The sartorius (also sartorius muscle, latin: musculus sartorius) is the longest muscle of the thigh. The sartorius is a superficial and thin muscle located in the anterior region of the thigh.
The sartorius originates from the anterior superior iliac spine. The sartorius passes inferomedially across the anterior part of the thigh. Tendons of the sartorius, gracilis and semitendinosus muscles form a common plate - pes anserinus that inserts onto the tibial tuberosity.
The main function of the sartorius is flexion and external rotation of the femur, flexion and internal rotation of the knee.