Sizing Up the Sartorius Muscle

You may not be familiar with the sartorius muscle, but you’ve no doubt flexed it during countless lower-body exercises, stretches and yoga poses.

The long, bandlike muscle runs down the length of the thigh, starting at the anterior superior iliac spine (ASIS) on the outer edge of the hip and wrapping inward to the medial surface of the tibia behind the knee.

As a two-joint muscle, the sartorius seamlessly serves both the hip and the knee. When acting on the hip joint, it works to flex, abduct and laterally rotate the thigh. At the knee joint, the sartorius helps to flex the leg.

This versatility of movement is what allows you to sit cross-legged and to rotate your leg upward to inspect your heel or rest your foot on your knee (Barclay 2017; Kenhub 2020).

Here are more facts to stitch up your knowledge of the sartorius:

• Its name is derived from the Latin word for “tailor,” since the hip and knee movements it facilitates mimic a tailor sitting cross-legged to work (Barclay 2017).
• The sartorius is the longest muscle in the human body (Barclay 2017).
• In yoga, the sartorius contracts during fire log, a lotus preparation pose involving crossed legs. To lengthen the sartorius, try doing warrior I pose with the back leg straight and the heel up (Keil 2017).
• Young athletes are susceptible to an ASIS avulsion fracture, caused by forceful contraction of the sartorius. Treatment typically involves rest, stretching, use of crutches and range-of-motion exercises (Walters & Varcallo 2018).
• Strengthening exercises for the sartorius include standard squats and lunges, lateral step-ups, lateral band walks, plié squats, and clamshell exercises (Williams 2020).