The short head of the biceps femoris is the only hamstring not arising from the ischial tuberosity, originating instead from the femoral shaft linea aspera. It is innervated by the peroneal division of the sciatic nerve rather than the tibial division (which supplies the long head and other hamstrings), making it a useful differentiator in sciatic nerve lesion assessment — preserved short head function with long head weakness suggests a proximal sciatic lesion above the peroneal-tibial division.
| Origin | Linea aspera and lateral intermuscular septum of the femur |
|---|---|
| Insertion | Fibular head (combined with the long head) |
| Nerve Supply | Common peroneal nerve (L5, S1, S2) — distinct from the long head which is supplied by the tibial nerve |
| Blood Supply | Perforating arteries of the femoral artery |
| Actions | Knee flexion; External rotation of the flexed knee |
|---|
Because the short head does not cross the hip joint, it is a pure knee flexor and cannot assist in hip extension like the long head. EMG studies show that the short head is predominantly active in the swing phase of gait to decelerate knee extension at terminal swing.
Isolated short head biceps femoris tears from direct impact to the posterior thigh produce lateral knee pain from the fibular head region rather than the typical posterior mid-thigh pain of long head strains. MRI confirms the injury location within the lateral hamstring compartment.
The short head is palpable separately from the long head in the lateral posterior thigh during isolated knee flexion with the hip neutral.
Isolated lateral hamstring injury producing lateral knee and posterior thigh pain, distinguished from long head strain by its location and MRI characterisation.
