Which muscle does the common peroneal nerve run beneath?

The common peroneal nerve, which is a branch of the sciatic nerve, runs beneath the biceps femoris muscle as it courses around the posterior aspect of the knee. The biceps femoris, part of the hamstring muscle group, originates from the ischial tuberosity (long head) and the linea aspera of the femur (short head), and it contributes to knee flexion and lateral rotation of the leg.

As the common peroneal nerve ascends laterally from the sciatic nerve, it wraps around the neck of the fibula, making it particularly vulnerable to injury in this location. Understanding the anatomical relationship between the nerve and the biceps femoris is crucial for surgical procedures around the knee and for diagnosing conditions related to nerve injuries.

The other muscles listed do not have the common peroneal nerve running beneath them. The semitendinosus and the rectus femoris are situated more medially or anteriorly, while the sartorius is located anteriorly and laterally, far from the trajectory of the common peroneal nerve as it passes near the biceps femoris.