Intercostal Brachial Nerve

nervus intercostobrachialis

The intercostal brachial nerve is the lateral cutaneous branch of the second intercostal nerve (T2) that crosses the axilla to supply the skin of the inner upper arm and posterior axilla. It is the only cutaneous nerve of the arm that does not arise from the brachial plexus. It communicates with the medial cutaneous nerve of the arm (medial brachial cutaneous) from the medial cord of the brachial plexus.

Region: Chest

Clinical Relevance

Clinical Notes

The intercostal brachial nerve is routinely sacrificed during axillary lymph node dissection for breast cancer, producing numbness and dysaesthesia in the inner upper arm and posterior axilla, a common source of post-mastectomy pain syndrome. Nerve-sparing techniques attempt to preserve the intercostal brachial nerve during sentinel node biopsy and modified radical mastectomy, reducing the incidence of post-operative arm dysaesthesia. When the nerve is divided, the sensory deficit is typically permanent, and patients should be counselled pre-operatively.

Pathology

Common Injuries & Conditions

Post-Mastectomy Pain Syndrome from Intercostal Brachial Nerve Division

Axillary node dissection divides the intercostal brachial nerve producing inner arm numbness, dysaesthesia, and allodynia (post-mastectomy pain syndrome) in 20-60% of patients; nerve-sparing axillary dissection that identifies and preserves the nerve significantly reduces the incidence and severity of this chronic pain condition.