The lateral cutaneous nerve of the forearm is the terminal sensory branch of the musculocutaneous nerve (C5-C6), emerging from the lateral border of the biceps tendon at the elbow to supply cutaneous sensation to the lateral forearm from the elbow to the base of the thenar eminence. It divides into anterior and posterior branches, the anterior branch being larger and supplying the anterior lateral forearm, and the posterior branch supplying the posterior lateral forearm.
This nerve is the most commonly injured forearm nerve during antecubital venepuncture, particularly when the needle is placed too laterally near the biceps tendon margin. It is also at risk during distal biceps tendon repair via the anterior approach. The nerve is an important target for nerve blocks to provide lateral forearm analgesia for arteriovenous fistula creation at the wrist. It is the most consistent donor nerve for sensory reinnervation of the hand in complex nerve reconstruction.
Inadvertent needle injury at the lateral antecubital fossa produces lateral forearm numbness or burning dysaesthesia that can persist for weeks to months, managed conservatively with reassurance, although a painful neuroma occasionally requires desensitisation therapy or surgical excision.
The lateral cutaneous nerve of the forearm is at risk during the anterior approach for distal biceps reattachment, where retraction or direct injury produces lateral forearm sensory loss, a recognised complication reported in up to 10% of cases.
