Saphenous nerve

The saphenous nerve is the largest cutaneous branch of the femoral nerve. This nerve plays a key role in providing sensation to the anteromedial, medial, and posteromedial regions of the lower thigh, leg, and ankle, extending all the way down to the medial malleolus (inner side of the ankle).

Origin and pathway

The saphenous nerve originates in the proximal thigh, as a branch of the posterior (or deeper) division of the femoral nerve. It contains nerve fibers from the L3 and L4 nerve roots. The nerve initially lies lateral to the femoral artery but shifts to a medial position as both proceed through the adductor canal, a passageway in the thigh.

Branches

The saphenous nerve, about the middle of the thigh, gives off a branch which joins the subsartorial plexus of nerves (located underneath the sartorius muscle). At the medial femoral condyle (the inner, lower end of the thigh bone), the saphenous nerve divides into two branches:

• The infrapatellar branch, which moves to the front (anterior) of the knee and provides sensation to the anteroinferior and medial parts of the knee, including the area below the kneecap.

• The sartorial branch, which continues down along the medial knee, passes behind the sartorius muscle, and becomes subcutaneous (between the tendons of sartorius and gracilis muscles). It follows the path of the long saphenous vein, providing sensation to the medial side of the leg and ankle.

Innervation

The saphenous nerve supplies sensation to the skin of the medial, anteromedial, and posteromedial surfaces of the lower thigh, leg, and the medial ankle.