Biceps Femoris

Musculus biceps femoris

Lower Body Lower BodyLegsHamstringsPosterior ChainHinge

The biceps femoris is the lateral hamstring, with a long head that crosses both the hip and knee and a short head that crosses only the knee. Functionally it flexes the knee, extends the hip (long head), and externally rotates the flexed knee. For lifters it is the most injury-prone hamstring during sprinting and stiff-leg deadlifts, so balancing hip-dominant work (RDLs, good mornings) with knee-flexion work (leg curls) is key to resilience.

Actions

Knee flexion, Hip extension, Lateral rotation of the leg at the knee (when knee flexed)

Origin

Long head: ischial tuberosity (via the conjoint tendon, shared with semitendinosus) and sacrotuberous ligament. Short head: lateral lip of the linea aspera of the femur.

Insertion

Head of the fibula, with a secondary slip to the lateral condyle of the tibia

Innervation

Long head: tibial division of the sciatic nerve (L5-S2). Short head: common fibular (peroneal) division of the sciatic nerve (L5-S2)

Blood supply

Perforating branches of the profunda femoris (deep femoral) artery, inferior gluteal artery, and popliteal artery

Heads

Long head, Short head

Wikipedia ↗

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