Hamstring

hamstring, any of the three muscles at the back of the thigh that begin at the pelvis (specifically originating on the ischial tuberosity) and attach below the knee or to their associated tendons. These muscles serve to flex and rotate the leg and extend the thigh. Injuries to the hamstrings are among the most common sports injuries.

The word hamstring comes from the Old English hamm, “hollow or bend of the knee,” and string, referring to a ligament or tendon. Many medical sources use hamstring to refer primarily to the two groups of tendons at the back of the knee where the hamstring muscles insert onto the tibia and fibula bones of the lower leg. However, in colloquial settings, it is perhaps more common to encounter the term hamstring being used to refer to the muscles, which are more likely to be directly exercised or injured.