&#xB0; (1, 3)</li>
 </ul>
 </li>
 <li>Retraction of the clavicle
 <ul>
 <li>Retractors: <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids</a>, <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">middle trapezius</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapula</a> indirectly via &quot;passive motion of the clavicle.&quot; The muscles that contribute to clavicle prostration do no attach to the clavicle. It is through motion of the scapula being imparted on the clavicle via the AC joint that motion occurs</li>
 <li>Limited by: Costoclavicular ligament (<a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> portion), <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> capsular ligament, and muscles that perform scapula protraction (<a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">pectoralis minor</a>)</li>
 <li>Optimal ROM: 15&#xB0;-30&#xB0; (1, 3, 24, 25)</li>
 </ul>
 </li>
 <li>Posterior Rotation (<a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> surface of the clavicle to face <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a>)
 <ul>
 <li>Posterior Rotators: Clavicular fibers of <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">upper trapezius</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">Pectoralis major</a>, subclavius, pectoral fascia, and clavipectoral fascia</li>
 <li>Optimal ROM: 20&#xB0;-50&#xB0; (1, 3, 24)</li>
 </ul>
 </li>
 <li>Anterior Rotation (clavicle return to neutral from <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> rotation)
 <ul>
 <li>Anterior Rotators: <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">Pectoralis major</a></li>
 <li>Limited by: Sternocleidomastoid, platysma, investing layer of deep cervical fascia</li>
 <li>Optimal ROM: &lt;10&#xB0; (return to resting position from <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> rotation) (3)</li>
 </ul>
 </li>
</ul>

Sternoclavicular (SC) Joint Kinematics

<h4>Acromioclavicular (AC) Joint Kinematics: Scapula on clavicle</h4>
Motion at the AC joint is the more <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> link of the joints connecting the upper extremity to the trunk. This joint serves primarily to fine-tune ST motion to maintain <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> congruence between the scapula and thorax (1, pg 130). There are three degrees of freedom at this joint and six available motions. Range of motion values provided should be thought of as guidelines only, and are not typically measured clinically (measurement of shoulder complex described in the SC joint section above).
<ul>
 <li>Upward Rotation (upward and outward motion of the <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> angle of the scapula - upward tilting of the glenoid fossa)
 <ul>
 <li>Upward Rotators: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">upper and lower trapezius</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a> and coracoclavicular ligament</li>
 <li>Optimal ROM: 30&#xB0; (1, 3)
 <ul>
 <li>Other researchers have observed ranges from 32&#xB0; - 64&#xB0; (24)</li>
 <li>Occurs actively in conjunction with shoulder flexion or abduction; cannot occur as an isolated movement.</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Downward Rotation
 <ul>
 <li>Downward Rotators: <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a>, and <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">upper and lower trapezius</a></li>
 <li>Optimal ROM: 17&#xB0; (3)
 <ul>
 <li>Occurs actively in conjunction with shoulder extension or adduction (return to neutral); cannot occur as an isolated movement.</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Internal Rotation (glenoid fossa faces anteromedially - often follows ST protraction)
 <ul>
 <li>Internal Rotators: <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">Pectoralis minor</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">middle trapezius</a>, and <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a></li>
 <li>Optimal ROM: 20&#xB0;-35&#xB0; depending on accompanying upper extremity movement (3)
 <ul>
 <li>has also been measured at 3&#xB0; -8&#xB0; (24)</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>External Rotation (glenoid fossa faces posterolaterally - often follows ST retraction)
 <ul>
 <li>External Rotators: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">middle trapezius</a>, and <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">Pectoralis minor</a></li>
 <li>Optimal ROM: 20&#xB0; - 35&#xB0; depending on accompanying upper extremity movement (3, 24)</li>
 </ul>
 </li>
 <li>Anterior Tipping
 <ul>
 <li>Anterior Tippers: <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">Upper trapezius</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a> and <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a> and <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">lower trapezius</a></li>
 <li>Optimal ROM: 20&#xB0; - 40&#xB0; depending on accompanying upper extremity movement (3)</li>
 </ul>
 </li>
 <li>Posterior Tilting
 <ul>
 <li>Posterior Tilters: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a> and <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">lower trapezius</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">Upper trapezius</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a>, and <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a></li>
 <li>Optimal ROM: 20&#xB0; - 40&#xB0; depending on accompanying upper extremity movement (3)
 <ul>
 <li>Has also been observed to range between 9&#xB0; - 40&#xB0; depending on accompanying upper extremity motion (24)</li>
 </ul>
 </li>
 </ul>
 </li>
</ul>

Acromioclavicular (AC) Joint Kinematics

<h4>Scapulothoracic (ST) Joint Kinematics (Motion of the Scapula)</h4>
The joint actions below describe the observed motion of the scapula on the thorax as a result of combined SC and AC joint motion. These are the conventional joint actions used to describe motion of the shoulder girdle:
<ul>
 <li>Elevation
 <ul>
 <li>Elevators: <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">Upper trapezius</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a>, and <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">Lower trapezius</a>, <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a> and <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a></li>
 <li>Optimal Range of Motion (ROM): not available and not typically measured clinically
 <ul>
 <li>Contributing motions from the SC joint: clavicular elevation</li>
 <li>Contributing motions from the AC joint: slight downward rotation (to maintain the scapula vertical), slight anterior/posterior tilting, and internal/external rotation as needed to maintain scapula against the thorax</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Depression
 <ul>
 <li>Depressors: <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">Lower trapezius</a>, <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi,</a> <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">Upper trapezius</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a>, and <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a></li>
 <li>Optimal ROM: not available and not typically measured clinically
 <ul>
 <li>Contributing motions from the SC joint: clavicular depression</li>
 <li>Contributing motions from the AC joint: slight upward rotation (to maintain the scapula vertical), slight anterior/posterior tilting, and internal/external rotation as needed to maintain scapula against the thorax</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Upward Rotation
 <ul>
 <li>Upward Rotators: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">upper and lower trapezius</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a><a href="https://brookbushinstitute.com/article/pectoralis-minor" target="_blank" rel="noopener">, </a><a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a>, coracoclavicular ligament</li>
 <li>Optimal ROM: up to 50-60&#xB0; (1, 3, 24)
 <ul>
 <li>Contributing motions from the SC joint: clavicular elevation and <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> rotation
 <ul>
 <li>Ludewig et al. noted significant clavicular retraction when the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">glenohumeral (GH</a>) joint was performing abduction (25).</li>
 </ul>
 </li>
 <li>Contributing motions from the AC joint: scapula upward rotation, <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> tipping, and internal/external rotation as needed to maintain scapula against the thorax</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Downward Rotation
 <ul>
 <li>Downward Rotators: <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a><a href="https://brookbushinstitute.com/article/pectoralis-minor" target="_blank" rel="noopener">, </a><a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, upper and lower <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">trapezius</a></li>
 <li>Optimal ROM: return to resting position from upward rotation
 <ul>
 <li>Contributing motions from the SC joint: clavicular depression and <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> rotation</li>
 <li>Contributing motions from the AC joint: scapula downward rotation, <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> tipping, and internal/external rotation as needed to maintain scapula against the thorax</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Protraction
 <ul>
 <li>Protractors: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a></li>
 <li>Limited by: Middle <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">trapezius</a>,<a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener"> rhomboids</a>, <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">lower trapezius</a> and <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a></li>
 <li>Optimal ROM:
 <ul>
 <li>Contributing motions from the SC joint: clavicular protraction</li>
 <li>Contributing motions from the AC joint: scapula internal rotation</li>
 </ul>
 </li>
 </ul>
 </li>
 <li>Retraction (<a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> border of scapula moves toward the spine, glenoid fossa faces more <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a>)
 <ul>
 <li>Retractors: Middle <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">trapezius</a>, <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a>, <a href="https://brookbushinstitute.com/courses/trapezius-activation" target="_blank" rel="noopener">lower trapezius</a>, <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a></li>
 <li>Limited by: <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a></li>
 <li>Optimal ROM:
 <ul>
 <li>Contributing motions from the SC joint: clavicular retraction</li>
 <li>Contributing motions from the AC joint: scapula external rotation</li>
 </ul>
 </li>
 </ul>
 </li>
</ul>

Scapulothoracic (ST) Joint Kinematics

Motion of the AC, SC, and ST joints is influenced by muscles, fascia, and nerves that cross multiple joints. Further, the motion of <a class="glossaryLink " title="Glossary: Proximal" href="https://brookbushinstitute.com/glossary/proximal/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Proximal&lt;/div&gt;&lt;div class=glossaryItemBody&gt;An anatomical direction; closer to the trunk or center of the body&lt;br /&gt;&lt;br /&gt;The hip joint is at the &lt;em&gt;proximal&lt;/em&gt; end of the femur.&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">proximal</a> joints may influence the position of bones, force vectors, moment arms, and the dissipation of force.
<h4>Joints:</h4>
<ul>
 <li>Thoracic spine: In a study by Ottowa et al. thoracic kyphosis was correlated with shoulder impingement syndrome (SIS) (41). It is likely that scapular <a id="dyskinesis" data-tip="1693" target="_blank" href="/glossary-term/dyskinesis" class="glossary">dyskinesis</a> is correlated, or may be the bridge between thoracic kyphosis and shoulder joint dysfunction.</li>
 <li>Cervical spine: Studies have shown that forward head <a class="glossaryLink " title="Glossary: Posture" href="https://brookbushinstitute.com/glossary/posture/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Posture&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Arthro- and osteo-kinematic alignment maintained by myofascial activity and length, as a result of sensation, integration and activation by the nervous system - both statically and dynamically.&lt;br /&gt;&lt;br /&gt;Example, &quot;good form&quot; is an example of ideal &lt;em&gt;posture&lt;/em&gt; for a given exercise.&lt;br /&gt;&lt;br /&gt;&#xA9; 2017 Brent Brookbush&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">posture</a> alters <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> recruitment in overhead tasks, including a reduction in the activity of the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> in those with chronic cervical pain (28-30).</li>
 <li>Glenohumeral joint: The relationship between the glenohumeral and scapulothoracic joint is well documented, going back to a study by Inman et al. in 1944 (23). Several studies have correlated shoulder impingement/pain with scapular <a class="glossaryLink " title="Glossary: Dyskinesis" href="https://brookbushinstitute.com/glossary/dyskinesis/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Dyskinesis&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Faulty or abnormal movement; an&lt;span class=&quot;_Tgc&quot;&gt; alteration of normal kinematics.&lt;/span&gt;&lt;br /&gt;&lt;br /&gt;For example, joint stiffness or a reduction in arthrokinematics motion that results in limited osteokinematic range of motion - inadequate inferior glide of the femoral head resulting in limited abduction of the hip.&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">dyskinesis</a>, noting a reduction in <a class="glossaryLink " title="Glossary: Posterior" href="https://brookbushinstitute.com/glossary/posterior/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Posterior&lt;/div&gt;&lt;div class=glossaryItemBody&gt;An anatomical direction; toward the back&lt;br /&gt;&lt;br /&gt;Example, the gluteus maximus is on the &lt;em&gt;posterior&lt;/em&gt; side of the pelvis and hip.&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">posterior</a> tipping and upward rotation and an increase in scapular internal rotation (27, 35 - 41).</li>
 <li>Radioulnar joint: Two studies have demonstrated that dysfunction of the elbow and forearm may alter scapular <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity and endurance (42, 43).</li>
</ul>
<h4>Muscles:</h4>
<ul>
 <li>All muscles crossing the shoulder and scapula (as described throughout the article)</li>
 <li>Of special consideration:
 <ul>
 <li><a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">Latissimus Dorsi</a>: Links the glenohumeral joint, scapula, lumbar spine, sacroiliac joint, and pelvis</li>
 <li><a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">Pectoralis Major</a>: Links the shoulder to the sternoclavicular and sternocostal joints</li>
 <li><a href="https://brookbushinstitute.com/courses/deltoids" target="_blank" rel="noopener">Deltoids</a>: Links the glenohumeral and AC joints</li>
 <li><a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">Levator Scapulae</a> and <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">Upper trapezius</a>: Link the scapula and cervical spine</li>
 <li>Sternocleidomastoids: Links the cervical spine and the SC joints</li>
 <li><a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">Middle and Lower Trapezius</a> and <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">Rhomboids</a>: Link the scapula and thoracic spine</li>
 <li><a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">Lower Trapezius</a>: may link the scapula and the lumbar spine via the thoracolumbar fascia</li>
 </ul>
 </li>
</ul>
<h4>Fascial Structures:</h4>
<ul>
 <li>Thoracolumbar fascia (TLF): The TLF, as the central structure of the <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">Posterior Oblique Subsystem (POS)</a>, may transmit force and sensory information to the investing fibers of the <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">lower trapezius</a> (56). This would add to the influence the TLF has on the scapula by transmitting force between the <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a> and gluteus medius and the <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a> (38, 56).</li>
 <li>The torso fascia: The fascia of the torso runs nearly continuously from clavicle to pelvis, and wraps around the torso to invest in the subscapularis and axillary fascias. Starting with the pectoral fascia, the pectoral fascia is a thin lamina covering the surface of the <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">pectoralis major</a>&#xA0;and sending numerous extensions between fascicles. This fascia originates from the sternum and clavicle (underneath the platysma (2)) and courses in multiple directions, running continuous with the fascia of the shoulder and biceps, axilla, and abdomen (56). Undercover the <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> at the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> border of the <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">pectoralis major</a>; the lamina splits to envelop the <a class="mw-redirect" title="Pectoralis minor" href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor </a>and runs continuous with the clavipectoral fascia. The axillary fascia (a blending of the pectoral and clavipectoral fascial sheaths) splits at the <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a>, one layer coursing superficial all the way to the spinous processes of the thoracic spine, the other ducking under the <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a> to envelop the <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a>, and potentially doubling back on itself to encase the <a href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">subscapularis</a>. At the lower part of the thoracic region, the deep pectoral fascia is well-developed and is continuous with the fibrous sheaths of the <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener">rectus abdominis</a> and <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a>. Although few would argue that the <a href="https://brookbushinstitute.com/courses/pectoralis-major">pectoralis major</a> and <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">minor</a> muscles have synergistic functions, when we examine all of the muscles mentioned in the description of the &quot;torso fascia&quot; we can start to see a pushing/throwing/spiral synergy of <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> that builds on the <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">Anterior Oblique Subsystem (AOS)</a>.
 <ul>
 <li><a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">Pectoralis major</a></li>
 <li><a class="mw-redirect" title="Pectoralis minor" href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">Pectoralis minor</a></li>
 <li><a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">Latissimus dorsi</a></li>
 <li><a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">Serratus anterior</a></li>
 <li><a href="https://brookbushinstitute.com/courses/subscapularis" target="_blank" rel="noopener">Subscapularis</a></li>
 <li><a href="https://brookbushinstitute.com/courses/muscular-anatomy" target="_blank" rel="noopener">Rectus abdominis</a></li>
 <li><a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">External obliques</a></li>
 </ul>
 </li>
</ul>
<h4>Neural Structures:</h4>
<ul>
 <li>The motor and sensory nerves of the arm and shoulder joint originate from the c4 &#x2013; c7 <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots and <a class="glossaryLink " title="Glossary: Posture" href="https://brookbushinstitute.com/glossary/posture/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Posture&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Arthro- and osteo-kinematic alignment maintained by myofascial activity and length, as a result of sensation, integration and activation by the nervous system - both statically and dynamically.&lt;br /&gt;&lt;br /&gt;Example, &quot;good form&quot; is an example of ideal &lt;em&gt;posture&lt;/em&gt; for a given exercise.&lt;br /&gt;&lt;br /&gt;&#xA9; 2017 Brent Brookbush&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">form</a> the brachial plexus, before diverging into individual nerves. The suprascapular, thoracodorsal, long thoracic, <a class="glossaryLink " title="Glossary: Lateral" href="https://brookbushinstitute.com/glossary/lateral/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Lateral&lt;/div&gt;&lt;div class=glossaryItemBody&gt;An anatomical direction; further from the midline&lt;br /&gt;&lt;br /&gt;Example, the anterior deltoid is &lt;em&gt;lateral&lt;/em&gt; to the pectoralis major&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">lateral</a> and <a class="glossaryLink " title="Glossary: Medial" href="https://brookbushinstitute.com/glossary/medial/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Medial&lt;/div&gt;&lt;div class=glossaryItemBody&gt;An anatomical direction; closer to the midline&lt;br /&gt;&lt;br /&gt;Example, the pectoralis major is &lt;em&gt;medial&lt;/em&gt; to the anterior deltoid&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">medial</a> pectoral nerves do not cross the shoulder. Dysfunction involving these nerves may be <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> to SC, AC, and ST joint <a id="dyskinesis" data-tip="1693" target="_blank" href="/glossary-term/dyskinesis" class="glossary">dyskinesis</a> (this is not implying that these joints are the only joints that may contribute, but that they may be the primary reason). The axillary, musculocutaneous, upper, and lower subscapular nerves all cross the shoulder after passing underneath the clavicle and <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a>. The median, ulnar and radial nerves continue to cross the elbow and wrist. Upper extremity neural dysfunction may be a sign of dysfunction of the cervical spine, sternoclavicular joint, acromioclavicular joint, scapular <a id="dyskinesis" data-tip="1693" target="_blank" href="/glossary-term/dyskinesis" class="glossary">dyskinesis</a>, as well as <a class="glossaryLink " title="Glossary: Movement Impairment" href="https://brookbushinstitute.com/glossary/movement-impairment/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Movement Impairment&lt;/div&gt;&lt;div class=glossaryItemBody&gt;The absence of ideal posture as a result of maladaptation by one or multiple tissues within the human movement system.&lt;br /&gt;&lt;ul&gt;&lt;br /&gt; &lt;li&gt;&lt;i&gt;&#x201C;Postural Dysfunction&#x201D; and &#x201C;Movement Impairment&#x201D; are synonyms.&lt;/i&gt;&lt;/li&gt;&lt;br /&gt;&lt;/ul&gt;&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">movement impairment</a> of the shoulder, elbow, and wrist.</li>
</ul>
<div id="attachment_85482" class="wp-caption aligncenter"><img src="https://www.datocms-assets.com/25800/1642708971-forward-head-posture-fix-discount.jpeg" title="An image comparing forward head posture and neutral posture" alt="Neutral head posture compared to forward head posture "></div>

Postural Dysfunction and the Sternoclavicular, Acromioclavicular & Scapulothoracic Joints

<ul>
 <li>In <a title="UBD" href="https://brookbushinstitute.com/courses/upper-body-dysfunction-ubd" target="_blank" rel="noopener">Upper Body Dysfunction (UBD)</a> the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">shoulder</a> is often the joint of primary concern (for patient and practitioner alike); however, it is important to note that the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">shoulder</a> does not function independently. Several studies have shown a strong correlation between shoulder dysfunction and scapular <a class="glossaryLink " title="Glossary: Dyskinesis" href="https://brookbushinstitute.com/glossary/dyskinesis/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Dyskinesis&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Faulty or abnormal movement; an&lt;span class=&quot;_Tgc&quot;&gt; alteration of normal kinematics.&lt;/span&gt;&lt;br /&gt;&lt;br /&gt;For example, joint stiffness or a reduction in arthrokinematics motion that results in limited osteokinematic range of motion - inadequate inferior glide of the femoral head resulting in limited abduction of the hip.&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">dyskinesis</a> (39-41), shoulder/scapular <a class="glossaryLink " title="Glossary: Dyskinesis" href="https://brookbushinstitute.com/glossary/dyskinesis/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Dyskinesis&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Faulty or abnormal movement; an&lt;span class=&quot;_Tgc&quot;&gt; alteration of normal kinematics.&lt;/span&gt;&lt;br /&gt;&lt;br /&gt;For example, joint stiffness or a reduction in arthrokinematics motion that results in limited osteokinematic range of motion - inadequate inferior glide of the femoral head resulting in limited abduction of the hip.&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">dyskinesis</a> and cervical dysfunction (28-30), and a study by Otoshi et al. showed a link between shoulder impingement and thoracic kyphosis (34). In essence, the shoulder functions as part of an <a class="glossaryLink " title="Glossary: Integration" href="https://brookbushinstitute.com/glossary/integration/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Integration&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Making a whole of parts.&lt;br /&gt;&lt;br /&gt;Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.&lt;/div&gt;" style="background: transparent; color: #34363a; text-decoration: underline; box-sizing: border-box; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; font-family: inherit; line-height: 1.4; margin: 0px; padding: 0px; vertical-align: baseline;">integrated</a> system of joints that include the <a href="https://brookbushinstitute.com/courses/shoulder-glenohumeral-joint" target="_blank" rel="noopener">shoulder</a>, scapula, cervical and thoracic spine, and likely the joints of the ribs (costovertebral and sternocostal).</li>
 <li>Relative to the sternoclavicular (SC), acromioclavicular (AC), and scapulothoracic (ST) joints, the alterations in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity in those exhibiting <a title="Upper Body Dysfunction (UBD)" href="https://brookbushinstitute.com/courses/upper-body-dysfunction-ubd" target="_blank" rel="noopener">UBD</a> are perfectly explained by alterations in <a id="osteokinematic-motion" data-tip="1518" target="_blank" href="/glossary-term/osteokinematic-motion" class="glossary">osteokinematic motion</a>. However, this statement can only be made if the <a id="osteokinematic-motion" data-tip="1518" target="_blank" href="/glossary-term/osteokinematic-motion" class="glossary">osteokinematic motion</a> analyzed is <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> tipping and/or downward rotation, as mentioned in the Lawrence et al. study (40), and not the often cited protraction and elevation that stem from older descriptions of scapular <a id="dyskinesis" data-tip="1693" target="_blank" href="/glossary-term/dyskinesis" class="glossary">dyskinesis</a>. This includes over-activity of the <a href="https://brookbushinstitute.com/courses/levator-scapulae" target="_blank" rel="noopener">levator scapulae</a>, <a href="https://brookbushinstitute.com/courses/rhomboids" target="_blank" rel="noopener">rhomboids</a>, <a href="https://brookbushinstitute.com/courses/pectoralis-minor" target="_blank" rel="noopener">pectoralis minor</a>, subclavius, and <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">upper trapezius</a>, and under-activity of the <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">middle and lower trapezius</a> and <a href="https://brookbushinstitute.com/courses/serratus-anterior" target="_blank" rel="noopener">serratus anterior</a> (35-38, 63). The inhibition noted in the <a href="https://brookbushinstitute.com/courses/deltoids" target="_blank" rel="noopener">anterior and middle deltoid</a> (63) is similar to the inhibition noted in the <a href="https://brookbushinstitute.com/courses/pectoralis-major" target="_blank" rel="noopener">pectoralis major</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> of pitchers with shoulder pain (51, 52), and may be the result of &#x201C;prime mover inhibition&#x201D; in an attempt of the shoulder to protect itself from further damage. Again, these muscles are only mentioned here due to their potential to stabilize the AC joint. A <a id="model" data-tip="1469" target="_blank" href="/glossary-term/model" class="glossary">model</a> of <a id="arthrokinematics" data-tip="1863" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic</a> <a id="dyskinesis" data-tip="1693" target="_blank" href="/glossary-term/dyskinesis" class="glossary">dyskinesis</a> is described above; however, as it is a <a id="hypothesis" data-tip="1446" target="_blank" href="/glossary-term/hypothesis" class="glossary">hypothesis</a> based on indirect evidence, more definitive and direct research is needed.</li>
 <li>In <a title="LPHCD" href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">Lumbo Pelvic Hip Complex Dysfunction (LPHCD)</a> and <a title="Sacroiliac Joint Motion and Predictive Model of Dysfunction" href="https://brookbushinstitute.com/courses/sacroiliac-joint-motion-and-predictive-model-of-dysfunction" target="_blank" rel="noopener">Sacroiliac Joint Dysfunction (SIJD)</a> the scapula does not play a role; however, the <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a> provides a bridge for the perpetuation of dysfunction from the pelvis to the scapula and the shoulder and visa-versa (31). The most common presentation of this link is <a title="LPHCD" href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">LPHCD</a> or <a title="Sacroiliac Joint Motion and Predictive Model of Dysfunction" href="https://brookbushinstitute.com/courses/sacroiliac-joint-motion-and-predictive-model-of-dysfunction" target="_blank" rel="noopener">SIJD</a> resulting in <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a> over-activity and a loss of arm elevation and scapula upward rotation. Although scapular <a id="dyskinesis" data-tip="1693" target="_blank" href="/glossary-term/dyskinesis" class="glossary">dyskinesis</a> may theoretically result in <a title="LPHCD" href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">LPHCD</a> or <a title="Sacroiliac Joint Motion and Predictive Model of Dysfunction" href="https://brookbushinstitute.com/courses/sacroiliac-joint-motion-and-predictive-model-of-dysfunction" target="_blank" rel="noopener">SIJD</a> via the <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener">latissimus dorsi</a>, clinically, this would appear to be far less common. It has been the experience of the Brookbush Institute (BI) that in those exhibiting <a title="LPHCD" href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">LPHCD</a> or <a title="Sacroiliac Joint Motion and Predictive Model of Dysfunction" href="https://brookbushinstitute.com/courses/sacroiliac-joint-motion-and-predictive-model-of-dysfunction" target="_blank" rel="noopener">SIJD</a> and a loss of arm elevation and scapular upward rotation, scapular motion will return without <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> intervention, once <a title="LPHCD" href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">LPHCD</a> or <a title="Sacroiliac Joint Motion and Predictive Model of Dysfunction" href="https://brookbushinstitute.com/courses/sacroiliac-joint-motion-and-predictive-model-of-dysfunction" target="_blank" rel="noopener">SIJD</a> is resolved. An additional relationship exists between the thoracolumbar fascia (TLF) and the investing fibers of the <a href="https://brookbushinstitute.com/courses/trapezius-muscle" target="_blank" rel="noopener">lower trapezius</a> (56); however, it has been the experience of the BI that this relationship is not clinically <a id="relevance" data-tip="1505" target="_blank" href="/glossary-term/relevance" class="glossary">relevant</a>.</li>
 <li>In <a title="LLD" href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener">Lower Leg Dysfunction (LLD)</a>, the shoulder plays no significant role.</li>
</ul>

Shoulder Dysfunction Relative to Postural Dysfunction

Videos

Overhead Squat Assessment: Upper Body Dysfunction

Serratus Anterior Manual Muscle Testing for an Active Population

Serratus Anterior Isolated Activation

Lower Trapezius Manual Muscle Testing

Lower Trapezius Activation

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 </li>
 <li>Ludewig P.M., Cook, T.M. (2000) Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Physical Therapy. 80 (3) 276-291</li>
 <li>Lawrence, R. L., Braman, J. P., Laprade, R. F., &amp; Ludewig, P. M. (2014). Comparison of 3-dimensional shoulder complex kinematics in individuals with and without shoulder pain, part 1: sternoclavicular, acromioclavicular, and scapulothoracic joints. journal of orthopaedic &amp; sports physical therapy, 44(9), 636-A8</li>
 <li>Fayad F, Roby-Brami A, Yazbeck C, Hanneton S, Lefevre-Colau MM, Gautheron V, Poiraudeau S, Revel M. (2008). &ldquo;Three-dimensional scapular kinematics and scapulohumeral rhythm in patients with glenohumeral osteoarthritis or frozen shoulder.&rdquo; 2008 Jbiomech, 41(2): 326-332</li>
 <li>Ayhan, C., Camci, E., &amp; Baltaci, G. (2015). Distal radius fractures result in alterations in scapular kinematics: A three-dimensional motion analysis. Clinical Biomechanics.</li>
 <li>Day, J. M., Bush, H., Nitz, A. J., &amp; Uhl, T. L. (2015). Scapular Muscle Performance in Individuals With Lateral Epicondylalgia. Journal of Orthopaedic &amp; Sports Physical Therapy, (Early Access), 1-35
 <ul>
 <li>Exercise</li>
 </ul>
 </li>
 <li>Suprak DN, Bohannon J, Morales G, et al. (2013). Scapular kinematics and shoulder elevation in a traditional push-up. Journal of Athletic Training. 48(6): 826-835</li>
 <li>Ha, S., Kwon, O., Cynn, H., Lee, W., Kim, S., Park, K. (2013). Selective activation of the infraspinatus muscle. Journal of Athletic Training. 48(3). 346-352</li>
 <li>Dark A, Ginn KA, Halaki M. (2007). Shoulder muscle recruitment patterns during commonly used rotator cuff exercises: an electromyographic study. Pys Ther. 87: 1039-1046</li>
 <li>Kaya, E., Zinnuroglu, M., Tugeu, I. (2010) Kinesio taping compared to physical therapy modalities for the treatment of shoulder impingement syndrome. Clinical Rheumatology. (30) 201-207</li>
 <li>Wang, C., McClure, P., Pratt, N., Nobilini, R. Stretching and Strengthening Exercises: Their Effect on Three-Dimensional Scapular Kinematics. Arch Phys Med Rehabil. 1999 vol. 80, 923-929</li>
 <li>Cools, A.M., Dewitte, V., Lanszweert, F., Notebaert, D., Roets, A., Soetens, B., Cagnie, B., Witvrouw, E.E. (2007) Rehabilitation of Scapular Muscle Balance. Which Exercises to Prescribe? Am J Sports Med, 35(10), 1744-1751</li>
 <li>Uhl, T. L., Carver, T. J., Mattacola, C. G., Mair, S. D., &amp; Nitz, A. J. (2003). Shoulder musculature activation during upper extremity weight-bearing exercise. Journal of Orthopaedic &amp; Sports Physical Therapy, 33(3), 109-117</li>
 <li>Reed D, Cathers I, Halaki M, Ginn KA. (2015). Does load influence shoulder muscle recruitment patterns during scapular plane abduction? Journal of Science and Medicine in Sport.</li>
 <li>Hardwick DH, Beebe JA, McDonnell MK, Lang CE. (2006). A comparison of serratus anterior muscle activation during a wall slide exercise and other traditional exercises. Journal of Orthopaedic &amp; Sports Physical Therapy. 36(12) 903-910
 <ul>
 <li>Pectoralis Inhibition</li>
 </ul>
 </li>
 <li>Wang HK, Cochorane T. 2001. Mobility impairment, muscle imbalance, muscle weakness, scapular asymmetry and shoulder injury in elite volleyball athletes. J Sport Med Phys Fitness 41(3): 403-10</li>
 <li>Glousman R, Jobe F, Tibone J, Moynes D, Antonelli D, Perry J. Dynamic Electromyographic analysis of the throwing shoulder with glenohumeral instability. J Bone <span class="glossaryLink " data-tooltip="Where two or more bones meet.&lt;br /&gt;Etymology: joint (n.) late 13c., &ldquo;a part of a body where two bones meet and move in contact with one another,&rdquo; from Old French joint &ldquo;joint of the body&rdquo; (12c.), from Latin iunctus &ldquo;united, connected, associated,&rdquo; past participle ofiungere &ldquo;join&rdquo; (see &lt;a href=&quot;http://www.etymonline.com/index.php?term=jugular&amp;allowed_in_frame=0&quot;&gt;jugular&lt;/a&gt;). (&lt;a href=&quot;http://www.etymonline.com/index.php?term=joint&quot;&gt;Etymology Online&lt;/a&gt;)">Joint Surg 70A(2):220-226, 1988.</li>
 <li>Glousman R, Jobe F, Tibone J, Moynes D, Antonelli D, Perry J. Dynamic Electromyographic analysis of the throwing shoulder with glenohumeral instability. J Bone Joint Surg 70A(2):220-226, 1988
 <ul>
 <li>Fascia</li>
 </ul>
 </li>
 <li>Schleip R; Findley T; Chaitow L., Huijing P. Fascia: The Tensional Network of the Human Body &copy; 2012 Elsevier Ltd.
 <ul>
 <li>Texts on Postural Dysfunction</li>
 </ul>
 </li>
 <li>Florence Peterson Kendall, Elizabeth Kendall McCreary, Patricia Geise Provance, Mary McIntyre Rodgers, William Anthony Romani, Muscles: Testing and Function with <span class="glossaryLink" data-tooltip="Posture refers to the optimal alignment of bones and joints both statically and dynamically. &ldquo;Good form&rdquo; could be defined as optimal posture during exercise."><a class="glossaryLink" title="Glossary: Posture" href="https://brookbushinstitute.com/glossary/posture/" target="_blank" rel="noopener noreferrer" data-tooltip="Posture refers to the optimal alignment of bones and joints both statically and dynamically. &ldquo;Good form&rdquo; could be defined as optimal posture during exercise.">Posture</a> and Pain: Fifth Edition &copy; 2005 Lippincott Williams &amp; Wilkins</li>
 <li>Phillip Page, Clare Frank, Robert Lardner, Assessment and Treatment of Muscle Imbalance: The Janda Approach &copy; 2010 Benchmark Physical Therapy, Inc., Clare C. Frank, and Robert Lardner</li>
 <li>Dr. Mike Clark &amp; Scott Lucette, &ldquo;NASM Essentials of Corrective Exercise Training&rdquo; &copy; 2011 Lippincott Williams &amp; Wilkins</li>
 <li>Leon Chaitow, Muscle Energy Techniques: Third Edition, &copy; Pearson Professional Limited 2007</li>
 <li>Shirley A Sahrmann, Diagnoses and Treatment of Movement Impairment Syndromes, &copy; 2002 Mosby Inc.</li>
 <li>Karel Lewit. Manipulative Therapy: Musuloskeletal Medicine &copy; 2007 Elsevier
 <ul>
 <li>Additional Research</li>
 </ul>
 </li>
 <li>Scovazzo, M.L., Browne, A., Pink, M., Jobe, F.W., and Kerrigan, J. (1991). The painful shoulder during freestyle swimming: An electromyographic cinematographic analysis of twelve muscles. The American Journal of Sports Medicine. 19(6). 577-582</li>
 <li>Peolsson, A. L., Peolsson, M. N., &amp; Jull, G. A. (2013). Cervical muscle activity during loaded arm lifts in patients 10 years postsurgery for cervical disc disease. Journal of manipulative and physiological therapeutics, 36(5), 292-299</li>
 <li>Falla, D., Jull, G., &amp; Hodges, P. W. (2004). Feedforward activity of the cervical flexor muscles during voluntary arm movements is delayed in chronic neck pain. Experimental brain research, 157(1), 43-48. (Delayed onset of DCF with arm movement)</li>
 <li>Jull, G., Kristjansson, E., &amp; Dall&rsquo;Alba, P. (2004). Impairment in the cervical flexors: a comparison of whiplash and insidious onset neck pain patients. Manual therapy, 9(2), 89-94</li>
 <li>
 <div id="gs_cit1" class="gs_citr" tabindex="0">Falla, D., O&rsquo;Leary, S., Farina, D., &amp; Jull, G. (2011). Association between intensity of pain and impairment in onset and activation of the deep cervical flexors in patients with persistent neck pain. The Clinical journal of pain, 27(4), 309-314.</div>
 </li>
</ol>

Bibliography

<html><head></head><body>© 2017 Brent Brookbush
Questions, comments and criticisms welcome and encouraged -</body></html>

Copyright

A-Band - Refers to the part of the muscle cell that looks darker under a microscope.  This area of the cell is darker due to parallel arrangement of thicker filaments (myosin) and overlap with the thinner filaments (actin).
<ul>
 	<li>As a muscle contracts, the A-band is where actin and myosin interact.</li>
</ul>
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

Accuracy - the proportion of individuals correctly identified by the test results.
<ul>
 	<li>For example, a special test with perfect accuracy would imply a test has 100% specificity, 100% sensitivity, 100% positive predictive value and 100% negative predictive values.</li>
</ul>

Action Potential - A rapid change in voltage, resulting in a wave of excitation, that may result in stimulation of a nerve or muscle cell.
<ul>
 	<li>In order for an action potential to be initiated, the resting membrane voltage must exceed the excitation threshold, which then results in a cascade of depolarization and the "wave of excitation." Any stimulus below that threshold will not result in an action potential, and a stimulus greater than the threshold will not increase a single action potential, but may result in additional action potentials.  In this way, the action potential functions more like an on/off switch (all or none), and less like a dimmer switch.</li>
</ul>

A single-joint movement pattern (most often) designed to load a specific under-active muscle(s), while minimizing the contribution of over-active synergists via specific cues/joint motions.
<ul>
 	<li style="text-align: left;">Activation techniques/exercises are performed with the intent of addressing a muscle exhibiting a reduction in activity (tone) as a result of, or contributing to postural dysfunction.</li>
 	<li style="text-align: left;">Activation techniques/exercises cannot be multi-joint movement patterns due to relative flexibility, altered reciprocal inhibition, and synergistic dominance resulting in compensation patterns.</li>
</ul>
Example, <a href="https://brentbrookbush.com/articles/corrective-exercise-articles/activation/gluteus-medius-activation-progression/" target="_blank">gluteus medius activation</a> involves resisted hip abduction while minimizing the contribution of the TFL via hip extension.

Active stretching is a term used to describe a stretch that involves an active contraction of opposing musculature to lengthen a muscle to its end range. Generally these stretches are held for 2-5 seconds and repeated for 8-15 repetitions.

Adenosine triphosphatase (ATPase): is the enzyme responsible for catalyzing (initiating and accelerating) the decomposition of ATP to ADP.
<ul>
 	<li>This dephosphorylation (breakdown) reaction releases energy for processes like muscular contraction.</li>
</ul>

Adenosine triphosphate (ATP): The molecule that functions as a universal energy-transfer molecule, providing most of the energy associated with muscular contraction and human movement. ATP is composed of an adenine group, a ribose group, and three molecules of inorganic phosphates.
<ul>
 	<li>Energy is provided when hydrolysis results in the cleaving of a phophate group; resulting in adenosine diphosphate, an inorganigic phosphate group, and energy.</li>
</ul>

Algometry - measuring the amount of pressure to result in sensitivity or pain, using an algometer.
<ul>
 	<li>Generally, research uses algometry to establish a minimum pain pressure threshold (PPT), in which a lower PPT implies more sensitivity and pain, and a higher PPT implies less sensitivity and pain. PPT is a common outcome measure in trigger point research.</li>
</ul>
<a href="https://brentbrookbush.com/wp-content/uploads/2019/07/Algometer.jpg"><img class="aligncenter wp-image-140177" src="https://brentbrookbush.com/wp-content/uploads/2019/07/Algometer.jpg" alt="Image of an Algometer" width="500" height="333" /></a>

All-or-none principle - a nerve or muscle cell's response to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential (threshold of an action potential), the nerve or muscle fiber will respond completely; otherwise, there is no response.

Example, when a motor unit in the biceps brachii is stimulated it contracts the same way whether a 10 lb or 50 lb dumbbell is lifted.  It is actually the number of muscle cells and the size of the motor unit that determines force output.

&nbsp;

The transition period between eccentric load and concentric contraction during a repetition of an exercise.  This term is most often used in reference to power/plyometric exercises, in which a shorter amortization phase is believed to be beneficial.  The shorter amortization phase may better use the stored energy from the elastic deformation of connective tissue and enhance synchronization of myotatic (stretch) reflex with maximum voluntary contraction.

Example, the athlete was cued to spend as little time as possible in the bottom of their squat stance (the amortization phase) during a set of box jumps.

Muscles that oppose the prime mover and synergists for a given joint action.

That is, all the muscles that can perform the opposing joint action.

Example: The triceps and anconeus are antagonists during elbow flexion.

An anatomical direction; toward the front

Example, the face is on the anterior aspect of the head

Appendicular Skeleton - referring to the bones the bones of the arms and legs, as well as the bones that support them. This includes the pelvis, clavicle and scapula. There are approximately 126 bones in the appendicular skeleton.
<ul>
 	<li>Etymology - Appendicular, as in appendage, "that which is appended to something as a proper part," 1640s, from <a class="crossreference" href="https://www.etymonline.com/word/append?ref=etymonline_crossreference">append</a> + <a class="crossreference" href="https://www.etymonline.com/word/-age?ref=etymonline_crossreference">-age</a>. - <a href="https://www.etymonline.com/word/appendage" target="_blank" rel="noopener">Etymology Online</a></li>
</ul>
"Appendicular skeleton" is a label referring to a set of bones whose function is distinct from the bones of the "<a href="https://brentbrookbush.com/glossary/axial-skeleton/" target="_blank" rel="noopener">axial skeleton</a>".

A reflexive decrease in muscle activity due to joint dyskinesis.
For example, a reduction in deep cervical flexor activity as a result of cervical spine dyskinesis.

Arthrokinematic Motion - Small amplitude motions between bone surfaces at a joint.  The arthrokinematic motions are roll, glide (slide or translation), spin, compression and distraction (traction). Arthrokinematic motions accompany osteokinematic motions to maintain joint congruence.
<ul>
 	<li>Example, arthrokinematic motion of the talus includes posterior glide on the tibia during ankle dorsiflexion.</li>
</ul>
Synonyms include: arthrokinematics, passive accessory motion, joint play and component motion

&nbsp;

Assessment - is the act of assessing, i.e. determining the importance, size, or value of -

In most cases, the results of an assessment are compared to normative data. If the individual exhibits values that are within normal parameters, it may be assumed that the aspect of health or motion assessed is not contributing to the patient's complaint, symptoms or movement impairment. If the results fall outside of normal parameters, it may indicate that the aspect of health or motion assessed is contributing to, or being affected by the patient/client's complaint, symptoms, or movement impairment. In some cases, the results of an assessment are compared to an "ideal model." In this case, deviations from the ideal are noted as potential issues. For example, deviations noted in the <a title="Introduction to the Overhead Squat Assessment" href="https://brentbrookbush.com/online-courses/articles/assessment/introduction-overhead-squat-assessment/" target="_blank">Overhead Squat Assessment</a> are compared to an "ideal model" of posture and motion.

Assessments used by human movement professionals can be divided into three broad categories:
<ul>
 	<li>"Clear" the Patient/Client for Intervention - These are tests, assessments and evaluations used to determine if a patient/client's issue may improve given the assessing professional's scope, skills, abilities and willingness to treat that individual.
<ul>
 	<li>For example, many of the special tests used in orthopedic medicine assist in determining the level of pathology or likelihood of a particular diagnosis. Certain issues and diagnoses are beyond the scope of the human movement professional, and are better treated by diagnostic professionals in the medical community (physicians, podiatrists, surgeons, etc.). A Calf Squeeze (Thompson) Test is one example, in which a positive sign may indicate a rupture of the Achilles tendon that may be better treated via surgical intervention.</li>
</ul>
</li>
 	<li>Highlight Contraindications - Tests, assessments and evaluations used to stratify risk or preclude a professional from addressing certain tissues, motions or using a particular technique.
<ul>
 	<li>For example, the Vertebral Artery Test (VBI) is often used to determine if high velocity thrust mobilizations (manipulations) are safe for a patient with cervical dysfunction.</li>
</ul>
</li>
 	<li>Refine Exercise/Intervention Selection: Tests, assessments and evaluations used to assist the professional in determining which techniques, modalities and exercises will best address a patient/client's complaints or desired goals.
<ul>
 	<li>Most movement assessments fall into this category. For example, a positive <a href="https://brentbrookbush.com/vimeo_videos/elys-test-rectus-femoris-flexibility-assessment/" target="_blank">Ely's Test</a> may indicate a need to release and/or lengthen the <a href="https://brentbrookbush.com/articles/anatomy-articles/muscular-anatomy/rectus-femoris/" target="_blank">rectus femoris</a>.</li>
</ul>
</li>
</ul>
Note: An assessment, or assessment result, may fall into more than one category. For example, although goniometry is an assessment most often used to Refine Exercise/Intervention Selection, if a range of motion is significantly altered, with an abnormal end-feel, and/or causes the patient or client/pain, the individual may need to be referred to a physician for further testing and Clearance to resume rehab activities.  Further, that same patient may return to the human movement professional with a list of Contraindicated Activities from the physician. - "When in doubt, refer out!"

Axial Skeleton - referring to the bones of the head, neck, trunk and spinal column (does not include pelvis). There are approximately 80 bones in the axial skeleton.
<ul>
 	<li>Etymology - Axial, as in "axis", referring to "imaginary motionless straight line around which a body (such as the Earth) rotates," from Latin axis "axle, pivot, axis of the earth or sky" - <a href="https://www.etymonline.com/word/axis" target="_blank" rel="noopener">Etymology Online</a></li>
</ul>
"Axial skeleton" is a label referring to a set of bones whose function is distinct from the bones of the "<a href="https://brentbrookbush.com/glossary/appendicular-skeleton/" target="_blank" rel="noopener">appendicular skeleton</a>".

Balance - The ability to maintain a body’s center of mass over its base of support. Balance can be static or dynamic.
<ul>
 	<li>For example, maintaining balance is harder on one leg because the center of mass must stay over a much smaller base of support.</li>
</ul>

A ball and socket joint (also called a spheroid joint or spheroidal joint) is a synovial joint in which the rounded or spherical end of one bone fits into a cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of axes, which have one common center. Examples include the hip and shoulder (glenohumeral joint)

Base of support (BoS) - refers to the area beneath an object or person, and the area within the perimeter created by every point of contact that the object or person makes with the supporting surface. This may include the <a href="https://brentbrookbush.com/articles/anatomy-articles/muscular-anatomy/gluteus-maximus/" target="_blank" rel="noopener">glutes</a> of someone sitting on a chair, or the back of someone leaning against a wall.
<ul>
 	<li>For example, during a single leg balance the BoS is the area of the foot in contact with the surface; however, when a person is standing on two feet, the BoS is the area of both feet and the surface between them.</li>
</ul>

Pertaining to both sides

Example, bilateral rows are performed with both arms at the same time.

Case-control Study - a particular form of retrospective study that samples a matched group of people who have, and do not have the outcome being studied. A case-control study is a quasi-experimental design, often used in medicine to aid in determining potential contributing factors (cannot determine causality). In this study type exposure is the dependent variable and outcome is independent.
<ul>
 	<li>Example, in this retrospective case-control, medical records were investigated for trends correlated with cervical pain (1).
<ol>
 	<li>Mäkela, M., Heliövaara, M., Sievers, K., Impivaara, O., Knekt, P., &amp; Aromaa, A. (1991). Prevalence, determinants, and consequences of chronic neck pain in Finland. American journal of epidemiology, 134(11), 1356-1367.</li>
</ol>
</li>
</ul>

An anatomical direction; toward the tail, relative to humans this term is often used to refer to "in the direction of the tale (toward the feet)".

Example, to release the trapezius muscle the therapist used a force directed caudally.

Center of mass (CoM) - an object's mean position of mass; that is, a point that is perfectly surrounded by an equal amount mass in all directions.

Center of gravity (CoG) - point where gravity appears to act. Since the human body is so small compared to the earth, we can assume gravity acts uniformly on the body, and that CoG and CoM are the same.
<ul>
 	<li>Example, the CoM of the human body while lying down or standing straight up is close to our navel. However, it is possible that during a resistance exercise, the combination of the body's weight and the weight of the resistance will place the combined CoM outside the body. For example, during the mid-portion of a <a href="https://brentbrookbush.com/vimeo_videos/back-squat/" target="_blank" rel="noopener">back squat</a> the CoM would be several anterior to the naval.</li>
</ul>

An anatomical direction; toward the head (synonym: cranial)

Example, hip pain was felt with any force directed cephalad.

Cohort Study - a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic), performing a cross-section at intervals through-out a period of time. A cohort study is a quasi-experimental design often used in medicine to aid in determining etiology or a cause-and-effect relationship. In this study type exposure is the independent variable and outcome is dependent.
<ul>
 	<li>Example, the study by Cholewicki et al. (1) investigated Yale Varsity Athletes (the cohort) with 2 and 3 year follow up (longitudinal design) and found that trunk muscle response time to off-loading was predictive of future low back injury.</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/core/increased-trunk-muscle-latency-may-cause-rather-than-result-from-low-back-pain/" target="_blank" rel="noopener noreferrer">Cholewicki, J., Silfies, S., Shah, R., Greene, H., Reeves, N. Alvi, K., Goldberg, B. (2005). Delayed trunk muscle reflex responses increase the risk of low back injuries. Spine. 30(23), 2614-2620</a></li>
</ol>

Comparable Sign: A combination of pain, stiffness and/or spasm during examination that is comparable to the patients symptoms.
<ul>
 	<li>One common error made during evaluation with special tests is attention given to any discomfort or pain, rather than attempting to identify the pain/discomfort related to the patient's complaint (concordant/comparable sign). Many special tests purposefully test tissue limits and are at least mildly uncomfortable in every individual. Basing your assessment on positive tests that resulted in "concordant/comparable signs" will improve your chances of arriving at the correct diagnosis.</li>
</ul>

An alternative movement pattern that has been adopted to compensate for dysfunction/impairment in the human movement system.
Example: A lack of calf extensibility may limit dorsiflexion, leading to the knees bowing inward (functional valgus) and excessive forward lean of the torso during a squat.

An arthrokinematic motion - the approximation of joint surfaces; that is, a force that directs one bone surface into another resulting in a reduction in intra-articular volume. Although widely thought of as a "destructive force", it is likely best to consider compression as a naturally occurring, stabilizing force. Any arthrokinematic force in excess (spin, glide, roll, traction) may be viewed as potentially deleterious.

For example, during a squat the femoral head is compressed into the acetabulum by muscular forces, bodyweight and any additional external load.

Concave (Concavity) - Having an outline or surface curved like the interior surface of a bowl or sphere - to cave-in or curve inward.
<ul>
 	<li>Example, the internal surfaces of the pelvis is concave, holding some of the bodies viscera.</li>
</ul>

Concordant Sign - The patient's specific pain, symptom or complaint. 
<ul>
 	<li>One common error made during evaluation with special tests is attention given to any discomfort or pain, rather than attempting to identify the pain/discomfort related to the patient's complaint (concordant/comparable sign). Many special tests purposefully test tissue limits and are at least mildly uncomfortable in every individual. Basing your assessment on positive tests that resulted in "concordant/comparable signs" will improve your chances of arriving at the correct diagnosis.</li>
</ul>

Conductivity: Stimulation results in more than a local effect (1).
<ul>
 	<li>For example, in a muscle cell the stimulation of a motor endplate results in a change in cell membrane polarity that rapidly propagates (is conducted) along the entire length of the muscle cell, stimulating all sacromere.</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

A condyloid joint (also called condylar, bicondylar, ellipsoid, or ellipsoidal) is an ovoid articular surface, or condyle, that is received into an elliptical cavity.  These joints permit movement in two planes.  Examples include the knee, metacarpophalangeal joints and metatarsophalangeal joints.

Connective Tissue Cell - One of the four basic types of animal tissue, consisting mostly fibers and ground substance.  These cells are specialized to binds organs together, holds them in place, protect them from external forces, and may fill space in the body's cavities.

Example, the body's muscles are enclosed in durable connective tissue sheets known as the "epimysium", "perimysium", and "endomysium," which and in support and transmitting force.
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

Contractility: The ability to shorten (1).
<ul>
 	<li>Contractility: Muscle cells are unique in the amount they can shorten when stimulated; this is this largerly due to the highly organized and unique arrangement of myofilaments (actin and myosin).</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

Pertaining to the opposite side

Example, the external oblique muscle performs contralateral rotation; rotation to the opposite side.

Convex (Convexity) - Having an outline or surface curved like the exterior of a circle or sphere - to bulge or curve outward.
<ul>
 	<li>Example, the top of your head is shaped by the convex exterior surface of your skull.</li>
</ul>

Correlational Research - Non-experimental <a href="https://www.questionpro.com/blog/what-is-research/">research</a> method in which the statistical relationship between two variables is investigated.
<ul>
 	<li>In this research by Kwon et al., a correlation was noted between a decrease in extensibility during a hamstring length test (goniometry) and current knee pain (1).</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/knee/correlation-patellofemoral-pain-syndrome-pfps-hamstring-activity/" target="_blank" rel="noopener">Kwon O, Yun M, and Lee W. (2014). Correlation between intrinsic patellofemoral pain syndrome in young adults and lower extremity biomechanics. J. Phys. Ther. Sci. 26: 961-964</a></li>
</ol>

Counter-nutation - posterior rotation of sacrum relative to ilium, and/or anterior rotation of ilium relative to sacrum.
<ul>
 	<li>The pelvic floor muscles are examples of muscle that may counter-nutate the sacrum.</li>
</ul>
[caption id="attachment_126335" align="aligncenter" width="400"]<a href="https://brentbrookbush.com/wp-content/uploads/2018/10/Nutation.png"><img class=" wp-image-126335" src="https://brentbrookbush.com/wp-content/uploads/2018/10/Nutation.png" alt="Nutation and Counter-nutation of the Sacroiliac Joint" width="400" height="967" /></a> Nutation and Counter-nutation of the Sacroiliac Joint[/caption]

&nbsp;

Crossover (Study) Design - A type of longitudinal, repeated measures quasi-experimental design in which each group receives both treatments, but at different times. It is named "crossover" due to the patients "crossing-over" to the other treatment or sham group after a specified period of time.
<ul>
 	<li>This type of study has the advantage of every individual serving as their own control, which may reduce the influence of confounding variables.</li>
 	<li>Unfortunately, the design itself introduces the chances that anyone receiving the experimental variable in the first period will continue to be effected in the second period.</li>
</ul>
In a study by Senna et al., a cross-over design was used to investigate the difference load made on inter-set rest intervals (1).
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/strength-training-research-corner/heavy-vs-light-load-single-joint-exercise-performance-with-different-rest-periods/" target="_blank" rel="noopener">Senna, G.W., Rodrigues, B.M., Sandy, Scudese, Bianco, A, &amp; Dantas, E.H.M. (2017). Heavy vs light load single-joint exercise performance with different intervals. Journal of Human Kinetics, 58, 197-206. </a></li>
</ol>

Cross-sectional Study - a research design that involves gathering data from a population or representative subset at a specific point in time.
<ul>
 	<li>Example, the study by Karimi-Mobarake et al.(1) investigated the prevalence of genu varum and genu valgum among school children 7-11 years old in Iran.</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/knee/low-prevalence-of-genu-varum-and-valgum-among-elementary-school-children/" target="_blank" rel="noopener noreferrer">Karimi-Mobarake, M., Kashefipour, A., Yousfnejad, Z. The prevalence of genu varum and genu valgum in primary school children in Iran 2003-2004. (2005) Journal of Medical Science 5(1). 52-54</a></li>
</ol>

Cytokine - A broad and loose category of small proteins that act through receptors, and are especially important to immune function (inflammation).
<ul>
 	<li>Cytokines include substances such as interferon, interleukin, and growth factors, which are secreted by certain cells of the immune system and have an effect on other cells. Their definite distinction from hormones is a topic of continued research.</li>
</ul>
&nbsp;

Dependent variable - in research, this is the variable that is changed by the independent variable, most often this is the "outcome" of the study.
<ul>
 	<li>Example, in the study by Cleland et al. (1), the independent variable is "thoracic manipulation," and the dependent variable is "lower trapezius muscle strength."</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/short-term-effects-lower-thoracic-manipulation-lower-trapezius-muscle-strength/" target="_blank" rel="noopener noreferrer">Cleland J, Selleck B, Stowell T, Brown L, Alberini S, St. Cyr H, Caron T. Short-term Effects of Thoracic Manipulation on Lower Trapezius Muscle Strength.  Journal of Manual &amp; Manipulative Therapy. 2004; 12(2): 82-90</a></li>
</ol>

An anatomical direction; further from the trunk or center of the body

Example, the foot is at the distal end of the leg.

An arthrokinematic motion - a force applied to a body part that may result in the separation of joint surfaces, a reduction in intra-articular pressure, and/or an increase in intra-articlar space.

For example, to hang from one's hands (i.g. in preparation for a pull-up) results in a traction force on the glenohumeral joint (shoulder).

An anatomical term of location; back or upper surface

Example, shoe laces may compress tissues on the dorsal surface of the foot

The "drawing-in" maneuver is a common cue used during exercise and rehabilitation programs. A light contraction of the <a href="https://brentbrookbush.com/articles/muscular-anatomy/transverse-abdominis/" target="_blank" rel="noopener">transverse abominis</a> (and potentially the entire <a href="https://brentbrookbush.com/articles/corrective-exercise-articles/core-subsystems/intrinsic-stabilization-subsystem/" target="_blank" rel="noopener">intrinsic stabilization subsystem</a>) achieved by gently pulling the lower abdominal region away from one's waist band. This should have minimal effect on breathing, and should not be confused with a maximal contraction of the <a href="https://brentbrookbush.com/articles/muscular-anatomy/transverse-abdominis/" target="_blank" rel="noopener">transverse abdominis</a> resulting in a "vacuum pose".
<ul>
 	<li>Research often refers to this maneuver as the "abdominal drawing-in maneuver"; abbreviated ADIM.</li>
</ul>
Development and introduction of this cue into practice is based on the pivotal research and resulting text:
<ol>
 	<li>Carolyn Richardson, Paul Hodges, Julie Hides. Therapeutic Exercise for Lumbo Pelvic Stabilization – A Motor Control Approach for the Treatment and Prevention of Low Back Pain: 2nd Edition (c) Elsevier Limited, 2004</li>
</ol>

Faulty or abnormal movement; an alteration of normal kinematics.

For example, joint stiffness or a reduction in arthrokinematics motion that results in limited osteokinematic range of motion - inadequate inferior glide of the femoral head resulting in limited abduction of the hip.

The seeping into, or abnormal collection of fluid in a body cavity.

For example, knee effusion describes swelling within the knee joint.

Note: the word "effusion" is used differently in medicine than it is used in reference to the movement (seeping out) of liquids and gases, for example in chemistry.

&nbsp;

A trait of body tissues that allows a tissue to return to its resting length or state after deformation or stretch.
Example:  Muscle is elastic tissue; many muscles will return to their resting length after being stretched to 150% of that length without any appreciable change in tissue quality.

Elasticity: Elasticity refers to the ability of a cell to return to its resting length after being stretched/lengthened.
<ul>
 	<li>Note: this term is often confused with extensibility. Elasticity is not the ability to stretch; it is the ability to return to normal length after being stretched. Muscle tissue, connective tissue and even nerve tissue have varying levels of elasticity.</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

Epithelial cell - One of the four basic cell types, found lining the body's cavities, blood vessels, organs and constitutes most gland tissue.  These cells are specialized to aid with absorption, secretion, or act as a barrier from foreign objects.
<ol>
 	<li>Saladin, K. S., &amp; Miller, L. (1998). Anatomy &amp; physiology. New York (NY): WCB/McGraw-Hill.</li>
</ol>

Equilibrium - a state in which opposing forces or influences are balanced.
<ul>
 	<li>For example, to maintain a neutral trunk while pushing or pulling a weight in one hand, your core musculature must balance the force by creating an equal amount of force in the opposite direction.</li>
</ul>

The study of causation, or origination. The word is commonly used in the medical professions, where it may refer to the study of why things occur, or the reason behind why things act a certain way.

For example, the etiology of low back pain is a complex subject, with multiple contributing factors and various structures implicated.

<div class="gs_citr" tabindex="0">Evidence-based medicine (practice) is the integration of best research evidence with clinical expertise and patient(client) values (2)."</div>
<ul>
 	<li class="gs_citr" tabindex="0">...the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients (clients).  It involves the integration of at least (a) clinical expertise/expert opinion, (b) external scientific evidence, and (c) client/patient/caregiver perspectives to provide high-quality services reflecting the interests, values, needs, and choices of the individuals we serve (1).</li>
</ul>
&nbsp;
<ol>
 	<li id="gs_cit1" class="gs_citr" tabindex="0">Sackett, D. L., Rosenberg, W. M., Gray, J. M., Haynes, R. B., &amp; Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn't. Bmj, 312(7023), 71-72.</li>
 	<li class="gs_citr" tabindex="0">Sackett D et al. Evidence-Based Medicine: How to Practice and Teach EBM, 2nd edition. Churchill Livingstone, Edinburgh, 2000, p.1</li>
</ol>

Excitability: The ability of a cell to change in membrane conductance as a response to stimulation.

<ul>
 	<li>For example, muscle cells are specialized to react to a change in membrane potential with contraction, where as nerve cells are specialized to propagate a change in membrane potential along there axons and communicate that message to other tissues via neurotransmitters.
</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

Excitation threshold: The level that a depolarization must reach for an action potential to occur.
<ul>
 	<li>The excitation threshold is a contributing factor to the "all-or-none" response of muscle and nerves cells to a stimulus.</li>
</ul>

Exercise Progression - Modification of an exercise with the intent of promoting adaptation by increasing demand. This can be accomplished by increasing reps, load, tempo, range of motion, complexity, and/or challenge to an individual's stability.
<ul>
 	<li>Because load, reps, tempo and complexity are often explicitly noted, the term "exercise progression" is most often used throughout Brookbush Institute (BI) content to refer to an exercise, or series of exercises that make it harder to maintain stability with good form.
<ul>
 	<li>Sample Exercise Progression: <a href="https://brentbrookbush.com/vimeo_videos/kneeling-chop-pattern/" target="_blank" rel="noopener">Kneeling Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/static-standing-chop-pattern/" target="_blank" rel="noopener">Standing Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/single-leg-chop-pattern/" target="_blank" rel="noopener">Single-leg Chop</a></li>
</ul>
</li>
</ul>

Exercise regression - The opposite of progression; that is, modification of an exercise with the intent of reducing demand. This can be accomplished by decreasing reps, load, tempo, range of motion, complexity, and/or challenge to an individual's stability. Generally, regressions are used to modify an exercise to the client's current level of ability, with the intent of improving form, motor learning and retention.
<ul>
 	<li>Because load, reps, tempo and complexity are often explicitly noted, the term "exercise regression" is most often used throughout Brookbush Institute (BI) content to refer to an exercise or series of exercises that make it easier to maintain stability with good form.
<ul>
 	<li>Sample Exercise Regression: <a href="https://brentbrookbush.com/vimeo_videos/single-leg-chop-pattern/" target="_blank" rel="noopener">Single-leg Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/static-standing-chop-pattern/" target="_blank" rel="noopener">Standing Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/kneeling-chop-pattern/" target="_blank" rel="noopener">Kneeling Chop</a></li>
</ul>
</li>
</ul>

Experimental Research - Studies in which the researchers introduce the variable to be studied, with the intent of observing the outcome. This is different than observational research which observes the effect of a variable already present. Many texts also assert that experimental research should include randomization and ideally a control group, as is seen in Randomized Control Trials. Studies in which the variable is introduced by the researchers, but participants are not randomized may be considered Quasi-experimental research.
<ul>
 	<li>In this study by Esformes, the experimental variable was squat depth and the outcome measures observed were various performance measures related to power (1).</li>
</ul>
<ol>
 	<li><a href="https://brookbushinstitute.com/article/back-squat-depth-lower-body-post-activation-potentiation/" target="_blank" rel="noopener">Esformes, J., &amp; Bampouras, T. (2013). Effect of back squat depth on lower-body postactivation potentiation. Journal of Strength and Conditioning Research, 27(11), 2997-3000.</a></li>
</ol>
&nbsp;

Extensibility: The ability of a cell to be stretched or lengthened without damage (1).
<ul>
 	<li>For example, most cells would rupture with even a modest stretch, but muscles can stretch up to 3 times their contracted length.</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

False Negative - the proportion of negatives in a group that were assessed incorrectly (assessed as negative when the patient was actually positive)
<ul>
 	<li>Test Results: Although most tests/assessments result in either a positive or negative, the accuracy of a test is dependent on the number  of positives and negatives that are correct. Therefore, when the accuracy of a test is determined, their are 4 possible results, because a positive or negative result could be right (true) or wrong (false).</li>
</ul>

False Positive - the proportion of positives in a group that were assessed incorrectly (assessed as positive when the patient was actually negative)
<ul>
 	<li>Test Results: Although most tests/assessments result in either a positive or negative, the accuracy of a test is dependent on the number  of positives and negatives that are correct. Therefore, when the accuracy of a test is determined, their are 4 possible results, because a positive or negative result could be right (true) or wrong (false).</li>
</ul>

The function of fascia is to transmit force, provide support, and protect tissues. Fascia can effect motion by:
Transmitting force from one or more muscles (example: the thoracolumbar fascia)
Restricting motion in cases of adaptive shortening and/or adhesion to proximal structures (example: iliotibial band in cases of lower-leg dysfunction)
Elastic recoil after stretching can contribute to force production (example: plyometric exercise)

Note: There is evidence that fascia may house more receptors related to human movement than other tissues. In this way fascia may act as a motherboard for the nervous system

The fascial system does not contract or develop trigger points, and its capacity to adapt to stretching and or strengthening exercise is limited, especially when compared to the adaptive capacity of muscle tissue.

Fibromyalgia - A loosely defined diagnosis that is associated with a combination of widespread pain in combination with 2) tenderness at 11 or more of the 18 specific tender point sites. Consideration may also be given to the presence of psychosocial stressors and inflammatory disease in the patients history. Newer research suggests that fibromyalgia may be at least in part due to central sensitization of myofascial pain, often associated with trigger points (1 - 4).
<ol>
 	<li>Wolfe, F. (2018). Fibromyalgia Syndrome and Fibromyalgia Syndrome Criteria: Problems in Definition and Validity. Fibromyalgia Syndrome and Widespread Pain: From Construction to Relevant Recognition.</li>
 	<li>Wolfe, F., Smythe, H. A., Yunus, M. B., Bennett, R. M., Bombardier, C., Goldenberg, D. L., ... &amp; Fam, A. G. (1990). The American College of Rheumatology 1990 criteria for the classification of fibromyalgia. Arthritis &amp; Rheumatism: Official Journal of the American College of Rheumatology, 33(2), 160-172.</li>
 	<li>Alonso-Blanco, C., Fernandez-de-las-Penas, C., Morales-Cabezas, M., Zarco-Moreno, P., Ge, H. Y., &amp; Florez-García, M. (2011). Multiple active myofascial trigger points reproduce the overall spontaneous pain pattern in women with fibromyalgia and are related to widespread mechanical hypersensitivity. The Clinical journal of pain, 27(5), 405-413.</li>
 	<li>Staud, R., Nagel, S., Robinson, M. E., &amp; Price, D. D. (2009). Enhanced central pain processing of fibromyalgia patients is maintained by muscle afferent input: a randomized, double-blind, placebo-controlled study. PAIN®, 145(1-2), 96-104.</li>
</ol>
&nbsp;

Muscles that act to reduce or prevent movement at proximal joints to improve force transmission.
Example: The muscles of the core are important fixators; reducing motion of the spine/trunk to enhance force transmission between the extremities and environment.

An increase in joint stability via compressive forces resulting from muscular contraction and increased tension in fascial structures (1,2).
<ul>
 	<li>This term is most often used in reference to core intrinsic stabilizers, the thoracolumbar fascia and the sacroiliac joint; however, force closure and form closure have been mentioned in the literature referring to other joints.</li>
 	<li>Related term: Form closure</li>
</ul>
<ol>
 	<li>Andry Vleeming, Vert Mooney, Rob Stoeckart. Movement, Stability &amp; Lumbopelvic Pain: <a class="glossaryLink " title="Glossary: Integration" href="https://brentbrookbush.com/glossary/integration/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Integration&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Making a whole of parts.&lt;br /&gt;&lt;br /&gt;Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.&lt;/div&gt;">Integration</a> of Research and Therapy. (c) 2007 Elsevier Limited</li>
 	<li id="gs_cit1" class="gs_citr" tabindex="0">Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., &amp; Snijders, C. J. (1995). The Posterior Layer of the Thoracolumbar Fascia| Its Function in Load Transfer From Spine to Legs. Spine, 20(7), 753-758.</li>
</ol>

The relative contribution of joint shape and structure to the stability of a joint (1,2).
<ul>
 	<li>This term is most often used in reference to the "rough" articulating surfaces of the sacroiliac joint and the wedge shape of the sacrum; however, force closure and form closure have been mentioned in the literature referring to other joints.</li>
 	<li>Related term: Force closure</li>
</ul>
<ol>
 	<li>Andry Vleeming, Vert Mooney, Rob Stoeckart. Movement, Stability &amp; Lumbopelvic Pain: <a class="glossaryLink " title="Glossary: Integration" href="https://brentbrookbush.com/glossary/integration/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Integration&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Making a whole of parts.&lt;br /&gt;&lt;br /&gt;Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.&lt;/div&gt;">Integration</a> of Research and Therapy. (c) 2007 Elsevier Limited</li>
 	<li id="gs_cit1" class="gs_citr" tabindex="0">Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., &amp; Snijders, C. J. (1995). The Posterior Layer of the Thoracolumbar Fascia| Its Function in Load Transfer From Spine to Legs. Spine, 20(7), 753-758.</li>
</ol>

An arthrokinematic motion - linear motion across a joint surface parallel to the plane of the adjacent joint surface, just as your posterior moves relative to a "slide" in a park.

For example, the glide of facet joint in the spine during spinal flexion and extension, or the posterior glide of the humeral head that must accompany anterior roll to maintain congruence with glenoid fossa during shoulder horizontal adduction.

A plane joint (also called an arthrodial joint, gliding joint or plane articulation) is a synovial joint which allows only gliding movement in the plane of the articular surfaces. The opposed surfaces of the bones are flat or almost flat, with movement generally limited by tight capsules and ligaments. Plane joints are numerous, are most often small, and allow very little motion.  Examples include the carpal joints of the wrist, the tarsal joints of the ankle, and the facet joints of the spine.

"...refers to the measurement of angles, in particular the measurement of angles created at human joints by the bones of the body (1).

&nbsp;
<ol>
 	<li>Cynthia C. Norkin, D. Joyce White. Measurement of Joint Motion: A Guide to Goniometry 3rd Edition. Copyright (C) 2003 by F.A. Davis Company</li>
</ol>

Ground reaction force (GRF) - The force exerted by the ground on the body in contact with it.

For example, when a runner's foot strikes the ground with a force equal to the mass of the individual times their acceleration due to gravity, momentum and muscular exertion, the ground exerts an equal and opposite force on the runner's foot.
<ul>
 	<li>GRF is often measured in research studies using force plates as a means of quantitatively measuring the force generated by an individual.</li>
</ul>

H-Band - Refers to the central zone of a sarcomere that looks lighter under a microscope.  This area of the sarcomere is a lighter portion of the A-band where there is no overlap between the thinner filaments (actin), and the thicker filaments (myosin).
<ul>
 	<li>Example, when a muscle contracts, actin and myosin cross-bridging occurs in the region of the A-band until the H-band is reached where no overlap occurs.</li>
</ul>
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

A hinge joint (also called a ginglymus) is a synovial joint in which the articular surfaces fit one another in a way that only permits motion in one plane. Examples include the elbow, the knee (unless considered a condyloid joint) and the interphalangeal joints.

Holism (holistic) (biological holism) - (from Greek holos "all, whole, entire") is the idea that systems and their properties should be viewed as wholes, not just as a collection of parts.
<ul>
 	<li>Summarized by Aristotle in his "Metaphysics": "The whole is more than the sum of its parts". However, the term "holism" was introduced into language by the South African statesman Jan Smuts as recently as 1926. (Smuts J. C. 1987 [1926]. Holism and evolution. Cape Town: N &amp; S Press.)</li>
</ul>
Example: The Brookbush Institute promotes a holistic approach to human movement science, in which the muscular, fascial, articular and neural systems are not viewed as separable and all proximal segments are considered.

Hormone: Chemical messengers produced by the endocrine system, transported via tissue fluids such as blood, to stimulate cells to "act."
<ul>
 	<li>Example: Growth hormone is secreted by the pituitary gland in the brain; stimulating growth, cell reproduction and cell regeneration in certain types of cells</li>
</ul>
The English physician E. H. Starling discovered in collaboration with the physiologist W. M. Bayliss secretin, the first hormone, in 1902. (1).
<ol>
 	<li>Henriksen, J. H., &amp; de Muckadell, O. S. (2000). Secretin, its discovery, and the introduction of the hormone concept. Scandinavian journal of clinical and laboratory investigation, 60(6), 463-472.</li>
</ol>

A range of motion achieved by the patient/client that is more than normal.
<ul>
 	<li>Note: Both hyper-mobility and hypo-mobility may adversely affect motion and may lead to deleterious effects on joints and soft tissue over time. There is no evidence to suggest that more or less flexibility than normal is beneficial.</li>
</ul>
Example: If an individual can place their forehead on their knees they are likely hypermobile at one, if not several joints

Example 2: 110° of shoulder external rotation would be considered hyper-mobile.

Hyperplasia is an increase in organic tissue size due to an adaptive increase in the number of cells per organ.
<ul>
 	<li>Although muscle hyperplasia has been noted in some animals, human muscle tissue does not seem to have this adaptive ability.</li>
</ul>

A condition of excessive tone of the skeletal muscles; increased resistance of muscle to passive stretching.  May be related to increased neural drive, synergistic dominance, trigger points, reflexive over-activity, and/or muscle length.
Example:  Individuals who exhibit ankle eversion and abduction during an overhead squat assessment likely have hypertonic fibularis (peroneal) muscles.

Muscular hypertrophy is an increase in muscle mass/size due to increase in the volume and cross-sectional area (CSA) of individual muscle cells. The increase in cross-sectional area can be attributed to an an increase in contractile proteins and structural elements (myofibrillar hypertophy), as well as an increase in glycogen storage and elements related to metabolism (sarcoplasmic hypertophy). Hypertrophy is an adaptation of both cardiac and skeletal muscle fibers in response to progressive increases in workload.
<ul>
 	<li>Note: Hypertrophy is not hyperplasia. Hyperplasia is an increase in muscle size due to an adaptive increase in the number of muscle fibers/cells per muscle. This type of adaptation does not occur in human muscle tissue.</li>
</ul>

A range of motion achieved by a patient/client that is less than normal.
<ul>
 	<li>Note: Both hyper-mobility and hypo-mobility may adversely affect motion and may lead to deleterious effects on joints and soft tissue over time. There is no evidence to suggest that more or less flexibility than normal is beneficial.</li>
</ul>
Example: If the end range of shoulder external rotation is reached and measured as 75° during goniometric assessment, the client/patient is exhibiting hypomobility of the glenohumeral joint (shoulder).

Hypothesis - a proposed explanation for a phenomenon; "scientific hypotheses" are generally constructed in a way that is testable or falsifiable.
<ul>
 	<li>Example: The hypothesis, "excessive knee valgus may be correlated with future knee pain and injury," has been the subject of several studies published over the last decade.</li>
</ul>

Diminished tone of skeletal muscles; diminished resistance of muscles to passive stretching.   May be related to inhibition, reciprocal inhibition, arthrokinematics inhibition and/or  increased resting length of muscle.
Example:  If your knees cave (hip adduction) during a squat or leg-press it is likely that your gluteus medius is hypotonic.

I-Band - Refers to the part of the muscle cell that looks lighter under a microscope.  This area of the cell is lighter due to parallel arrangement of thinner filaments (actin), and no overlap with the thicker filaments (myosin).
<ul>
 	<li>As a muscle contracts, the I-bands will decrease in width and move closer to one another.</li>
</ul>
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

Independent variable - in research, this is the variable or phenomenon being manipulated in the study.
<ul>
 	<li>Example, in the study by Ghanbari et al. (1), the independent variable is "knee joint mobilization", the dependent variable is "quadriceps muscle strength."</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/effect-knee-joint-mobilization-quadriceps-muscle-strength/" target="_blank" rel="noopener noreferrer">Ghanbari A. and Kamalgharibi S. (2013). Effect of knee joint mobilization on quadriceps muscle strength. International Journal of Health and Rehabilitation Sciences. 2(4): 186-191</a></li>
</ol>

An anatomical direction; toward the bottom (below)

Example, the mouth is inferior to the eyes

A reduction in neural drive, muscular activity, and or force output due to altered neuromuscular reflex.  Alterations in neuromuscular reflex may occur due to increases in muscle length (hypothesis: increased excitation threshold), altered reciprocal inhibition in response to increased antagonist tone, and or alterations in joint motion (arthrokinematics inhibition).

Making a whole of parts.

Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.

Intermuscular Coordination - Optimal timing and motor unit recruitment of agonists, antagonists, synergists, neutralizers, stabilizers and fixators.

Example: Role of Muscles during Hip Extension
<ul>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Prime Mover" href="https://brentbrookbush.com/glossary/prime-mover/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Prime Mover&lt;/div&gt;The muscle most responsible for a joint action under load -&lt;br /&gt;&lt;br /&gt;That is, the muscle that can produce the most force for a given joint action. Often this term is used synonymously with the term agonist. The prime mover as defined above, may or may not be the most active muscle for a joint action during activities of daily living.&lt;br /&gt;&lt;br /&gt;Example: the gluteus maximus is the most powerful hip extensor and therefore the prime mover; however, the hamstrings are likely the most active hip extensors during low level activities like walking or standing.">Prime Mover</a>:  <a href="https://player.vimeo.com/external/82855344.hd.mp4?s=54c3e7d98fb9d4e0af8d282c85ba9b3e">Gluteus maximus</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Synergists" href="https://brentbrookbush.com/glossary/synergists/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Synergists&lt;/div&gt;Muscles that assist the prime mover in performing a joint action.&lt;br /&gt;&lt;br /&gt;That is, all muscles that can perform a joint action that are not the prime mover, are termed synergists.&lt;br /&gt;Example: The rectus abdominis is the prime mover of spinal flexion. All other muscles that can perform spinal flexion are synergists including – external obliques, internal obliques and psoas.">Synergists</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/biceps-femoris/">Biceps femoris (long head)</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/semitendinosus-and-semimembranosus/">semitendinosus, semimembranosus</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/adductors/">posterior head of adductor magnus</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Antagonist" href="https://brentbrookbush.com/glossary/antagonists/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Antagonist&lt;/div&gt;Muscles that oppose the prime mover and synergists for a given joint action.&lt;br /&gt;&lt;br /&gt;That is, all the muscles that can perform the opposing joint action.&lt;br /&gt;&lt;br /&gt;Example: The triceps and anconeus are antagonists during elbow flexion.">Antagonists</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/psoas/">Psoas</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/iliacus/">iliacus</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/tensor-fascia-latae-tfl/">tensor fascia latae</a> (TFL),<a href="https://brentbrookbush.com/articles/muscular-anatomy/rectus-femoris/"> rectus femoris</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/adductors/">anterior adductors (especially pectineus)</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/sartorius/">sartorius</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Neutralizer" href="https://brentbrookbush.com/glossary/neutralizers/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Neutralizer&lt;/div&gt;Muscles that oppose unwanted joint motions created by the prime mover and/or synergists, and/or muscles that prevent unwanted ancillary motion.&lt;br /&gt;Example: The teres minor and infraspinatus neutralize the internal rotation force created by the pectoralis major during horizontal adduction of the shoulder.">Neutralizers</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/gluteus-minimus/">Gluteus minimus</a> and <a href="https://brentbrookbush.com/articles/muscular-anatomy/gluteus-medius/">anterior fibers of gluteus medius</a> neutralize external rotation force of <a href="https://brentbrookbush.com/articles/muscular-anatomy/gluteus-maximus/">gluteus maximus</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Stabilizer" href="https://brentbrookbush.com/glossary/stabilizers/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Stabilizer&lt;/div&gt;Muscles whose primary role is to improve arthrokinematics by maintaining optimal alignment of joint surfaces.&lt;br /&gt;&lt;br /&gt;Most often these muscles are the most intrinsic muscles of a joint, have a larger percentage of Type I muscle fibers and are rich in proprioceptors.&lt;br /&gt;Example: The muscles of the rotator cuff act as stabilizers for most shoulder motions.">Stabilizers</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/deep-rotators-of-the-hip/">Deep rotators of hip</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Fixator" href="https://brentbrookbush.com/glossary/fixators/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Fixator&lt;/div&gt;Muscles that act to reduce or prevent movement at proximal joints to improve force transmission.&lt;br /&gt;Example: The muscles of the core are important fixators; reducing motion of the spine/trunk to enhance force transmission between the extremities and environment.">Fixators</a>: <a href="https://brentbrookbush.com/articles/core-subsystems/intrinsic-stabilization-subsystem/">Intrinsic stabilization subsystem</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/rectus-abdominis/">rectus abdominis</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/internal-obliques/">internal</a> and <a href="https://brentbrookbush.com/articles/muscular-anatomy/external-obliques/">external obliques</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/quadratus-lumborum/">quadratus lumborum</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/erector-spinae/">erector spinae</a></li>
</ul>
&nbsp;

Example from: <a href="https://brentbrookbush.com/articles/anatomy-articles/introduction-to-functional-anatomy/kinesiology-of-the-hip/" target="_blank" rel="noopener">Introduction to Functional Anatomy: Kinesiology of the Hip</a>

Intramuscular coordination refers to the coordinated recruitment of motor units within a single muscle. This concept is used to explain increases in maximal strength and power; however, the coordinated and sequential recruitment of motor units is also essential to strength endurance and smooth coordinated motion.  Related terminology may include; motor unit recruitment, preferential recruitment, rate coding, sequence, etc..

Example: It is hypothesized that the "shaking" noted during a novice exercisers attempt at an activity like the <a href="https://brentbrookbush.com/vimeo_videos/ball-crunch-and-progressions/" target="_blank">stability ball crunch</a> may be due to relatively poor intramuscular coordination. Rather than smooth, sequential firing of rectus abdominis motor units, groups of motor units turn on and off in an uncoordinated manner.

Pertaining to the same side

Example, the quadratus lumborum performs ipsilateral flexion; lateral flexion toward the same side as the muscle.

An isoform, or variant, is a member of a set of similar proteins, that originate from the same gene, or gene family.
<ul>
 	<li>Example, the variations in myosin heavy chain proteins (MHC I, MHC IIA, MHC IIB/X) that contribute to the characteristic differences between muscle fiber types.</li>
</ul>

“The Prime Assumption”
Everything crossing a joint will influence joint motion during every joint action.

A concept that has expanded over the past several decades to describe the integration of 4 body systems (muscle, joints, fascia and nerves), as well as, the coordinated function of various body segments (e.g. hip, knee and ankle) to produce motion. Kinetic referring to motion, and chain being an analogy for the interdependent link between systems.

Example, the posterior kinetic chain, refers to the integrated function of nerves, muscles, fascia and joints on the posterior side of the body.

The concept of the kinetic chain was originally adapted from the work of a mechanical engineer named Franz Reuleaux (Kinematics of Machinery (1875)) by Dr. Arthur Steindler in 1955 (Steindler A: Kinesiology of the Human Body. Springfield, IL, Charles C. Thomas Co.. 1955).

Latent Trigger Point - A myofascial trigger point that is not painful at rest, only painful when palpated, and may or may not exhibit a characteristic referral pain pattern when palpated.  Latent trigger points do result in an acute point of sensitivity, in a taut band of muscle, and may restrict range of motion (1).

Note: Based on the clinical experience, the Brookbush Institute suggests that latent trigger points (sometimes refereed to as Tender Points) are more common than active trigger points. Further, they are likely addressed more often than trigger points; being the intended target of many soft-tissue mobility techniques.
<ol>
 	<li>David G. Simons, Janet Travell, Lois S. Simons, Travell &amp; Simmons’ Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition,© 1999 Williams and Wilkens</li>
</ol>

An anatomical direction; further from the midline

Example, the anterior deltoid is lateral to the pectoralis major

Length/Tension Relationship - The amount of force generated by a muscle is dependent on sarcomere length.
<ul>
 	<li>The ability of sarcomere to maximally produce force occurs when sarcomere length results in optimal overlap between actin and myosin. Stretching a sarcomere decreases overlap between actin and myosin filaments and reduces force production (1-3). When length is less than optimal, actin from opposite ends overlap and interfere with cross-bridging, and myosin filament are compressed as they contact the the Z-disk also reducing force (4)</li>
</ul>
<ol>
 	<li>Gordon, A. M., Huxley, A. F., &amp; Julian, F. J. (1966). The variation in isometric tension with sarcomere length in vertebrate muscle fibres. The Journal of physiology, 184(1), 170-192.</li>
 	<li>Edman, K. A. P. (1966). The relation between sarcomere length and active tension in isolated semitendinosus fibres of the frog. The Journal of Physiology, 183(2), 407-417.</li>
 	<li>Lieber, R. L., Loren, G. J., &amp; Friden, J. (1994). In vivo measurement of human wrist extensor muscle sarcomere length changes. Journal of neurophysiology, 71(3), 874-881.</li>
 	<li>Lieber, R. L. (2002). Skeletal muscle structure, function, and plasticity. Lippincott Williams &amp; Wilkins.</li>
</ol>
&nbsp;

Levels of Evidence - Relative to evidence-based practice, levels of evidence are an attempt to describe the strength of the results measured in a clinical trial or research study.  Note: levels of evidence do not supersede the critical evaluation of an experienced professional, and should be viewed as guidelines - a meta-analysis may be poorly constructed (Level IA), and a comparative study (Level III) may employ new technologies and a strong methodology.


The Levels of Evidence used by the Brookbush Institute, as described by Shekelle et al.(1):
<ul>
 	<li class="p1">IA - Evidence from meta-analysis of randomized controlled trials</li>
 	<li class="p1">IB - Evidence from at least one randomized controlled trial</li>
 	<li class="p1">IIA - Evidence from at least one controlled study without randomization</li>
 	<li class="p1">IIB - Evidence from at least one other type of quasi-experimental study</li>
 	<li class="p1">III - Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies</li>
 	<li class="p1">IV - Evidence from expert committee reports or opinions or clinical experience of respected authorities, or both</li>
</ul>
<ol>
 	<li>Shekelle, P. G., Woolf, S. H., Eccles, M., &amp; Grimshaw, J. (1999). Developing clinical guidelines. Western Journal of Medicine, 170(6), 348.</li>
</ol>

Likelihood Ratios - Likilihood ratios are used for assessing the value of performing a diagnostic test. They use sensitivity and specificity to determine whether a test result usefully changes the practitioner's chance (probability) of reaching the correct assessment. Calculation of likelihood ratios is based on Baye's theorem.
<ul>
 	<li>Positive Likelihood Ratio (LR+) - The ratio of a positive test result in people with the pathology to a positive test result in people without the pathology.</li>
 	<li>Negative Likelihood Ratio (LR-) - The ratio of a negative test result in people with the pathology to a negative test result in people without the pathology.</li>
</ul>

Longitudinal Study - a research design that involves observing the same variables, several times over a period of time.
<ul>
 	<li>Example, the study by Hewett et al. (1) is a type of longitudinal study called a "cohort study." This study investigated whether excessive knee valgus during landing was a predictor of knee injury risk in adolescent females over the course of a season.</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/knee/research-review-increased-valgus-during-landing-predicts-acl-injury-in-adolescent-female-athletes/" target="_blank" rel="noopener noreferrer">Hewett, T. E., Myer, G. D., Ford, K. R., Heidt, R. S., Colosimo, A. J., McLean, S. G., &amp; Succop, P. (2005). Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes A prospective study. The American journal of sports medicine, 33(4), 492-501</a></li>
</ol>

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Sternoclavicular (SC), Acromioclavicular (AC), and Scapulothoracic (ST) Joint Anatomy

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