Question #440

Semimembranosus is one of the hamstring group of muscles in the posterior compartment of the thigh. It arises from the posterolateral aspect of the ischial tuberosity before being crossed by the long head of biceps femoris. It is a long flat muscle with semitendinosus lying in a groove on its surface.

It passes medially to insert into a groove on the medial tibial condyle. In addition it also has fibres that extend posteriorly.

It is innervated by the tibial branch of the sciatic nerve.

As a hamstring muscle it flexes the knee and extends the hip. In addition, depending on the position of these joints, it can both medially rotate the thigh and the tibia.

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