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Medial Cutaneous Nerve of the Arm (Detail)

nervus cutaneus brachii medialis (aspectus detailiatus)

The medial cutaneous nerve of the arm (medial brachial cutaneous nerve) arises from the medial cord of the brachial plexus (C8, T1) and supplies the medial skin of the upper arm from the axilla to the medial elbow. It communicates with the intercostobrachial nerve (T2) in the axilla, forming the intercostobrachial-medial cutaneous complex that supplies the medial and posterior upper arm.

Region: Upper Arm

Clinical Relevance

Clinical Notes

The medial brachial cutaneous nerve is sacrificed in axillary lymph node dissection for breast cancer, producing medial upper arm numbness and the characteristic post-mastectomy pain syndrome. Its sensory territory overlaps significantly with the intercostobrachial nerve, so the functional deficit of each in isolation is variable. Neuroma formation after division during axillary dissection is a source of chronic post-surgical pain. Its C8-T1 origin means it is affected in lower trunk brachial plexus injuries (Klumpke palsy).

Pathology

Common Injuries & Conditions

Post-Mastectomy Medial Arm Numbness

Sensory loss over the medial upper arm from medial brachial cutaneous nerve sacrifice during axillary dissection, producing a patch of numbness that may develop into post-mastectomy pain syndrome with allodynia.