The biceps femoris is a muscle located in the posterior compartment of the thigh. It is the most lateral muscle within this compartment, consisting of two heads: the long head, which originates from the ischial tuberosity of the pelvis, and the short head which originates from the linea aspera on the posterior surface of the femur. These two heads form a common tendon which can be palpated laterally in the popliteal fossa of the knee region. This tendon attaches onto the head of the fibula.
The biceps femoris works to strongly flex the knee joint as well as to weakly extend and laterally rotate the thigh. The long head is innervated by the tibial part of the sciatic nerve, while the short head is innervated by the common fibular part of the sciatic nerve. The artery that supplies blood to the muscle is the profunda femoris artery.
Due to its placement and attachments, the biceps femoris muscle is considered a powerful flexor of the knee joint as well as a weak extensor and lateral rotator of the thigh. This action is used frequently in everyday life during activities such as walking, running, and jumping. It is also used intensively during activities such as sprinting, ballet dancing, and football. During sprinting and football, this muscle assists in rapid knee bending and foot plantarflexion. In addition, during ballet dancing, it assists in the rapid knee extension and plantar flexion that is characteristic of this dance form.
Injury to the biceps femoris can occur due to muscle strain, tears, or overuse. Common symptoms of injury may include pain, swelling, bruising, and limited range of motion. Treatment of an injured biceps femoris muscle usually involves rest, icing, and physical therapy. Exercises may include isometric strengthening, stretching, and rehabilitation exercises to restore normal range of motion and strength. More severe injuries may require immobilization or surgery.
The biceps femoris is an important muscle in the posterior compartment of the thigh. It is crucial for activities such as walking, running, and jumping and is used intensely in sprinting, football, and ballet dancing. Its attachments allow it to be a powerful knee flexor as well as a weak thigh extensor and lateral rotator. Injury to the biceps femoris can occur with muscle strain, tears, or overuse and may require rest, icing, and physical therapy. In more severe cases, surgery may be necessary.
