skeletal muscle weight semimembranosus muscle weight 2013-01-14T11:34:23Z CMO:0001396 JSmith The weight or the measure of the heaviness of the semimembranosus muscle, one of three posterior femoral muscles. Situated at the back and medial side of the thigh, it originates in a thick tendon attached to the tuberosity of the ischium and inserts into the horizontal groove on the medial condyle of the tibia. It functions to flex the leg, to rotate it medially after flexion, and to extend the thigh. clinical_measurement_ontology