What is the X in X-mas?
sartorius muscle sar·to·ri·us muscle (sär-tôr'ē-əs)
A muscle with origin from the anterior superior spine of the ilium, with insertion into the medial border of the tuberosity of the tibia, with nerve supply from the femoral nerve, and whose action flexes the thigh and leg and rotates the leg medially and the thigh laterally. Also called tailor's muscle.
(from the Latin sartor, "mender"), long, narrow, ribbonlike thigh muscle beginning at the front of the crest of the pelvic girdle, extending obliquely down the front and side of the thigh, and inserted at (attached to) the inner and upper portion of the tibia (shinbone). It received its name because it is especially useful in assuming the cross-legged position that ancient tailors used in their work