Biceps Femoris Muscle (Left)

Origin

The biceps femoris muscle consists of two heads:

- a long head, which originates from the medial aspect of the posterior portion of the ischial tuberosity;

- a short head, which originates from the lateral lip of linea aspera and lateral supracondylar line of the femur.

Insertion

The fibers of the long and short heads of biceps femoris travel inferiorly and converge to a single biceps femoris tendon. This tendon splits around the fibular collateral ligament and then inserts onto the lateral aspect of the head of the fibula.

Key Features & Anatomical Relations

Overall, the biceps femoris muscle is found in the posterior compartment of the thigh. It is a fusiform type of skeletal muscle and is composed of a medially located long head and a laterally located short head.

The biceps femoris muscle is located:

- anterior to the gluteus maximus muscle (at its proximal end);

- posterior to the femur, adductor magnus and vastus lateralis muscles, and the sciatic nerve;

- medial to the iliotibial tract;

- lateral to the semitendinosus and semimembranosus muscles.

Overall, the biceps femoris muscle contributes to the formation of the popliteal fossa, where the muscle and tendon form its superolateral boundary. The term “hamstrings” is the collective name given to the long head of biceps femoris, semitendinosus, and semimembranosus muscles. These three muscles share similar features, including:

- originating from the ischial tuberosity;

- acting on both the hip and knee joints;

- innervated by the tibial division of sciatic nerve.

Actions & Testing

Overall, the biceps femoris is involved in multiple actions:

- flexes the leg at the knee joint;

- laterally rotates the leg at the knee joint while this joint is held in a semiflexed position;

- extends the thigh at the hip joint.

The biceps femoris muscle cannot be tested in isolation, therefore all of the muscles of the posterior compartment of the thigh are tested simultaneously by flexing the leg at the knee joint against resistance while lying in the prone position, during which the biceps femoris tendon can be seen and palpated (Standring, 2016).

List of Clinical Correlates

- Hamstring strain

- Hamstring tear

- Avulsion of ischial tuberosity

- Biceps femoris tendinitis

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.