The femoral nerve (also called the anterior crural nerve) is the largest nerve of the lumbar plexus. It arises from the ventral rami of the second, third and fourth lumbar nerves (L2 - L4). The femoral nerve is a mixed nerve containing motor and sensory fibers.

At first, the femoral nerve lies in the groove between the psoas major and iliacus. It leaves the pelvic cavity via the muscular lacuna (an anatomical structure in the lateral compartment of the thigh below the inguinal ligament). Further, the nerve descends along the medial border of the thigh and continues as the saphenous nerve.

On its course, the femoral nerve also gives off small branches to the hip joint, to the quadriceps femoris, sartorius and pectineus, and anterior cutaneous branches to the skin of the thigh.

Saphenous nerve

The saphenous nerve (also known as the long saphenous nerve, internal saphenous nerve) is a large cutaneous branch of the femoral nerve, which contains only sensory fibers.

This nerve runs posteriorly to the sartorius muscle, enters the adductor canal (a channel in the middle third of the thigh) and pierces the anterior wall of the channel. 

After emerging from the adductor canal, the saphenous nerve curves around the medial condyle of the femur, reaching the medial side of the lower leg. Then the nerve continues downward, crosses the medial malleolus and terminates at the medial edge of the foot.

The saphenous nerve innervates skin in the medial region of the lower leg and in the medial edge of the foot.