Human Movement Science & Functional Anatomy of the:

Sartorius

by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS

Sartorius Muscle and the Femoral Triangle http://www.rvuanatomy.com/uploads/1/3/4/5/13457421/afc3b_animated.gif

What's in a name:

• Sartorius - originating from the latin root "sartor" meaning "tailor". Although there may are several stories describing the origin of this word I prefer the story that describes the position assumed by tailor's with one ankle over opposite knee - This position is attained by the same combination of joint actions the sartorius is capable of.
• An interesting fact: The sartorius is the longest muscle in the human body.

Pes Anserinus Tendon - Netter Anatomy Atlas - http://webmedia.unmc.edu/medicine/todd/dissection/idg33hipknee/p0488pesanserinus.jpg

Sartorius:

• Origin: Anterosuperior iliac spine, superior half of the notch just distal to the spine, an lateral portion of the inguinal ligament (3, 11).
• Insertion: Proximal part of the medial surface of the tibia near the anterior border, making up the most medial fibers of the pes anserinus tendon, passing over the pes anserinus bursa (11).
  • The sartorius is covered by the anterior fascia lata, and although it is considered to exist within the anterior compartment (between medial and lateral intermuscular septa), this muscle is nearly enveloped by the anterior fascia lata in it's own compartment. There are no structures that lie anterior to this muscle, but posteriorly the muscle covers the rectus femoris at its insertion and courses obliquely (inferior/medial direction) over the vastus medialis, creating the inferior border of the femoral triangle, superficial border of the adductor canal and abutting the medial intermuscular septa at the knee.
  • Palpation of this muscle can be achieved by having your partner lie supine and cross one ankle over opposite knee (FABER Test Position). Place your hand over the medial thigh and ask your patient to raise their knee toward the ceiling. You will feel the slender sartorius pop into your hands. You can then trace the sartorius along its length from medial knee to ASIS (14).
• Nerve: Femoral nerve via the lumbar plexus originating from nerve roots L2 and L3, sometimes L4.
• Action:
  • Hip: Flexion, external rotation and slight abduction
  • Knee: Flexion and tibial internal rotation

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Integrated Function:

• Stabilization:
  • Stabilization of the hip
  • Stabilization of the tibiofemoral joint
• Eccentrically Decelerates:
  • Knee extension and tibial external rotation
  • Hip extension, internal rotation and adduction
• Synergists:
  • As one of the muscles of the Pes Anserinus Group, the sartorius contributes tibial internal rotation and flexion along with the gracilis and semitendinosus . It should be noted that the semimembranosus , medial gastrocnemius and popliteus may also contribute to this action.
  • As a hip flexor the sartorius works synergistically with the rectus femoris,  psoas , iliacus , tensor fasciae latae (TFL)  and anterior adductors .
  • Although it may not be an active or purposeful synergy, over-activity and adaptive shortening of the sartorius may deflect the femur into abduction during hip extension past neutral along with a short/over-active rectus femoris and TFL . This is most notable in Lower Leg Dysfunction (LLD) , Lumbo Pelvic Hip Dysfunction (LPHCD) , or Sacroiliac Joint Dysfunction (SIJD) and is often related to hip and/or knee pain. A common sign of this "dysfunctional synergy" in a gym setting is abduction of the back leg during the eccentric phase of sagittal plane lunge.

Sartorius - http://www.schoolofthaimassage.com/resources/tym-for-self-healing

Arthrokinematics:

• This muscle plays a role in the arthrokinematics of the knee and hip joints.
  • Hip: The sartorius may contribute to anterior and superior glide of the femoral head and external rotation.
  • Knee: The sartorius may contribute to compression of the medial compartment, a varus force (resist valgus force), posterior glide of the tibia, and tibial internal rotation (3).

Sartorius at medial knee – http://www.sciencephoto.com/online-courses/online-courses/image/454917/350wm/C0126318-cadaver_dissection-SPL.jpg

Fascial Integration:

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 tone of invested musculature via reflex arcs formed between mechanoreceptors imbedded in the connective tissue 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 natures "mother board." A place for mechanical information to be communicated to the nervous system for more efficient recruitment of the muscular system. 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.

Medial Knee with Patellar Tendon, LCL and Pes Anserinus Tendons attached – http://www.visionmedicavirtual.com/online-courses/online-courses/gallery/b_IS.0908.001.08.jpg

Fascial Integration of the Rectus Femoris:

• Proximal Attachment: At the proximal attachment the sartorius may or may not be involved in fascial relationships. Despite an origin that abuts the tensor fasciae latae  and investment in the inguinal ligament their are no obvious relationships. Scouring various texts and searching for more detailed dissections did not reveal much. Even Tom Myer's Anatomy Trains makes no specific mention of the Sartorius as part of the "fascial trains" (6). The investment of the sartorius into the inguinal ligament does inspire questions on whether tension in this fascial structure affects sartorius activity. If this is the case then activity of the adductor longus , rectus abdominis , external obliques , internal obliques , transverse abdominis and potentially increased tension in the fascia lata itself may affect sartorius activity. I had hoped that the "functional relationship" between the sartorius, TFL , and rectus femoris discussed above in "Synergies" would reveal itself as a group of muscles fascially intertwined at the anterior ilium, but this is does not seem to be the case.
• Distal Attachment: At the distal attachment the most obvious fascial relationship is via the pes anserinus tendon. The gracilis , semitendinosus and sartorius all contribute to knee flexion and tibial internal rotation as mentioned above in "Synergies." Although I could not find a specific reference to relationship with the knee ligaments I am curious to find out whether fascial slips exist between the pes anserinus tendon, MCL and/or medial retinaculum. If this is the case, dysfunction and increased tension in knee ligaments may be part of the dysfunctional patterns of pes anserinus muscle activity noted in conjunction with arthrokinematic dyskinesis at the knee.

Cadaver dissection of the lower extremity – http://myampgoesto11.tumblr.com/online-courses/online-courses/post/16940081948/day-5-of-cadaver-dissection

Behavior in Postural Dysfunction:

This muscle is a quandary in postural dysfunction. Although its role as a hip flexor in lumbo pelvic hip complex dysfunction would imply that this muscle is prone to adaptive shortening and over-activity; the sartorius also plays a role in both hip external rotation and tibial internal rotation implying a adaptive lengthening and under-activity in lower leg dysfunction.

In Upper Body Dysfunction (UBD)  the sartorius plays no significant role.

In Lumbo Pelvic Hip Complex Dysfunction (LPHCD)  the sartorius is short and over-active as a hip flexor, contributing to the anterior pelvic tilt seen in this dysfunction. In Sacroiliac Joint Dysfunction (SIJD)  the ability to both flex the hip and externally rotate the hip leads to inference of over-activity on both sides. That is to say that over-activity is implied on the side that presents with a relatively posteriorly rotated innominate (in conjunction with relative external rotation of the hip), and on the side presenting with a relatively anteriorly rotated innominate (in conjunction with relative hip flexion). As the self-administered release technique (foam rolling) that affects the sartorius also affects the rectus femoris , it is unlikely that I would address both sides. Instead, I would likely look for trigger points higher in the thigh (location of sartorius trigger points when using self-administered rectus femoris release) of the anteriorly rotated side in conjunction with rectus femoris release indicated for this dysfunction.

In Lower Leg Dysfunction (LLD)  the sartorius should be lengthened by relative hip internal rotation and tibial external rotation, implying adaptive lengthening and under-activity. However, specific activation techniques do not exist for this muscle as it plays an accessory role in joint actions that may increase activity of over-active synergists . Tibial internal rotator activation may be somewhat effective for increasing sartorius activity, however, the position used in this technique is not ideal for increasing activity of this muscle specifically. Further complicating the categorization of relative length and activity of this muscle is the often seen variation of lower leg dysfunction - "knees bow out" . The functional synergy between the rectus femoris , TFL and sartorius discussed above would imply over-activity of this muscle.

In short, this is a muscle that is probably best addressed with release techniques alone. As stretching techniques may disrupt knee mechanics and specific activation may result in increasing the activity of over-active muscles they are not recommended. From the perspective of self-administered techniques, awareness of sartorius trigger point location when performing rectus femoris release, and awareness of the sartorius' role in tibial internal rotator activation may be helpful.

Clinical Implications:

• * Hip impingement
  • Arthrokinematic dysfunction of the hip
  • Anterior knee pain
  • Chondromalacia Patella
  • Pes anserinus tendonitis
  • Pes anserinus bursitis
  • Medial knee pain
  • Anterior hip pain and/or ASIS pain resulting from over-activity and triger points.

Signs of Altered Length/Tension and Tone:

• Overhead Squat:
  • Anterior Pelvic Tilt: Short/Over-active
  • Excessive Forward Lean: Short/Over-active
  • Knees Bow Out: Short/Over-active
  • Knees Bow In: Long Underactive
  • Feet Turn Out: Long/Under-active
• Goniometric Assessment
• * Decreased Tibial Internal Rotation < 20°
  • Decreased Hip Internal Rotation Approximately < 45°
  • Decreased Hip Extension < 10-15°
• Specific Flexibility Assessment
  • Thomas Test
• Palpation of the Sartorius:
  • See image below for common trigger point locations and referral pain pattern for active trigger points.

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Exercises involving the Sartorius:

Rectus Femoris Self-administered Static Release (Note: Trigger points felt in this technique may actually be sartorius trigger points)

Anterior Thigh Self-administered Active Release (Note: Restrictions felt in this technique may actually be related to the sartorius)

Tibial Internal Rotator Activation:

Bibliography:

• 3. Phillip Page, Clare Frank , Robert Lardner , Assessment and Treatment of Muscle Imbalance: The Janda Approach © 2010 Benchmark Physical Therapy, Inc., Clare C. Frank, and Robert Lardner
  1. Dr. Mike Clark & Scott Lucette, “NASM Essentials of Corrective Exercise Training” © 2011 Lippincott Williams & Wilkins
  2. Donald A. Neumann, “Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation – 2nd Edition” © 2012 Mosby, Inc.
  3. Michael A. Clark, Scott C. Lucett, NASM Essentials of Personal Training: 4th Edition, © 2011 Lippincott Williams and Wilkins
  4. Leon Chaitow, Muscle Energy Techniques: Third Edition, © Elsevier 2007
  5. Tom Myers, Anatomy Trains: Second Edition. © Elsevier Limited 2009
  6. Shirley A Sahrmann, Diagnoses and Treatment of Movement Impairment Syndromes, © 2002 Mosby Inc.
  7. David G. Simons, Janet Travell, Lois S. Simons, Travell & Simmons’ Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition,© 1999 Williams and Wilkens
  8. Cynthia C. Norkin, D. Joyce White, Measurement of Joint Motion: A Guide to Goniometry – Third Edition. © 2003 by F.A. Davis Company
  9. Cynthia C. Norkin, Pamela K. Levangie, Joint Structure and Function: A Comprehensive Analysis: Fifth Edition © 2011 F.A. Davis Company
  10. 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 © 2005 Lippincott Williams & Wilkins_
  11. Brent Brookbush, Fitness or Fiction: The Truth About Diet and Exercise © 2011 Brent Brookbush - http://www.amazon.com/Fitness-Fiction-Truth-About-Exercise/dp/0615503012
  12. 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
  13. Andrew Biel, Trail Guide to the Human Body: 4th Edition, © 2010

© 2014 Brent Brookbush

Questions, comments, and criticisms are welcome and encouraged