What is the primary function of the muscles innervated by the femoral nerve?

The primary function of the muscles innervated by the femoral nerve is indeed the extension of the knee. The femoral nerve primarily supplies the quadriceps muscle group, which is the main extensor of the knee joint. This muscle group is essential for activities such as walking, running, and standing up from a sitting position, as it is responsible for straightening the knee.

In contrast, while flexion of the knee is a necessary movement, it is primarily accomplished by muscles innervated by the sciatic nerve, such as the hamstrings. Abduction of the hip is mainly performed by muscles innervated by the superior gluteal nerve, and adduction of the thigh is conducted by the adductor muscles, which receive innervation from the obturator nerve among others. Thus, the focus on knee extension for the femoral nerve highlights its critical role in lower limb movement.