Axillary nerve receives contributions from which nerve roots?

Axillary nerve receives contributions from which nerve roots?

• A. C8-T1
• B. C7-C8
• C. C5-C7
• D. C5-C6

Answer: (D)

The axillary nerve carries fibers from the upper root level of the brachial plexus, specifically C5 and C6, because it arises from the posterior cord formed by those roots. This pairing matches the nerve’s functions: it innervates the deltoid and teres minor, which enable shoulder abduction and lateral rotation, and it provides sensation over the lateral shoulder—areas primarily served by input from C5–C6. While some texts note occasional input from other levels, the standard and most consistent contributor is C5–C6. Roots lower than that (such as C8–T1) or higher combinations that include C7 generally relate to other nerves, not the axillary nerve.

The axillary nerve carries fibers from the upper root level of the brachial plexus, specifically C5 and C6, because it arises from the posterior cord formed by those roots. This pairing matches the nerve’s functions: it innervates the deltoid and teres minor, which enable shoulder abduction and lateral rotation, and it provides sensation over the lateral shoulder—areas primarily served by input from C5–C6. While some texts note occasional input from other levels, the standard and most consistent contributor is C5–C6. Roots lower than that (such as C8–T1) or higher combinations that include C7 generally relate to other nerves, not the axillary nerve.