Semitendinosus muscle

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Semitendinosus muscle
Muscles of the gluteal and posterior femoral regions. Semitendinosus labeled at bottom left.
Gray432.png
Semitendinosus visible at bottom left.
Latin musculus semitendinosus
Gray's subject #128 479
Origin: tuberosity of the ischium
Insertion: pes anserinus
Artery: inferior gluteal artery, perforating arteries
Nerve: sciatic (tibial, L5, S1, S2)
Action: flex knee, extend hip joint
Antagonist: Quadriceps muscle
Dorlands/Elsevier m_22/12550732

The semitendinosus is a muscle in the back of the thigh; it is one of the hamstrings.

Structure

The semitendinosus, remarkable for the great length of its tendon of insertion, is situated at the posterior and medial aspect of the thigh.

It arises from the lower and medial impression on the tuberosity of the ischium, by a tendon common to it and the long head of the biceps femoris; it also arises from an aponeurosis which connects the adjacent surfaces of the two muscles to the extent of about 7.5 cm. from their origin.

The muscle is fusiform and ends a little below the middle of the thigh in a long round tendon which lies along the medial side of the popliteal fossa; it then curves around the medial condyle of the tibia and passes over the tibial collateral ligament of the knee-joint, from which it is separated by a bursa, and is inserted into the upper part of the medial surface of the body of the tibia, nearly as far forward as its anterior crest.

At its insertion it gives off from its lower border a prolongation to the deep fascia of the leg and lies behind the tendon of the sartorius, and below that of the gracilis, to which it is united. These three tendons form what is known as the pes anserinus, so named because it looks like the foot of a goose.

A tendinous intersection is usually observed about the middle of the muscle.

Innervation

The semitendinosus is innervated by the tibial part of the sciatic nerve.

Actions

The semitendinosus helps to extend (straighten) the hip joint and flex (bend) the knee joint. It also helps medially rotate the knee.

Additional images

See also

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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