Hamstring Group

Joe Muscolino

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Superficial and deep views of the posterior thigh demonstrating the hamstring group of muscles: semitendinosus, semimembranosus, and biceps femoris (long head and short head).

There are three hamstring muscles / four hamstring muscle heads:

  • Semitendinosus (medial side, superficial)
  • Semimembranosus (medial side, deep)
  • Biceps femoris
    • long head (lateral side, superficial)
    • short head (lateral side, deep)


  • The biceps femoris attaches from the ischial tuberosity (long head) and linea aspera of the femur (short head) to the head of the fibula.
  • The semitendinosus attaches from the ischial tuberosity to the pes anserine tendon at the proximal anteromedial tibia.
  • The semimembranosus attaches from the ischial tuberosity to the posterior surface of the medial condyle of the tibia.



  • As a group, the hamstrings extend the thigh and posteriorly tilt the pelvis at the hip joint.
  • They also flex the leg (and/or thigh) at the knee joint.
  • (Note: The short head of the biceps femoris does not cross the hip joint and therefore has no action at that joint.)