A hamstring is one of three muscles at the back of the thigh - semitendinosus, semimembranosus or biceps femoris - which work to bend the knee.
![semitendinosus](/sites/default/files/users/user1/semitendinosus-03.png)
![semimembranosus](/sites/default/files/users/user1/semimembranosus.png)
![biceps femoris component of the hamstrings muscles](/sites/default/files/users/user1/biceps-femoris.png)
The hamstring used in graft construction
The tendon of semitendinosus is commonly harvested and used in hamstrings grafts for cruciate ligament reconstruction.
Synonyms:
Hamstrings
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