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.