Three superficial nerves : superficial peroneal, sural, saphenous
Common peroneal nerve
The common peroneal (lateral popliteal) nerve separates from the tibial nerve (L4-5 and S1-2) and descends along the tendon of the biceps femoris muscle and around the neck of the fibula. Just below the head of the fibula, the common peroneal nerve divides into its terminal branches: the deep peroneal and superficial peroneal nerves. The peroneus longus muscle covers both nerves.
Deep peroneal nerve
The deep peroneal nerve runs downward below the layers of the peroneus longus, extensor digitorum longus, and extensor hallucis longus muscles to the front of the leg. At the ankle level, the nerve lies anterior to the tibia and the interoseeous membrane and close to the anterior tibial artery. It is usually “sandwiched” between the tendons of the anterior tibial and extensor digitorum longus muscles. At this point, the nerve divides into two terminal branches for the foot: the medial and the lateral branches. The medial branch passes over the dorsum of the foot, along the medial side of the dorsalis pedis artery, to the first interosseous space, where it divides into two dorsal digital branches for the nerve supply to the first web space between the big toe and the second toe. The lateral branch of the deep peroneal nerve is directed anterolaterally, penetrates and innervates the extensor digitorum brevis muscle, and terminates as the second, third, and fourth dorsal interosseous nerves. These branches provide the nerve supply to the tarsometatarsal, metatarsophalangeal, and interphalageal joints of the lesser toes.
Superficial peroneal nerve
The superficial peroneal nerve (also called the musculocutanous nerve of the leg) is a branch of the common peroneal nerve. The superficial peroneal nerve gives muscular branches to the peroneus longus and brevis muscles. After piercing the deep fascia covering the muscles, the nerve eventually emerges from the anterolateral compartment of the lower part of the leg and surfaces from beneath the fascia 5-10 cm above the lateral malleolus. At this point, the nerve divides into terminal cutaneous branches: the medial and lateral dorsal cutaneous nerves. These branches carry sensory innervation to the dorsum of the foot and communicate with the saphenous nerve medially, with deep peroneal nerve in the first web space and sural nerve on the lateral aspect of the foot.
The sural nerve is a sensory nerve formed by the union of the medial sural nerve – a branch of the tibial nerve – and lateral sural nerve, a branch of the common peroneal nerve. The sural nerve courses between the heads of the gastrocnemius muscle and after piercing the fascia covering the muscles, emerges on the lateral aspect of the Achilles tendon, 10 to 15 cm above the lateral mallelus. After giving lateral calcaneal branches to the heel, the sural nerve descends 1-1.5 cm behind the lateral malleolus, anterolateral to the short saphenous vein and on the surface of the fascia covering the muscles and tendons. At this level, the nerve supplies the lateral malleolus, Achilles tendon, and the ankle joint. The sural nerve continues on the lateral aspect of the foot supplying innervation to the skin, subcutaneous tissue, fourth interosseous space, and sensory innervation of the fifth toe.
The tibial nerve (medial popliteal or posterior tibial nerve) separates from the common popliteal nerve at various distances from the popliteal fossa crease and joins the tibial artery behind the knee joint. The nerve runs distally in the thick neurovascular fascia and emerges at the inferior third of the leg, from beneath the soleus and gastrocnemius muscles on the medial border of the Achilles tendon. At the level of the medial malleolus, the tibial nerve is covered by the superficial and deep fasciae of the leg. It is positioned laterally and posteriorly to the posterior tibial artery, and midway between the posterior aspect of the medial malleolus and posterior aspect of the Achilles tendon. Just beneath the malleolus, the nerve divides into lateral and medial plantar nerves. The posterior tibial nerve provides cutaneous, articular, and vascular branches to the ankle joint, medial malleolus, inner aspect of the heel, and Achilles tendon. It also carries the branches to the skin, subcutanous tissue, muscles, and bones of the sole.
The saphenous nerve is a terminal cutaneous branch (branches) of the femoral nerve. Its course is in the subcutaneous tissue of the skin on medial aspect of the ankle and foot.