semimembranosus

sem·i·mem·bra·no·sus (sm-mmbr-nss, sm-)

n.

A muscle with origin from the tuberosity of the ischium, with insertion into the medial condyle of the tibia and by membrane to the tibial collateral ligament of the knee joint, the popliteal fascia, and the lateral condyle of the femur, with nerve supply from the tibial nerve, and whose action flexes the leg, rotates it medially, and makes the capsule of the knee joint tense.