The biceps femoris has two distinct heads with different nerve supplies (tibial vs common peroneal), making it a key muscle for EMG localisation of sciatic nerve injuries. Its common tendon at the fibular head is the primary lateral knee static stabiliser.
| Origin | Long head: ischial tuberosity — inferior facet (with semitendinosus); Short head: lateral lip of the linea aspera and lateral supracondylar line |
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| Insertion | Head of the fibula — both heads combine into the common biceps tendon |
| Nerve Supply | Long head: tibial nerve (L5, S1, S2); Short head: common peroneal nerve (L5, S1, S2) |
| Blood Supply | Perforating branches of the profunda femoris |
| Actions | Flexes the knee; Extends the hip (long head); Laterally rotates the tibia when the knee is flexed; The primary lateral rotator of the flexed knee |
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The biceps femoris tendon avulsion from the fibular head is a component of the posterolateral corner (PLC) injury. The fabellofibular ligament and arcuate ligament attach near the biceps insertion. In PLC reconstruction, the biceps femoris tendon is used as a reconstructive anchor for the lateral ligamentous complex.
Palpated on the lateral posterior thigh as the dominant lateral hamstring during resisted knee flexion in external rotation.
Avulsion of the common biceps tendon from the fibular head as part of posterolateral corner disruption, producing lateral knee instability and dial test positive, requiring PLC reconstruction.
