Muscle · Hips

Sartorius

Musculus sartorius

Sartorius is the longest muscle in the body — a narrow strap that runs all the way from the bony point at the front of the pelvis, diagonally across the thigh, to the inside of the shin below the knee. Its name comes from sartor, Latin for tailor, because the four things it does at once are the four things that put you in the old cross-legged tailor's sitting position: it bends the hip, takes the thigh out to the side, turns it outwards, and bends the knee. It is not strong at any of them on its own; it assists. What makes it matter is where it lies. It forms the outer edge of the femoral triangle in the groin and roofs the canal the femoral artery travels down, and at its far end it joins gracilis and semitendinosus in the pes anserinus on the inner shin — a common site of tenderness that gets mistaken for the knee joint itself.