Sartorius muscle

At a glance

English

Sartorius muscle

Latin (TA2)

Musculus sartorius

System

Muscle

Region

Lower limb

Side

Paired, left and right

About the sartorius muscle

The sartorius is a narrow, ribbon-like muscle that crosses the front of the thigh diagonally from the hip to the inner side of the knee. No muscle in the body is longer, and it lies just under the skin and fascia of the anterior thigh compartment. Its name comes from the Latin for tailor, after the cross-legged sitting posture once used by tailors.

It begins at the anterior superior iliac spine plus the upper part of the notch below it. From there it slants down and inward across the thigh, curves behind the femur's medial condyle, and becomes a flat tendon that turns forward to attach to the upper medial surface of the tibia. There it joins the tendons of gracilis and semitendinosus to form the pes anserinus.

The muscle is an important landmark. Its upper part forms the femoral triangle's lateral side, and the spot where it crosses the adductor longus marks the triangle's lower point. Lower down it roofs over the adductor canal, the passage that carries the femoral artery and vein, the saphenous nerve and the nerve to vastus medialis. It is supplied by the femoral nerve, like the other anterior thigh muscles.

Sartorius acts on both hip and knee, but each action is weak, so it mainly assists other muscles. At the hip it flexes, abducts and laterally rotates the thigh; at the knee it flexes the leg and, once the knee is bent, turns the leg medially. Placing the heel of one foot on the opposite knee uses all of these actions together. A bursa under the pes anserinus can become inflamed with overuse, giving pain and tenderness on the inner side of the knee, a condition known as pes anserine bursitis.

Attachments, action and supply

Origin

Anterior superior iliac spine and the upper part of the notch just below it.

Insertion

Upper medial surface of the tibia, as part of the pes anserinus.

Action

Flexes, abducts and laterally rotates the hip; flexes the knee and medially rotates the flexed leg.

Nerve supply

Femoral nerve (L2, L3).

Blood supply

Muscular branches of the femoral artery, including branches from the lateral circumflex femoral and descending genicular arteries.