The Common fibular Nerve (Common Peroneal Nerve;n. peronæus communis; external popliteal nerve; peroneal nerve), about one-half the size of the tibial, is derived from the dorsal branches of the fourth and fifth lumbar and the first and second sacral nerves.

It descends obliquely along the lateral side of the popliteal fossa to the head of the fibula, close to the medial margin of the Biceps femoris muscle. It lies between the tendon of the Biceps femoris and lateral head of the Gastrocnemius muscle, winds around the neck of the fibula, between the Peronæus longus and the bone, and divides beneath the muscle into the superficial and deep peroneal nerves. Previous to its division it gives off articular and lateral sural cutaneous nerves.

The articular branches (rami articulares) are three in number; two of these accompany the superior and inferior lateral genicular arteries to the knee; the upper one occasionallyarises from the trunk of the sciatic nerve. The third (recurrent) articular nerve is given off at the point of division of the common peroneal nerve; it ascends with the anterior recurrent tibial artery through the Tibialis anterior to the front of the knee.

 The lateral sural cutaneous nerve (n. cutaneus suræ lateralis; lateral cutaneous branch) supplies the skin on the posterior and lateral surfaces of the leg; one branch, theperoneal anastomotic (n. communicans fibularis), arises near the head of the fibula, crosses the lateral head of the Gastrocnemius to the middle of the leg, and joins with the medial sural cutaneous to form the sural nerve. The peroneal anastomotic is occasionally continued down as a separate branch as far as the heel.

The Deep Peroneal Nerve (n. peronæus profundus; anterior tibial nerve) begins at the bifurcation of the common peroneal nerve, between the fibula and upper part of the Peronæus longus, passes obliquely forward beneath the Extensor digitorum longus to the front of the interosseous membrane, and comes into relation with the anterior tibial artery above the middle of the leg; it then descends with the artery to the front of the ankle-joint, where it divides into a lateral and a medial terminal branch. It lies at first on the lateral side of the anterior tibial artery, then in front of it, and again on its lateral side at the ankle-joint.

In the leg, the deep peroneal nerve supplies muscular branches to the Tibialis anterior, Extensor digitorum longus, Peronæus tertius, and Extensor hallucis prop ius, and anarticular branch to the ankle-joint.

The lateral terminal branch (external or tarsal branch) passes across the tarsus, beneath the Extensor digitorum brevis, and, having become enlarged like the dorsal interosseous nerve at the wrist, supplies the Extensor digitorumbrevis. From the enlargement three minute interosseous branches are given off, which supply the tarsal joints and the metatarsophalangeal joints of the second, third, and fourth toes. The first of these sends a filament to the second Interosseus dorsalis muscle.

The medial terminal branch (internal branch) accompanies the dorsalis pedis artery along the dorsum of the foot, and, at the first interosseous space, divides into two dorsal digital nerves (nn. digitales dorsales hallucis lateralis et digiti secundi medialis) which supply the adjacent sides of the great and second toes, communicating with the medial dorsal cutaneous branch of the superficial peroneal nerve. Before it divides it gives off to the first space an interosseous branch which supplies the metatarsophalangeal joint of the great toe and sends a filament to the first Interosseous dorsalis muscle.

The Superficial Peroneal Nerve (n. peronæus superficialis; musculocutaneous nerve) supplies the Peronei longus and brevis and the skin over the greater part of the dorsum of the foot. It passes forward between the Peronæi and the Extensor digitorum longus, pierces the deep fascia at the lower third of the leg, and divides into a medial and an intermediate dorsal cutaneous nerve. In its course between the muscles, the nerve gives off muscular branches to the Peronæi longus and brevis, and cutaneous filaments to the integument of the lower part of the leg.

The medial dorsal cutaneous nerve (n. cutaneus dorsalis medialis; internal dorsal cutaneous branch) passes in front of the ankle-joint, and divides into two dorsal digital branches, one of which supplies the medial side of the great toe, the other, the adjacent side of the second and third toes. It also supplies the integument of the medial side of the foot and ankle, and communicates with the saphenous nerve, and with the deep peroneal nerve.

The intermediate dorsal cutaneous nerve (n. cutaneus dorsalis intermedius; external dorsal cutaneous branch), the smaller, passes along the lateral part of the dorsum of the foot, and divides into dorsal digital branches, which supply the contiguous sides of the third and fourth, and of the fourth and fifth toes. It also supplies the skin of the lateral side of the foot and ankle, and communicates with the sural nerve.The branches of the superficial peroneal nerve supply the skin of the dorsal surfaces of all the toes excepting the lateral side of the little toe, and the adjoining sides of the great and second toes, the former being supplied by the lateral dorsal cutaneous nerve from the sural nerve, and the latter by the medial branch of the deep peroneal nerve. Frequently some of the lateral branches of the superficial peroneal are absent, and their places are then taken by branches of the sural nerve.


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