Placing the patient supine with arms extended on armboards at greater than 90 degrees may injure which nerve?

• A. Axillary Nerve
• B. Brachial Nerve
• C. Median Nerve
• D. Radial Nerve

Answer: (B)

Excessive abduction of the arm on an armboard places traction/compression on the axillary nerve as it passes through the shoulder region near the surgical neck of the humerus. This nerve travels with the posterior aspect of the shoulder and innervates the deltoid and teres minor, while providing sensation over the lateral shoulder (the “regimental badge” area). When the arm is held extended on an armboard beyond about 90 degrees, the nerve can be stretched or compressed, leading to weakness of shoulder abduction and possible numbness over the lateral shoulder.

That’s why the axillary nerve is the one at risk in this positioning. The other nerves listed are not typically affected by this specific posture: the radial nerve relates more to pressure along the mid-humerus or elbow area, and the median nerve has different positional risks. Also, “brachial nerve” isn’t a standard nerve name—the concern here is specifically the axillary nerve.