The saphenous nerve is a sensory branch of the femoral nerve, and supplies sensation to the anteromedial, medial and posteromedial surface of the leg. The nerve passes through the adductor canal, and gives off an infrapatellar branch. It continues to become subcutaneous to supply prepatellar skin and also supplies the medial side of the ankle and foot. In this article we will discuss the anatomy and clinical relevance of the saphenous nerve.
ThighThe saphenous nerve (L3-4) is the largest terminal cutaneous branch of the femoral nerve (dorsal divisions of the ventral rami of L2-L4) that arises within the femoral triangle. The nerve branches from the femoral nerve, and passes lateral to the femoral artery. It then runs deep to the Sartorius muscle, and behind the aponeurotic covering of the adductor canal. At this point the saphenous nerve gives a branch to join the subsartorial plexus. The nerve then descends behind the Sartorius muscle and pierces the fascia lata (it passes between the Sartorius and gracilis muscle), and becomes subcutaneous to supply the skin over the anterior surface of the patella.
The nerve continues to descend down the medial/tibial side of the leg, and runs with the greater saphenous vein. The vein divides into two branches when it reaches the lower third of the leg. A branch of the vein continues to descend down the anterior surface of the tibia, and terminates at the ankle. The other branch passes anterior to the medial malleolus, and drains blood from the medial surface of the foot as far distally as the base of the hallux. 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.
The medial crural cutaneous branches of the saphenous nerve supply sensation to the anterior and medial surface of the leg, as well as 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: 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