Deep fibular (peroneal) nerve (L4–S1)

Terminal branches · L4 L5 S1

Pierces the anterior intermuscular septum to run down the anterior compartment on the interosseous membrane with the anterior tibial artery, passes under the extensor retinaculum and ends on the dorsum of the foot.

Traced from the start

  1. L4 anterior ramusL5 anterior ramus
  2. S1 anterior ramusS2 anterior ramusS3 anterior ramusS4 anterior ramus
  3. Lumbosacral trunk (L4–L5)Sacral plexus anterior divisionsSacral plexus posterior divisions
  4. Sciatic nerve (L4–S3)
  5. Common fibular (peroneal) nerve (L4–S2)
  6. Deep fibular (peroneal) nerve (L4–S1)

Detail

Motor
Tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius; extensor digitorum brevis in the foot
Sensory
First web space (between the great and second toes) only
Companion
Anterior tibial artery, continuing as dorsalis pedis

When it goes wrong

Anterior compartment syndrome after a tibial fracture or unaccustomed exertion

Pain out of proportion, worse on passive toe flexion (stretching the compartment); numbness of the first web space is the EARLIEST nerve sign, followed by weak dorsiflexion; pulses persist until late — needs urgent fasciotomy

Anterior tarsal tunnel syndrome: tight footwear compressing the nerve under the extensor retinaculum

Numb first web space with wasting of extensor digitorum brevis, dorsiflexion preserved

Practise this structure

1 question in the bank tagged Deep Fibular Nerve.