The semimembranosus is a muscle within the posterior compartment of the thigh. It is located deep to the semitendinosus muscle within the medial aspect of the posterior thigh. Attachments: Originates from the ischial tuberosity (more superiorly than the origin of the semitendinosus and biceps femoris). Attaches to the medial tibial condyle. Actions: Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint. Innervation: Tibial part of the sciatic nerve. Blood Supply: Profunda femoris artery. By TeachMeSeries Ltd (2025) Fig 1The muscles of the posterior thigh. By TeachMeSeries Ltd (2025) Fig 2Cross section of the thigh, showing the position of the major muscle groups. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Print Article Rate This Article