Posterior view of left lower extremity.
Origintuberosity of the ischium, linea aspera
Insertiontibia, fibula
Arteryinferior gluteal artery, profunda femoris artery
Nervesciatic nerve (tibial nerve and common fibular nerve)[1][2]
Actionsflexion of knee, extension of hip
AntagonistRectus femoris muscle
Anatomical terms of muscle

In human anatomy, a hamstring is one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris).[3] The hamstrings are quite susceptible to injury.

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


The common criteria of any hamstring muscles are:

  1. Muscles should originate from ischial tuberosity.
  2. Muscles should be inserted over the knee joint, in the tibia or in the fibula.
  3. Muscles will be innervated by the tibial branch of the sciatic nerve.
  4. Muscle will participate in flexion of the knee joint and extension of the hip joint.

Those muscle which fulfills all of the four criteria are called true hamstrings.
The adductor magnus reaches only up to the adductor tubercle of the femur, but it is included amongst the hamstrings because the tibial collateral ligament of the knee joint morphologically is the degenerated tendon of this muscle. The ligament is attached to medial epicondyle, two millimeters from the adductor tubercle.