Hamstring muscles: origin, insertion, nerve supply and action
The hamstrings are the muscles of the posterior thigh. Except for the short head of biceps femoris, they arise from the ischial tuberosity, cross both the hip and the knee, extend the hip and flex the knee.
Semitendinosus and semimembranosus lie medially and biceps femoris laterally, which forms the borders of the popliteal fossa.
| Muscle | Origin | Insertion | Innervation | Action |
|---|---|---|---|---|
| Biceps femoris | Long head: ischial tuberosity and sacrotuberous ligament. Short head: lateral lip of the linea aspera. | Head of the fibula, with a slip to the lateral tibial condyle. | Long head: tibial division of the sciatic nerve. Short head: common fibular division (L5-S2). | Flexes the knee and laterally rotates the flexed knee; the long head extends the hip. |
| Semitendinosus | Ischial tuberosity. | Superior part of the medial surface of the tibia (pes anserinus). | Tibial part of the sciatic nerve (L5-S2). | Extends the hip, flexes the knee and medially rotates the flexed knee. |
| Semimembranosus | Superolateral aspect of the ischial tuberosity. | Posterior surface of the medial condyle of the tibia; expansion forms the oblique popliteal ligament. | Tibial part of the sciatic nerve (L5-S2). | Extends the hip, flexes the knee and medially rotates the flexed knee. |
Frequently asked questions
Which nerve supplies the hamstrings?
The tibial division of the sciatic nerve, except the short head of biceps femoris, which is supplied by the common fibular division.
What movements do the hamstrings produce?
Hip extension and knee flexion.
See each muscle in 3D
Last updated September 30, 2026. Educational use only. See our editorial policy.