Introduction

Techniques and Ending Info

Attachment and Innervations

An Odd Ball

Relative Location

Palpation

Actions

Arthrokinematics

Fascial Integration

Behavior in Postural Dysfunction

Extensor Hallucis Longus (EHL), Extensor Digitorum Longus (EDL), and Fibularis Tertius

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Toe Extensors (Extensor Hallucis Longus, Extensor Digitorum Longus, and Fibularis Tertius)

Extensor Hallucis Longus (EHL) & Extensor Digitorum Longus (EDL) (and Fibularis Tertius (FT))

Exercises and techniques for the toe extensors may contribute to the development of lower body (leg) and total body strength. The toe extensor muscles are located on the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> side of the lower leg, cross the ankle and toe joints, and play a critical role in motion of the foot and ankle. The extensor hallicus longus (EHL), extensor digitorum longus (EDL), and fibularis tertius muscles can also play a role in injury, including hallux rigidus, plantar fasciitis, Achille&apos;s tendonitis, and shin splints. To get the most out of your strength training for lower body muscles, and to aid in the prevention of injuries, you will need more than just foot stretches. Sports medicine professionals should have knowledge of the functional anatomy of the toe extensor muscles, its role in <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a> (behavior in <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> dysfunction and <a id="movement-impairment" data-tip="1575" target="_blank" href="/glossary-term/movement-impairment" class="glossary">movement impairment</a>), role in functional movement, and a repertoire of toe extensor exercises and techniques.
<h4>Brookbush Institute&#x2019;s most recommended techniques for the Toe Extensor Muscles (see videos below):</h4>
<ul>
 <li>Activation: Tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Isolated Activation (With Cueing for EHL and EDL Inhibition)</li>
 <li>Activation: Quad Sets and Progressions</li>
</ul>
<img alt="EHL, EDL, and Fibularis Tertius" title="Dissection of the toe extensor muscles of the foot" src="https://www.datocms-assets.com/25800/1638277038-screen-shot-2016-10-18-at-8-53-53-pm.png">

 Course Description: Toe Extensor

<h4>What&apos;s in a name:</h4>
<ul>
 <li>Extensor - early 18th century: from late Latin, from extens- &apos;stretched out&apos;, from the verb extendere - <a href="http://www.oxforddictionaries.com/us/definition/american_english/extensor?q=extensor" target="_blank" rel="noopener">Oxford Dictionary</a></li>
 <li>Hallucis - mid 19th century: modern Latin alteration of medieval Latin allex, Latin hallus (referring to big toe) - <a href="http://www.oxforddictionaries.com/us/definition/american_english/hallux?q=Hallux" target="_blank" rel="noopener">Oxford Dictionary</a></li>
 <li>Digitorum - From the Latin digitus - referring to a finger or toe - <a href="http://www.oxforddictionaries.com/us/definition/american_english/digit?q=Digit" target="_blank" rel="noopener">Oxford Dictionary</a></li>
 <li>Longus - late 17th century: longus is the Latin word for &apos;long&apos; - <a href="http://www.oxforddictionaries.com/us/definition/american_english/longevous?q=longevous" target="_blank" rel="noopener">Oxford Dictionary</a></li>
</ul>
<img alt="Fibularis Tertius" title="Attachment of the fibularis tertius" src="https://www.datocms-assets.com/25800/1645302158-peroneus_tertius.png" width="164" height="631">
<ul>
 <li style="list-style-type: none;">
 <ul></ul>
 </li>
</ul>

Introduction to the Toe Extensors

<h4>Extensor Hallucis Longus (EHL):</h4>
<ul>
 <li>Origin: Middle two-quarters of the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> surface of the fibula and adjacent interosseous membrane (11, 15).</li>
 <li>Insertion: <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">Base</a> of the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> phalanx of the great toe (11).</li>
 <li>Nerve: Deep fibular (peroneal) <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> arising from the common fibular (peroneal) <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> after splitting from the sciatic <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> arising from the sacral plexus, and originating from <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots L5, S1, and sometimes L4.</li>
</ul>
<h4>Extensor Digitorum Longus (EDL):</h4>
<ul>
 <li>Origin: <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">Lateral</a> condyle of the tibia, <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> 3/4 of the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> surface of the body of the fibula, <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> part of the interosseous membrane, adjacent intermuscular septa (<a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a>), and deep fascia (11, 16).</li>
 <li>Insertion: By four tendons to the second through fifth digits. Each tendon forms an expansion on the <a id="dorsal" data-tip="1554" target="_blank" href="/glossary-term/dorsal" class="glossary">dorsal</a> surface of the toe and divides into an intermediate slip attached to the <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">base</a> of the middle phalanx, and into two <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> slips attached to the <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">base</a> of the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> phalanx (11).</li>
 <li>Nerve: Deep fibular (peroneal) <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> arising from the common fibular (peroneal) <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> after splitting from the sciatic <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> which arises from the sacral plexus, and originates from <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots L5, S1, and sometimes L4 (8, 11, 17).</li>
</ul>
<a href="https://www.datocms-assets.com/25800/1645302313-slide_8.jpeg"><img src="https://www.datocms-assets.com/25800/1645302313-slide_8.jpeg" title="The tendons of the EHL, EDL, fibularis muscles, and tibialis anterior" alt="Extensor muscles of the foot (extensor hallucis longus, tibialis anterior, extensor digitorum longus)"></a> http://slideplayer.com/slide/4337622/

Attachment & Innervations: Extensor Hallucis Longus and Extensor Digitorum Longus

<h4>Fibularis Tertius:</h4>
Although it is titled a &quot;Fibularis&quot; (Peroneal) <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a>, the fibularis tertius has little, if any, similarities to the fibularis muscles. If this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> is present (not everyone has a fibularis tertius), this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> has far more in common with the EHL &amp; EDL. Below is a list of traits:
<ul>
 <li>The fibularis tertius is located in the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> compartment (the fibularis muscles lie in the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> compartment).</li>
 <li>It functions as a dorsiflexor (the fibularis muscles are plantar flexors).</li>
 <li>It is innervated by the deep fibular <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> (the fibularis muscles are innervated by the superficial fibular <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a>).</li>
 <li>Often this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> is actually an outcropping of the EDL (12).
 <ul>
 <li>I know this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> only exists in a relatively small portion of the population (like the palmaris and psoas minor muscles), but maybe we should consider renaming this muscle&#x2026; Extensor Tertius Longus?</li>
 </ul>
 </li>
</ul>
Origin: <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">Distal</a> 1/3 of the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> surface of the fibula, interosseous membrane, and adjacent intermuscular septum (11).
Insertion: <a id="dorsal" data-tip="1554" target="_blank" href="/glossary-term/dorsal" class="glossary">Dorsal</a> surface of the <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">base</a> of the 5th metatarsal (11, 18).
Nerve: Deep fibular (peroneal) <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> arising from the common fibular (peroneal) <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> after splitting from the sciatic <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> arising from the sacral plexus, and originating from <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots L4, L5, S1 (8, 11).
Action: Dorsiflexion of the ankle, as well as, a weak evertor of the foot and ankle (11).
<img alt="Fibularis tertius muscle attaching on the fibula" title="Image of the fibularis tertius muscle of the foot" src="https://www.datocms-assets.com/25800/1645302517-peroneus-tertius-muscle.png" width="259" height="308">

An Odd Ball: Fibularis Tertius

<ul>
 <li>The extensor digitorum longus (EDL) is located <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> to the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> in the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> compartment. The belly of this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> is &quot;sandwiched&quot; between the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and fibularis longus, although the fibularis longus and the EDL are separated by the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> intermuscular septa. Special consideration should be given to the origin of the <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> from tibial tuberosity to the fibular head; this portion of the <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> courses over the deep fibular <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> creating a potential point of <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> entrapment (8). The EDL forms a single tendon <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> to the <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> extensor retinaculum, which then passes deep to the extensor retinaculum of the ankle and divides into 4 superficial tendons wrapped in a synovial sheath. These tendons can be easily seen and palpated on the <a id="dorsal" data-tip="1555" target="_blank" href="/glossary-term/dorsal" class="glossary">dorsum</a> of the foot (extend toes) as they continue to a fairly complicated insertion known as the extensor hood, on the middle and <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> phalanx of toes 2 through 5. The extensor hallucis longus (EHL) originates on the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> half of the tibia courses between the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and EHL, but deep to their larger mass (see cross-section below). The tendon of the EHL enters its own compartment deep to the extensor retinaculum with a separate synovial sheath as it courses to the <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">base</a> of the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> phalanx of the big toe. Like the tendons of the EDL, the tendon of the EHL can be easily palpated and seen with extension of the big toe. The fibularis tertius, if present, will lie just <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> to the EDL on the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> 1/3 of the fibula, or exist as fibers continuous with the EDL, separating into a tendon that courses underneath the extensor retinaculum, but continues directly to the head of the 5th metatarsal. Again, this tendon can be seen with dorsiflexion, eversion, and toe extension and will appear as a 5th EDL tendon that only extends to the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> foot.</li>
</ul>

Where are the Toe Extensor Muscles Located

<ul>
 <li>Palpation of these muscles, as alluded to above, is easiest if you start with the tendons and work your way up. As these tendons are the most superficial structures on the <a id="dorsal" data-tip="1555" target="_blank" href="/glossary-term/dorsal" class="glossary">dorsum</a> of the foot (more accurately, the most superficial dense regular fascial structures), extension of the toes will pop these tendons into the skin making them clearly visible. Trace the tendon from the big toe to the ankle for the EHL, trace the tendons from toes 2 through 5 for the EDL, and if present you may notice a tendon arising from the 5th metatarsal head, the fibularis tertius, crossing in front of the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> malleolus. (The geek in me is saddened by the fact that I do not have a fibularis tertius; but, when I was palpating my own ankle I noticed how easy it was to confuse the fibularis tertius with the tendon of the&#xA0;fibularis brevis, which passes behind the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> malleolus). Once, you have found these tendons and traced them to the ankle you will need to slow down to continue differentiating these tendons as they come together and travel underneath the extensor retinaculum. Have your partner wiggle their toes&#x2026; Have them press toes 2 through 5 down while extending the big toe so that you can feel the EHL tendon distinctly. Having your partner relax and contract will help. You should notice that this tendon continues between the&#xA0;<a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>&#xA0;and EDL into a <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> that disappears about 1/2 way up the tibia. Now do the same for the EDL - big toe down, outer 4 toes up - you should notice that <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> continues up the tibia just <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> to where you palpated the EHL but continues running parallel to the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> all the way up to the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> condyle of the tibia.
 Practically speaking, in a clinical setting the EDL and EHL can be palpated by &quot;falling off&quot; the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> edge of the&#xA0;<a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>. If you fall off the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> about 1/3 the way down the tibia, your fingers will be close to the motor point and belly of the EDL, about halfway down the tibia and a little deeper your fingers will be close to the motor point and <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> belly of the EHL. I recommend using the &quot;tendon up&quot; method a few times before taking this shortcut.
 </li>
</ul>
<a href="https://www.datocms-assets.com/25800/1645302735-gray441.png"><img src="https://www.datocms-assets.com/25800/1645302735-gray441.png" title="The fibularis brevis, fibularis longus, and extensor muscles" alt="Fibularius and toe extensor muscles of the foot"></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 441, Public Domain, https://commons.wikimedia.org/w/index.php?curid=561494

Palpating the EHL, EDL, and Fibularis Tertius

<h4>Extensor Hallucis Longus (EHL):</h4>
<ul>
 <li>Action:
 <ul>
 <li>Extension of the first metatarsophalangeal and interphalangeal joints.</li>
 <li>Dorsiflexion of the ankle, as well as, a weak invertor of the foot and ankle (8,11, 15)</li>
 </ul>
 </li>
</ul>
<h4>Extensor Digitorum Longus (EDL):</h4>
<ul>
 <li>Action:
 <ul>
 <li>Extension of the 2nd through 5th metatarsophalangeal and interphalangeal joints.</li>
 <li>Dorsiflexion of the ankle, as well as, eversion/pronation of the foot and ankle (8, 11)</li>
 </ul>
 </li>
</ul>
<a href="https://www.datocms-assets.com/25800/1645302778-extensor-hallucis-longus.jpeg"><img src="https://www.datocms-assets.com/25800/1645302778-extensor-hallucis-longus.jpeg" title="A cadaver dissection on the front of the foot" alt="Extensor muscle complex of the foot"></a>By Anatomist90 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=25130279
<h4>Integrated Function:</h4>
<ul>
 <li>Stabilization:
 <ul>
 <li>Stabilizes the ankle (tibiotalar), transverse tarsal, tarsometatarsal, metatarsophalangeal and interphalangeal joints (19).</li>
 </ul>
 </li>
 <li>Eccentrically Decelerates:
 <ul>
 <li>The EHL and EDL eccentrically decelerate flexion of the metatarsophalangeal and interphalangeal joints, as well as, eccentrically decelerate plantar flexion of the ankle. These muscles are active from heel strike to foot flat during gait, likely as <a id="synergists" data-tip="1650" target="_blank" href="/glossary-term/synergists" class="glossary">synergists</a> to the&#xA0;<a href="https://brookbushinstitute.com/course/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>&#xA0;(8).</li>
 <li>The EHL will eccentrically decelerate eversion and foot pronation, while the EDL will eccentrically decelerate inversion and foot supination.</li>
 <li>The fibularis tertius will eccentrically decelerate inversion, supination, and plantar flexion.</li>
 </ul>
 </li>
 <li>Synergists:
 <ul>
 <li>The EHL and EDL (and fibularis tertius) work synergistically with the&#xA0;<a href="https://brookbushinstitute.com/course/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>&#xA0;as dorsiflexors of the ankle.</li>
 <li>The EHL may also work synergistically with the t<a href="https://brookbushinstitute.com/course/tibialis-anterior" target="_blank" rel="noopener">ibialis anterior</a>&#xA0;and <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> tibialis to invert, or eccentrically decelerate pronation during gait (8).</li>
 <li>The EDL (and fibularis tertius) may work synergistically as an evertor of the ankle and pronator of the foot along with the&#xA0;Fibularis (Peroneal)&#xA0;muscles.</li>
 <li>A more obvious synergistic relationship exists between the EHL, EDL, extensor hallucis brevis (EHB), and extensor digitorum brevis (EDB) in extending the metatarsophalangeal joints of all toes except toe 5.</li>
 </ul>
 </li>
</ul>
<a href="https://www.datocms-assets.com/25800/1645302816-tibialis-anterior-picture.png"><img src="https://www.datocms-assets.com/25800/1645302816-tibialis-anterior-picture.png" title="Cross-sectional view showing the muscles of the fibula and tibia" alt="Cross-sectional view of the fibula and tibia muscles"></a>
Henry Gray (1918) Anatomy of the Human Body (See &quot;Book&quot; section below) Bartleby.com: Gray&apos;s Anatomy, Plate 440

Toe Extensor Actions

<ul>
 <li>Although the EHL and EDL cross several joints,&#xA0; it is hard to imagine that these muscles are producing enough force from their relatively <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> attachment to have a significant effect on the <a id="arthrokinematics" data-tip="1859" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematics</a> of any joints other than the metatarsophalangeal and interphalangeal joints. In fact, it is my <a id="hypothesis" data-tip="1446" target="_blank" href="/glossary-term/hypothesis" class="glossary">hypothesis</a> that the EHL and EDL contribute to the lack of talar <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> noted in those individuals with <a href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener">Lower Leg Dysfunction (LLD)</a> (those individuals lacking dorsiflexion) by acting as <a href="https://brookbushinstitute.com/article/overactive-synergists-cheat-sheet" target="_blank" rel="noopener">over-active synergists</a> for an inhibited <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a> - in essence, the loss of force production by the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> (a <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> capable of <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> migration of the navicular and accompanying talar <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> tilt) and the compensation by the EHL and EDL (muscles not capable of acting on the talus at all) leads to insufficient force on the talus to maintain <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> mechanics.</li>
 <li>The EHL and EDL are capable of <a id="dorsal" data-tip="1554" target="_blank" href="/glossary-term/dorsal" class="glossary">dorsal</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> of the metatarsophalangeal and interphalangeal joints. Often, over-activity of these muscles will lead to <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>, a loss of <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a>, and contribute to pronation distortion (<a href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener">Lower Leg Dysfunction (LLD)</a>). Clinically, I have found manual mobilization/manipulation of these joints to be effective in reducing <a id="tone" data-tip="1639" target="_blank" href="/glossary-term/tone" class="glossary">tone</a> and over-activity of the EHL and EDL.</li>
 <li>The fibularis tertius is capable of a <a id="dorsal" data-tip="1554" target="_blank" href="/glossary-term/dorsal" class="glossary">dorsal</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> of the 5th metatarsal head.</li>
</ul>
<a href="https://www.datocms-assets.com/25800/1645302867-toldt_630_medium.jpeg"><img src="https://www.datocms-assets.com/25800/1645302867-toldt_630_medium.jpeg" title="The attachment of the extensor digitorum longus on the foot" alt="Distal attachment of the EDL"></a>Note the complicated <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> attachment of the EDL - https://dspace.creighton.edu/xmlui/bitstream/handle/10504/16999/toldt_630_medium.jpg?sequence=2

My Fascial Hypothesis: Large fascial sheaths not only play a role in the transmission of mechanical force but may also play a role in dictating the function of muscular synergies. This is likely caused by reducing or increasing <a id="tone" data-tip="1639" target="_blank" href="/glossary-term/tone" class="glossary">tone</a> of invested musculature via reflex arcs formed between mechanoreceptors embedded in the <a id="connective-tissue-cell" data-tip="1368" target="_blank" href="/glossary-term/connective-tissue-cell" class="glossary">connective tissue</a> and the attached musculature. In this way my view of fascia differs slightly from noted expert on the subject Tom Myers. I think of these large fascial sheaths (specifically the thoracolumbar fascia, iliotibial band, and abdominal fascial sheath) as nature&apos;s &quot;motherboard.&quot; A place for mechanical information to be communicated to the <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> for more efficient recruitment of the <a id="muscular-system" data-tip="1691" target="_blank" href="/glossary-term/muscular-system" class="glossary">muscular system</a>. Despite having a slightly different philosophy it does not change the fact that fascia plays an important communicative role in the human body and we have Tom Myers to thank for his work.
<a href="https://www.datocms-assets.com/25800/1644872934-fascia-web-in-body.jpeg"><img src="https://www.datocms-assets.com/25800/1644872934-fascia-web-in-body.jpeg" title="Image of the fascial system of the body connecting muscles" alt="The fascial web connecting two muscle fascicles"></a>
<h4>Fascial Integration of the EHL, EDL, and Fibularis Tertius</h4>
<ul>
 <li>I find it interesting that the EDL, an evertor/pronator of the foot/ankle shares an intermuscular septum with the fibularis longus, the primary evertors of the foot/ankle - while the EHL, an invertor/supinator of the foot/ankle shares the interosseous membrane with the <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> tibialis, a strong invertor/supinator of the foot ankle.</li>
 <li>Tom Myers describes a &quot;branch&quot; of the &quot;superficial front line&quot; that continues from the iliotibial band to the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> tibiofibular ligament to the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> crural compartment (6), however, I think more <a id="specificity" data-tip="1223" target="_blank" href="/glossary-term/specificity" class="glossary">specificity</a> can be drawn from this line based on both anatomical relationships and common motor behavior in <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> dysfunction. Commonly the <a href="https://brookbushinstitute.com/courses/tensor-fascia-latae-tfl" target="_blank" rel="noopener">tensor fascia latae (TFL)</a> and EDL are over-active, while the <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a> is most commonly under-active. The EHL, although commonly over-active, originates too <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> to be anatomically linked. This leaves a potential fascial synergy between the TFL and EDL via the ITB. They have the highest likelihood of being fascially linked by the iliotibial band (ITB) via fascial slips of the ITB that invest in the tibial tuberosity and those that continue on to invest in the <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> tibiofibular ligament - a.k.a. the origin of the EDL.</li>
 <li>The fibularis tertius would share a fascial connection with the fibularis brevis via the tendinous insertion into the 5th metatarsal head. It may be worth exploring this relationship in those individuals who excessively pronate, and/or complain of pain in the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> foot and 5th metatarsal head. Often pain emanating from this region is related to <a id="hypermobility" data-tip="1677" target="_blank" href="/glossary-term/hypermobility" class="glossary">hypermobility</a> of this joint and the <a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">release</a> of fibularis muscles may reduce excessive motion.</li>
</ul>
<img src="https://www.datocms-assets.com/25800/1645303017-edl-and-ehl-cadaver.png" title="A cadaver dissection of the EDL, EHL, and fibularis tertius" alt="The tendons of the EDL, EHL, and Fibularis Tertius">Notice the tendons of the EDL on the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> aspect of the foot, contributing to eversion, and the fibularis tertius as a separate tendon extending from the same <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> mass - http://www.rvuanatomy.com/uploads/1/3/4/5/13457421/ac1a-animated.gif

These muscles fall into the weird category of long, but over-active. This is a relationship we usually note in <a href="https://brookbushinstitute.com/article/overactive-synergists-cheat-sheet" target="_blank" rel="noopener">over-active synergists</a>, and that is precisely the role that the EDL and EHL play (The fibularis tertius would play a similar role).
In <a href="https://brookbushinstitute.com/courses/upper-body-dysfunction-ubd" target="_blank" rel="noopener">Upper Body Dysfunction (UBD)</a> the EDL and EHL play no significant role.
In <a href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">Lumbo Pelvic Hip Complex Dysfunction (LPHCD)</a> and Sacroiliac Joint Dysfunction (SIJD), the EDL and EHL play no significant role.
In <a href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener">Lower Leg Dysfunction (LLD)</a>,
<ul>
 <li>B2&apos;s Rules of Human Movement Science
 <ul>
 <li>Rule #5: Every inhibited <a id="prime-mover" data-tip="1662" target="_blank" href="/glossary-term/prime-mover" class="glossary">prime mover</a> will result in <a id="synergistic-dominance" data-tip="1643" target="_blank" href="/glossary-term/synergistic-dominance" class="glossary">synergistic dominance</a> of the ancillary movers for that joint action.</li>
 </ul>
 </li>
</ul>
The EHL and EDL become <a id="synergistic-dominance" data-tip="1649" target="_blank" href="/glossary-term/synergistic-dominance" class="glossary">synergistically dominant</a> for an inhibited <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a>. That is to say that the overactive gastrocnemius/soleus complex results in altered <a id="reciprocal-inhibition" data-tip="1655" target="_blank" href="/glossary-term/reciprocal-inhibition" class="glossary">reciprocal inhibition</a> of the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and a relative increase in EHL and EDL activity to <a id="compensation-pattern" data-tip="1697" target="_blank" href="/glossary-term/compensation-pattern" class="glossary">compensate</a>. This increase in activity occurs despite the implication that a loss in dorsiflexion implies an increase in length of the EHL and EDL. This may also lead to <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>, as over-activity may lead to a <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> of the metatarsophalangeal and interphalangeal joints. The change in <a id="arthrokinematics" data-tip="1859" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematics</a> may limit flexion and/or extension of the toes. Particularly problematic is the loss of toe extension that may result in a <a id="compensation-pattern" data-tip="1696" target="_blank" href="/glossary-term/compensation-pattern" class="glossary">compensation pattern</a> that includes pronation (eversion) from heel-off to toe-off during the stance phase of gait, and pronation during any activity that requires an individual to move on the &quot;balls&quot; or their feet (baseball swing, golf, changing direction, jumping, etc.).
In short, the EHL and EDL are long and over-active, acting as <a href="https://brookbushinstitute.com/article/overactive-synergists-cheat-sheet" target="_blank" rel="noopener">overactive synergists</a>. This implies these muscles should be <a id="release" data-tip="1253" target="_blank" href="/glossary-term/release" class="glossary">released</a>, however, self-administered techniques have proven relatively ineffective. The major obstruction being the patient/client&apos;s ability to differentiate between the <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a> and the EDL/EHL. It can be very frustrating to add &quot;EHL/EDL Self-administered <a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">Release</a> with Tennis Ball&quot; to a home exercise program, only to find that the client/patient spent the week between appointments <a id="release" data-tip="1250" target="_blank" href="/glossary-term/release" class="glossary">releasing</a> their tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> resulting in no carry-over from session-to-session when re-assessing active dorsiflexion&#x2026;. aaaaaaaahhhhhhhhh!
Where you will see the EHL and EDL mentioned during exercise programs in the <a href="http://www.brookbushinstitute.com/" target="_blank" rel="noopener">Brookbush Institute of Human Movement Science</a> content is in the cue &quot;toes down&quot; during <a href="https://brookbushinstitute.com/courses/tibialis-anterior-activation" target="_blank" rel="noopener">tibialis </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> activation. This cue is used to reciprocally inhibit the EHL and EDL to reduce the chance that these muscles will continue to be <a id="synergistic-dominance" data-tip="1649" target="_blank" href="/glossary-term/synergistic-dominance" class="glossary">synergistically dominant</a> during exercises aimed at improving recruitment, neuromuscular control, and conditioning of the tibialis <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a>.
<h4>Clinical Implications:</h4>
<ul>
 <li>Hallux Rigidus</li>
 <li>Arthritis of Toes</li>
 <li>Metatarsalgia</li>
 <li>Peroneal <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> entrapment (at fibular head)</li>
 <li>Plantar Fasciitis</li>
 <li>Achilles tendonitis (long term over-activity = rupture)</li>
 <li>Ankle impingement</li>
 <li>MTSS (<a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">Medial</a> tibial stress syndrome)</li>
 <li><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> tibialis tendonitis</li>
 <li>Fibularis tendonitis</li>
</ul>
<h4>Signs of Altered Length/Tension and Tone:</h4>
<ul>
 <li><a href="https://brookbushinstitute.com/courses/solutions-table-overhead-squat-assessment" target="_blank" rel="noopener">Overhead Squat:</a>
 <ul>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-4-feet-flat-breakdown" target="_blank" rel="noopener">Feet Flatten</a> - Long/Over-active</li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-5-feet-turn-out-breakdown" target="_blank" rel="noopener">Feet Turn Out</a> - Long/Over-active</li>
 <li>Toes extend - Long/Over-active (This sign is not normally listed on the <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> template, but is worth noting)</li>
 </ul>
 </li>
 <li>Goniometric Assessment:</li>
 <li>Toe Extension &lt; 70&#xB0; (0&#xB0; of extension of the IP&apos;s)</li>
 <li>Toe Flexion &lt; 90&#xB0; (the <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> phalanx forms a roughly 90&#xB0; angle with the plane of the tarsal bones)</li>
</ul>
<h3>EHL and EDL Trigger Points</h3>
<ul>
 <ul>
 <li>
 Palpation results in tenderness (<a id="trigger-point" data-tip="1634" target="_blank" href="/glossary-term/trigger-point" class="glossary">trigger points</a> or <a id="latent-trigger-point" data-tip="1134" target="_blank" href="/glossary-term/latent-trigger-point" class="glossary">tender points</a>) and may result in radiating symptoms along with the <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> and its tendons. Based on the theoretical <a id="model" data-tip="1469" target="_blank" href="/glossary-term/model" class="glossary">model</a> of <a id="trigger-point" data-tip="1632" target="_blank" href="/glossary-term/trigger-point" class="glossary">trigger point</a> development (8) it would seem likely that &#x201C;trigger points&#x201D; are dysfunctional at the &#x201C;motor point&#x201D; of a <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a>. You may find the motor point map created by this research study helpful in directing patients/clients to the appropriate location &#x2013; <a href="https://brookbushinstitute.com/article/motor-point-map" target="_blank" rel="noopener">Motor Point Map</a>
 </li>
 </ul>
</ul>
<a href="https://www.datocms-assets.com/25800/1645303057-ehl-edl-triugger-points.jpeg"><img src="https://www.datocms-assets.com/25800/1645303057-ehl-edl-triugger-points.jpeg" title="Common trigger points of the extensor muscles" alt="Trigger points of the extensor digitorum longus and extensor hallucis longus"></a>
David G. Simons, Janet Travell, Lois S. Simons, Travell &amp; Simmons&#x2019; Myofascial Pain and Dysfunction, The <a id="trigger-point" data-tip="1632" target="_blank" href="/glossary-term/trigger-point" class="glossary">Trigger Point</a> Manual, Volume 1. Upper Half of Body: Second Edition,&#xA9; 1999 Williams and Wilkens

Postural Dysfunction and the Toe Extensors

Exercises and Techniques for the EHL, EDL, and Fibularis Tertius

Equipment-Free, Variation: Standing Tibialis Anterior Activation

This technique is far easier to set-up and increases carry-over dramatically; however, you need access to a massage table or plint and a &quot;monster band&quot;.
<iframe src="https://player.vimeo.com/video/104186038" frameborder="0" allowfullscreen="allowfullscreen"></iframe>
<h4>Tibialis Anterior Activation on a Table (reinforcing Heel Strike Mechanics):</h4>
<ol>
 <li>Place the band over the foot, close to the ankle.</li>
 <li>Ask your patient/client to dorsiflex and invert the ankle while flexing the toes.
 <ul>
 <li>Note: I prefer a 2:4:2 count (E:I:C) on this exercise to emphasize increasing strength at the new end range achieved with the ankle <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a> exercises that preceded this activity.</li>
 </ul>
 </li>
 <li>While performing step 3, you can reinforce &quot;heel strike synergy&quot; by cueing quadriceps activation (locking the knee) and <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a> activation (pressing the heel into the table or a towel placed under the heel).</li>
 <li>Adjust the resistance so that 12-20 reps may be performed with <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a>.
 <ul>
 <li>Progression:
 <ul>
 <li>This exercise may be progressed by using a stronger band.</li>
 </ul>
 </li>
 <li>Common mistakes:
 <ul>
 <li>Trying to pull the band up with the whole leg: It is advisable to reinforce quadriceps activation (locking the knee) and <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a> activation (pressing the heel into the table or a towel placed under the heel). Try to prevent the individual from using hip flexion and knee flexion to assist in pulling on the band, which may result in reinforcing compensation patterns that include <a href="https://brookbushinstitute.com/courses/tensor-fascia-latae-tfl" target="_blank" rel="noopener">tensor fasciae latae</a> or <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> over-activity.</li>
 </ul>
 </li>
 </ul>
 </li>
</ol>

 Tibialis Anterior Activation on a Table (reinforcing Heel Strike Mechanics)

Heel Walks

<ol>
 <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>Donald A. Neumann, &ldquo;Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation &ndash; 2nd Edition&rdquo; &copy; 2012 Mosby, Inc.</li>
 <li>Michael A. Clark, Scott C. Lucett, NASM Essentials of Personal Training: 4th Edition, &copy; 2011 Lippincott Williams and Wilkins</li>
 <li>Leon Chaitow, Muscle Energy Techniques: Third Edition, &copy; Elsevier 2007</li>
 <li>Tom Myers, Anatomy Trains: Second Edition. &copy; Elsevier Limited 2009</li>
 <li>Shirley A Sahrmann, Diagnoses and Treatment of Movement Impairment Syndromes, &copy; 2002 Mosby Inc.</li>
 <li>David G. Simons, Janet Travell, Lois S. Simons, Travell &amp; Simmons&rsquo; Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition,&copy; 1999 Williams and Wilkens</li>
 <li>Cynthia C. Norkin, D. Joyce White, Measurement of Joint Motion: A Guide to Goniometry &ndash; Third Edition. &copy; 2003 by F.A. Davis Company</li>
 <li>Cynthia C. Norkin, Pamela K. Levangie, Joint Structure and Function: A Comprehensive Analysis: Fifth Edition &copy; 2011 F.A. Davis Company</li>
 <li>Florence Peterson Kendall, Elizabeth Kendall McCreary, Patricia Geise Provance, Mary McIntyre Rodgers, William Anthony Romani, Muscles: Testing and Function with Posture and Pain: Fifth Edition &copy; 2005 Lippincott Williams &amp; Wilkins</li>
 <li>Brent Brookbush, Fitness or Fiction: The Truth About Diet and Exercise &copy; 2011 Brent Brookbush - http://www.amazon.com/Fitness-Fiction-Truth-About-Exercise/dp/0615503012</li>
 <li>Carolyn Richardson, Paul Hodges, Julie Hides. Therapeutic Exercise for Lumbo Pelvic Stabilization &ndash; A Motor Control Approach for the Treatment and Prevention of Low Back Pain: 2nd Edition (c) Elsevier Limited, 2004</li>
 <li>Andrew Biel, Trail Guide to the Human Body: 4th Edition, &copy; 2010</li>
 <li>Bayer T, Kolodziejski N, Flueckiger G. (2014). The extensor hallucis capsularis tendon &ndash; a prospective study of its occurrence and function. Foot and Ankle Surgery. 20: 192-194.</li>
 <li>Lui TH. (2011). Extensor tendoscopy of the ankle. Foot and Ankle Surgery. E1-e6.</li>
 <li>Ma H, Zhao J, Yu B, Ye B. (2014). A gross anatomic study of distal tibia and fibula for single-incision approach. Journal of Orthopaedic Surgery and Research. 9:28.</li>
 <li>Yildiz S, Yalcin B. (2012). A unique variation of the peroneus tertius muscle. Surg. Radiol. Anat. 34: 661-663.</li>
 <li>Cimadoro G, Paizis C, Alberti G, Babault N. (2013). Effects of different unstable supports on EMG activity and balance. Neuroscience Letters. 548: 228-232.</li>
</ol>

Bibliography

© 2016 Brent Brookbush
Questions, comments, and criticisms are welcome and encouraged

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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