Endoneurium

The innermost connective-tissue layer of a peripheral nerve, enclosing each axon and its Schwann cells within the fascicle bounded by the perineurium. The endoneurial tube guides regenerating axons back to their original targets; its preservation distinguishes a second-degree (fully recovering) injury from a third-degree one.

Related terms

• Glossary

  Sunderland classification

  Sunderland's 1951 five-degree classification of nerve injury by the connective-tissue layer lost: first degree (neurapraxia), second (axon only, endoneurium intact — full recovery), third (endoneurium disrupted — partial recovery), fourth (perineurium disrupted — usually needs surgery) and fifth (complete transection). Mackinnon and Dellon added a sixth degree for mixed injuries.

• Anatomy

  Bands of Büngner

  Longitudinal columns of proliferating Schwann cells that fill the empty endoneurial tubes of the distal nerve stump after Wallerian degeneration and guide regenerating axons back towards their targets. Their growth-supportive state is time-limited, which is one reason delayed repair does badly.

Articles mentioning this term

1. FESSH preparation · 26 September 2026

   Peripheral nerve injury and repair

   Peripheral nerve injury for FESSH candidates: degeneration, Seddon and Sunderland grades, electrodiagnosis, timing, grafts, conduits and nerve transfers.

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