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Medial Brachial Cutaneous Nerve (MBC)

Key Points:
• Examination of this nerve involves testing the skin on the medial aspect of the arm.
Sensory Innervation:
• Provides sensation to the medial cutaneous aspect of the arm.
• Originates from roots C8, T1 and branches from the medial cord.
Nerve Grafting: This nerve is expendable to use as a nerve graft and sensory examination of this nerve will confirm its utility.
Sensory examination includes testing the medial arm sensory territory innervated by the medial brachial cutaneous nerve.
Sensory Examination:
• Ask patients to draw area of diminished sensation/numbness on a body diagram.
• Test the skin along the medial aspect of the arm for reduced/absent sensation by use of light touch or other sensory examination modalities.
Clinical Relevance:
• Provides sensation to the medial arm.
• Can be used as nerve graft material when doing brachial plexus level surgery and the entire proximal brachial plexus is exposed anyways.  Otherwise, this nerve is not typically used as graft material as the medial antebrachial cutaneous nerve is easier to access.
Adjacent Sensory Distribution:
PROXIMAL – Superior lateral cutaneous nerve.
MEDIAL/PROXIMAL – Intercostobrachial nerve.
MEDIAL/DISTAL – Posterior brachial cutaneous nerve.
LATERAL/PROXIMAL – Superior lateral cutaneous nerve.
LATERAL/DISTAL – Lateral antebrachial cutaneous nerve.
DISTAL – Medial antebrachial cutaneous nerve.
Relevant Anatomy:

• Roots: C8, T1.
• Nerve: Medial brachial cutaneous nerve.
• Sensory Territory: Medial aspect of the arm.
• Innervation Route: C8, T1 → medial cord → medial antebrachial cutaneous nerve.
Course: The medial brachial cutaneous nerve comes off of the medial cord or the brachial plexus at a point just proxiamal to where the medial antebrachial cutaneous nerve comes off.  They course through the arm in close proximity to each other.