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.)