Semitendinosus muscle
Muscles of the gluteal and posterior femoral regions. Semitendinosus labeled at bottom left.
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)
Actions	flex knee, extend hip joint
Antagonist	Quadriceps muscle

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

Contents 1 Structure 2 Innervation 3 Actions 4 Additional images 5 See also 6 External links

[edit] 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.

[edit] Innervation

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

[edit] Actions

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

[edit] Additional images

Right hip bone. External surface.

The popliteal, posterior tibial, and peroneal arteries.

Back of left lower extremity.

[edit] See also

• Semimembranosus
• Biceps femoris

[edit] External links

• LUC semt
• SUNY Labs 14:st-0410
• Cross section at UV pembody/body18b
• Anatomy at Dartmouth knee/surface/surface4
• PTCentral

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

v • d • e List of muscles of lower limbs (TA A04.7, GA 4.465) ILIAC Region / ILIOPSOAS psoas major/psoas minor · iliacus BUTTOCKS gluteals: (maximus, medius, minimus) · tensor fasciae latae lateral rotator group: quadratus femoris · inferior gemellus · obturator internus · superior gemellus · piriformis THIGH / compartments Anterior sartorius · quadriceps (rectus femoris, vastus lateralis, vastus intermedius, vastus medialis) · articularis genu Posterior/hamstring biceps femoris · semitendinosus · semimembranosus Medial pectineus · obturator externus · gracilis · adductor (longus, brevis, magnus) Fascia Femoral sheath (Femoral canal) · Femoral ring Adductor canal · Adductor hiatus fascia lata (Iliotibial tract, Lateral intermuscular septum of thigh, Medial intermuscular septum of thigh, Fascia cribrosa/Saphenous opening) LEG/ Crus/ compartments Anterior tibialis anterior · extensor hallucis longus · extensor digitorum longus · peroneus tertius Posterior superficial · triceps surae (gastrocnemius, soleus, Achilles tendon) · plantaris deep · tarsal tunnel (flexor hallucis longus, flexor digitorum longus, tibialis posterior) · popliteus Lateral peroneus muscles (longus, brevis) Fascia Pes anserinus crural fascia (Anterior crural intermuscular septum, Posterior crural intermuscular septum, Transverse intermuscular septum) FOOT Dorsal extensor hallucis brevis · extensor digitorum brevis Plantar 1st layer (abductor hallucis, flexor digitorum brevis, abductor digiti minimi) · 2nd layer (quadratus plantae, lumbrical muscle) · 3rd layer (flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis) · 4th layer (dorsal interossei, plantar interossei) Fascia Plantar fascia retinacula (Peroneal, Inferior extensor, Superior extensor, Flexor)

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