Common Peroneal Nerve

INTRODUCTION:
  • COMMON PERONEAL NERVE /COMMON FIBULAR NERVE: (dorsal divisions of anterior primary rami of L4, L5, S1, S2)
STRUCTURE:
  • The common peroneal nerve, about one-half the size of the tibial nerve, arises 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. Where the common peroneal nerve winds round the head of the fibula, it is palpable.
  • 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 peroneus longus and the bone, and divides beneath the muscle into the superficial peroneal nerve and deep peroneal nerve.
BRANCHES:
  • Previous to its division it gives off articular and lateral sural cutaneous nerves.
  • The articular branches are three in number:
  1. Two of these accompany the superior and inferior lateral genicular arteries to the knee; the upper one occasionally arises from the trunk of the sciatic nerve.
  2. 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 supplies the skin on the posterior and lateral surfaces of the leg.
  • The motor branches:
  1. As the common peroneal nerve exits the popliteal fossa, it courses around the lateral aspect of the leg just below the head of the fibula. Here it is apposed with fibula and gives off two branches, the superficial peroneal branch and deep peroneal branch.
  2. The superficial peroneal nerve supplies the muscles of the lateral compartment of the leg namely: peroneus longus and peroneus brevis. These two muscles assist with eversion and plantar flexion of the foot.
  3. The deep peroneal nerve innervates the muscles of the anterior compartment of the leg which are: tibialis anterior, extensor hallucis longus, extensor digitorum longus, and the peroneus tertius. Together these muscles are responsible for dorsiflexion of the foot and extension of the toes.
  4. The deep peroneal nerve also innervates intrinsic muscles of the foot including the extensor digitorum brevis and the extensor hallucis brevis.
FUNCTIONS
  • The common peroneal nerve innervates the short head of the biceps femoris muscle via a motor branch that exits close to the gluteal cleft. 
  • The remainder of the peroneal-innervated muscles are innervated by its branches, the deep peroneal nerve and superficial peroneal nerve.
  • It provides sensory innervation to the skin over the upper third of the lateral aspect of the leg via the lateral cutaneous nerve of the calf. It gives the peroneal communicating nerve which joins the sural nerve in the midcalf.

Muscular innervation & movement Cutaneous innervation Branches
Extensors of thigh and flexors of legBiceps femoris (short head) Lateral surface of knee Deep Fibular N

  • Dorsi flexes foot (Tibialis anterior & Peroneus tertius )
  • Extends toes (Ext. digitorum brevis & longus, Ext. hallucis longus)
  • Cutaneous innervation of great and second toe
  • The common peroneal nerve is easily injured at the fibular neck.
Exam Question
  • Structures lieing in relation to common peroneal nerve are Head & neck of femur, biceps femoris, lateral head of the gastrocnemius,peroneus longus , head & neck of fibula
  • Nerve that winds around neck of fibula is common peroneal nerve 
  • Muscles of the anterior compartment of the leg which are: tibialis anterior, extensor hallucis longus, extensor digitorum longus, and the peroneus tertius are innervated by deep peroneal 
  • Deep peroneal provides sensory innervations to space between the first and second toe and a small area just proximal to the first and second toe on the plantar aspect of the foot.
  • Muscles of the anterior compartment of the leg are innervated primarily by deep peroneal nerve

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