Semitendinosus Muscle

The semitendinosus muscle belongs to the posterior group of muscles of human thigh. It is long and narrow and stretches along the full length of femur, over the semimembranosus muscle. It lies closer to the medial (inner) border of the posterior aspect of thigh, next and parallel to the biceps femoris mucle. Its proximal end is covered by the gluteus maximus muscle.

The semitendinosus muscle arises from the tuberosity of ischium, traveling downwards along the length of thigh, partially covering the semimembranosus muscle. At its distal extremity, it ends up in a long tendon that curves around the medial femoral epicondyle as it runs down slightly beyond the knee-joint. Then the tendon stretches on to the anteromedial surface of tibia to be inserted into its tuberosity.

Action/Function

The semitendinosus muscle flexes the leg at the knee-joint and it also extends the thigh at the hip joint.

Blood supply

It is supplied by the perforating arteries, which are branches arising from the deep artery of thigh, also known as the deep femoral artery.

Innervation

It is innervated by branches springing from the tibial nerve (L4, L6, S1, S2)

Below, diagrammatic picture that shows the thigh posterior side muscles, which include the semitendinosus, semimembranosus, and biceps femoris muscle.

 The superficial aspect of posterior side of side. The semitendinosus muscle can be perceived as it stands out distintively under the skin in athletic humans, such as soccer and football players.