Sartorius muscle

Sartorius muscle
Muscles of lower extremity. (Rectus femoris removed to reveal the vastus intermedius.)
Latin	musculus sartorius
Gray's	subject #128 470
Origin	inferior to the anterior superior iliac spine
Insertion	anteromedial surface of the upper tibia in the pes anserinus
Artery	femoral artery
Nerve	femoral nerve (sometimes from the intermediate cutaneous nerve of thigh)
Actions	Flexion, abduction, and lateral rotation of the hip, flexion of the knee[1]

The Sartorius muscle – the longest muscle in the human body – is a long thin muscle that runs down the length of the thigh. Its upper portion forms the lateral border of the femoral triangle.

Origin and insertion

The sartorius muscle arises by tendinous fibres from the anterior superior iliac spine, running obliquely across the upper and anterior part of the thigh in an inferomedial direction.

It descends as far as the medial side of the knee, passing behind the medial condyle of the femur to end in a tendon.

This tendon curves anteriorly to join the tendons of the gracilis and semitendinous muscles which together form the pes anserinus, finally inserting into the proximal part of the tibia on the medial surface of its body.

Etymology

Sartorius comes from the Latin word sartor, meaning tailor,^[2] and it is sometimes called the tailor's muscle.

There are four hypotheses as to the genesis of the name: One is that this name was chosen in reference to the cross-legged position in which tailors once sat. Another is that it refers to the location of the inferior portion of the muscle being the "inseam" or area of the inner thigh tailors commonly measure when fitting a pant. A third is that the muscle closely resembles a tailor's ribbon. Additionally, antique sewing machines required continuous cross body pedalling. This combination of lateral rotation and flexion of the hip and flexion of the knee gave tailors particularly enlarged sartorius muscles.

Actions

Assists in flexion, abduction and lateral rotation of hip, and flexion of knee.^[1] Looking at the bottom of one's foot, as if checking to see if one had stepped in gum, demonstrates all four actions of sartorius.

Innervation

Situated in the anterior fascial compartment of the thigh, the sartorius is innervated via the anterior (or superficial) branch of the femoral nerve (AORN Journal, J. Murauski). The femoral nerve is responsible for both sensory and motor components in the sartorius and provides proprioceptive feedback for the muscle (Anatomy and Physiology 5th edition, K. Saladin)

Pathology

One of the many conditions that can disrupt the use of the sartorius is pes anserine bursitis, an inflammatory condition of the medial portion of the knee. This condition usually occurs in athletes from overuse and is characterized by pain, swelling and tenderness. The pes anserinus is made up from the tendons of the gracilis, semitendinosus, and sartorius muscles; these tendons attach on to the anteromedial proximal tibia. When inflammation of the bursa underlying the tendons occurs they separate from the head of the tibia (eMedicine, MD. M. Glencross).

Variations

Slips of origin from the outer end of the inguinal ligament, the notch of the ilium, the ilio-pectineal line or the pubis occur.

The muscle may be split into two parts, and one part may be inserted into the fascia lata, the femur, the ligament of the patella or the tendon of the Semitendinosus.

The tendon of insertion may end in the fascia lata, the capsule of the knee-joint, or the fascia of the leg.

The muscle may be absent (Scott-Conner, Carol E. H.; David L. Dawson (2003). Operative Anatomy. Lippincott Williams & Wilkins. ISBN 0781735297. http://books.google.com/books?id=06GvkEYPg20C.  p.606).

Additional images

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  Bones of the right leg. Anterior surface.

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  Structures surrounding right hip-joint.

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  Muscles of the iliac and anterior femoral regions.

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  Cross-section through the middle of the thigh.

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  Muscles of the gluteal and posterior femoral regions.

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  Femoral sheath laid open to show its three compartments.

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  The left femoral triangle.

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  The lumbar plexus and its branches.

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  Front and medial aspect of right thigh.

References

1. ^ ^{a b} Moore, Keith; Anne Agur (2007). Essential Clinical Anatomy. Lippincott Williams & Wilkins. pp. 334. ISBN 0-7817-6274-X. 
2. ^ Mosby’s Medical, Nursing and Allied Health Dictionary, Fourth Edition, Mosby-Year Book Inc., 1994, p. 1394

External links

• 208339022 at GPnotebook
• LUC sart
• SUNY Labs 14:st-0407
• Cross section at UV pembody/body15a
• Cross section at UV pelvis/pelvis-e12-15

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.