Which cutaneous nerve crosses the axilla transversely?

• A. Medial brachial cutaneous nerve
• B. Intercostobrachial nerve
• C. Lateral brachial cutaneous nerve
• D. Thoracodorsal nerve

Answer: (B)

The intercostobrachial nerve is the correct answer because it is a branch of the second intercostal nerve that supplies the skin of the upper medial arm and crosses the axilla transversely. This nerve is responsible for providing sensory innervation to the skin in that area, making it crucial for tactile sensation.

In contrast, the medial brachial cutaneous nerve primarily supplies sensation to the skin of the medial side of the arm, but it does not cross the axilla transversely. The lateral brachial cutaneous nerve branches from the axillary nerve and supplies the skin over the deltoid muscle and lateral aspect of the arm, so it is oriented differently and also does not cross the axilla. The thoracodorsal nerve innervates the latissimus dorsi muscle and does not have a cutaneous distribution; hence, it does not serve the skin in the area of interest.

Thus, the specific transverse crossing of the intercostobrachial nerve across the axilla distinguishes it as the correct response.