Long and thin, the sartorius muscle spans the distance of the thigh. It originates at anterior superior iliac spine (a bony projection on the uppermost part of the pelvis) and travels to the upper shaft of the tibia, or shinbone. As such, the sartorius is the longest muscle in the human body.
The muscle helps flex, adduct, and rotate the hip. In addition, it helps with the knee's flexion. The femoral artery supplies oxygen-rich blood to the muscle. It is innervated by the femoral nerve as well as the intermediate cutaneous nerve of the thigh.
The sartorius muscle may be susceptible to pes anserine bursitis, which also involves inflammation within the knee's medial (middle) portion. Typically, this condition results from overworking the muscle, and it is an occupational hazard for most athletes. Symptoms often include swelling, tenderness, and pain. Since the muscle covers a range of motion, severe injury such as a tear or rupture can be debilitating.