The sartorius muscle is a long, thin muscle located in the anterior region of the thigh. It originates at the anterior superior iliac spine of the pelvis and inserts into the medial aspect of the tibial tuberosity of the tibia (shin bone). The sartorius muscle is the longest muscle in the human body, and is one of the muscles that make up the lateral compartment of the thigh.

The main function of the sartorius muscle is to flex and rotate the knee and hip joints. This movement is essential for activities such as crossing the legs, and helps to provide stability and support for the lower limb. The sartorius muscle also helps to abduct (move away from the midline of the body) the thigh, and assist in flexion of the hip joint, such as standing on one foot or stepping over an obstacle.