In human anatomy, the hamstring is a group of tendons contracted by four posterior thigh muscles (posterior femoral muscles, semitendinosus,semimembranosus and biceps femoris) that make up the borders of the space behind the knee, or their corresponding tendons.

In quadrupeds, it is the single large tendon found behind the knee or comparable area.

(Forras: http://en.wikipedia.org/wiki/Hamstring)

Félighártyás izom (m. semimembranosus)

Féliginas izom (m. semitendinosus)

Kétfejű combizom (m. biceps femoris)