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Muscles of the Hip Joint: Origin, Insertion, Action

Terms in this set (22)

Semitendinosus, as its name suggests, has a long tendon.

Proximal Attachment
Semitendinosus arises from the supero-medial part of the ischial tuberosity of the hip bone, in common with the tendon of origin of the long head of the biceps femoris muscle. From this origin, the semitendinosus muscle runs obliquely, infero-medially behind semimembranosus. Approximately halfway down the thigh, the semitendinosus muscle gives rise to a strong, rounded tendon.

Distal Attachment
In the lower part of the thigh, semitendinosus and semimembranosus together form the upper medial boundary of the popliteal fossa. Distally, semitendinosus is attached to the upper part of the medial surface of the tibial shaft postero-inferior to the insertion of sartorius and gracilis.

Pes anserinus is a commonly used expression (though not one that is officially recognized in anatomical nomenclature) for the partly joined flattened tendons of the insertion of sartorius, gracilis and semitendinosus. These tendons are inserted onto the medial surface of the upper part of the tibia. The fancied resemblance of this arrangement to a goose's foot is the reason for the name! Within this arrangement, the tendons of gracilis and semitendinosus are relatively thick, strong and cord-like, whereas the sartorius tendon is almost fascial in its appearance.

Nerve Supply
Semitendinosus is innervated by the tibial component of the sciatic nerve, derived from L5, S1 and 2.

Action
As it is a hamstring muscle, its action is to assist in flexion of the knee and extension of the hip joint. It also medially rotates the hip joint when the hip is extended and medially rotates the lower leg when the knee is semi-flexed.
Semimembranosus is a muscle of the posterior (hamstring) compartment of the thigh, and occupies the postero-medial part of the thigh. Semimembranosus arises from a strong membranous tendon, which gives the muscle its name.

Proximal Attachment
Proximally, semimembranosus arises from the supero-lateral aspect of the ischial tuberosity by a long and flattened tendon. The tendon arises from the upper lateral facet of the ischial tuberosity and continues along the lateral margin of the muscle. The fleshy muscle belly lies medial and deep to the tendon and muscle of semitendinosus and the long head of biceps femoris muscles.

Distal Attachment
It passes downwards and medially, with the semitendinosus tendon grooving its superficial surface. It ends at the back of the knee at a tendon, which inserts into the horizontal groove at the posterior medial corner of the medial tibial condyle. Semimembranosus is attached principally to the posterior surface of the medial tibial condyle. From this insertion several expansions from the tendon pass in different directions. One of the expansions (oblique popliteal ligament) runs supero-laterally behind the knee joint reinforcing the joint capsule. Another prominent expansion passes downwards and laterally to cover the popliteus muscle. This is called the 'popliteus fascia'. A further expansion runs antero-medially along the medial aspect of the knee and partially blends with the capsule of the knee joint.

Nerve Supply
Semimembranosus is innervated by the tibial component of the sciatic nerve, derived from L5, S1 and 2.

Action
In common with the other hamstring muscles, the action of semimembranosus is to flex the knee joint and to assist in extending the hip joint. It also medially rotates the hip joint when the hip is extended and medially rotates the lower leg when the knee is semi-flexed.