The hamstrings
The hamstrings are three muscles on the back of the thigh. The semitendinosus and the semimembranosus run down the inner side to the tibia, the biceps femoris down the outer side to the head of the fibula. Their tendons can be felt as cords on both sides of the back of the bent knee.
Muscles of the buttock and the back of the thigh, with the gluteus maximus and medius cut to show the deep muscles beneath, and the hamstrings below, Gray's Anatomy, 1918, figure 434Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray434.png)
All three start on the ischial tuberosity, the bone a person sits on, apart from the short head of the biceps, which starts on the femur. They cross both the hip and the knee, so they straighten the hip and bend the knee. In walking they slow the swinging leg just before the heel strikes the ground.
Muscles of the hip and thigh from the front and from behind, among them the quadriceps, the sartorius, the adductors and the hamstrings, OpenStax Anatomy and PhysiologyWikimedia Commons, OpenStax, CC BY 4.0 (1122 Gluteal Muscles that Move the Femur.jpg)
Sprinters often strain a hamstring at the moment the muscle is stretched while it contracts hard. All three are supplied by the sciatic nerve. The name joins ham, an old word for the back of the thigh and knee, with string, for the tendons.
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), chapter on the pelvic girdle, gluteal region and thigh.
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