The Sartorius muscle is a long thin muscle that runs down diagonally the length of the thigh. It is the longest muscle in the human body. Its upper portion forms the lateral border of the femoral triangle. The sartorius muscle originates from tendinous fibers from the anterior superior iliac spine, running obliquely across the upper and anterior part of the thigh in an inferomedial direction, descending as far as the medial side of the knee and passing behind the medial condyle of the femur to end in a tendon.
The Sartorius muscle is innervated by the femoral nerve. It flexes, abducts, and laterally rotates thigh and hip.