The saphenous nerve (L3, L4) is the largest terminal cutaneous branch of the femoral nerve, and the longest nerve in the body. It arises in the thigh and descends through the adductor canal. It continues its course inferiorly as far as the ankle joint and foot.
Along its course, the saphenous nerve provides the infrapatellar branch and several cutaneous branches. The main function of this nerve is to provide sensory supply to the prepateral skin and the skin of the medial side of the leg and foot.
This article will discuss the anatomy and function of the saphenous nerve.
|Branches||Branch to subsartorial plexus, infrapatellar branch, medial crural branches|
|Supply||Prepatellar skin and skin on the medial side of leg and foot|
- Origin and course
- Branches and innervation
- Clinical relations
Origin and course
The saphenous nerve (L3, L4) arises in the proximal aspect of the anterior thigh from the posterior division of the femoral nerve. It then descends through the femoral triangle, running laterally to the femoral artery. The saphenous nerve then enters the adductor canal, also called Hunter’s canal, where it crosses the femoral artery anteriorly to lie medial to it.
Upon exiting the adductor canal, the nerve then descends behind the sartorius muscle and pierces the fascia lata between the tendons of the sartorius and gracilis muscles and becomes subcutaneous, to supply the skin over the anterior surface of the patella.
The saphenous nerve continues to descend down the medial (tibial) aspect of the leg, running alongside the greater saphenous vein. The nerve communicates with the medial branch of the superficial branch of the common fibular nerve. Both of these nerves then supply sensation to the anterior surface of the leg.
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Branches and innervation
The saphenous nerve gives off several branches at different levels of the lower limb:
- In the middle portion of the thigh, the nerve gives off a branch to the subsartorial plexus.
- Upon exiting the adductor canal at the level of the medial femoral condyle of the femur, the nerve gives off its largest branch, the infrapatellar nerve. This nerve contributes to the peripatellar plexus and innervates the anteroinferior and medial aspects of the knee.
- At the lower third of the leg, the nerve gives off the medial crural cutaneous branches that supply sensation to the anterior and medial surfaces of the leg. These nerves communicate with the cutaneous branches of the obturator and femoral nerve.
Saphenous vein cutdown
A saphenous vein cutdown is a procedure used to gain access to the patient’s venous system. A potential complication of saphenous vein cutdown is damage to the saphenous nerve. Symptoms will include loss of sensation over the medial surface of the leg.
Saphenous nerve block
A saphenous nerve block is used as a supplement to sciatic nerve block during several surgical procedures on the lower limb. Indications for blocking the nerve include trauma to the anteromedial aspect of the knee or leg, as far down as the medial malleolus pain after a partial meniscectomy of the knee manipulation of an ankle fracture, in conjunction with blockage of other nerves which supply sensation to the ankle region.
Saphenous nerve entrapment neuropathy
The adductor canal is a space deep to the sartorius, from the apex of the femoral triangle to the adductor hiatus. The saphenous nerve passes through the adductor (Hunter's) canal along with the femoral artery and vein. The nerve can become entrapped, causing the following symptoms:
- Deep thigh ache
- Knee pain
- Loss of sensation over the medial aspect of the leg
Saphenous nerve: want to learn more about it?
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