Which muscles are primarily affected by axillary nerve denervation?

The muscles primarily affected by axillary nerve denervation are the deltoid and teres minor. The axillary nerve innervates the deltoid muscle, which is crucial for shoulder abduction, particularly when the arm is elevated, as well as contributing to shoulder flexion and extension. The teres minor, which is part of the rotator cuff, aids in the lateral rotation of the shoulder.

When the axillary nerve is compromised due to an injury or a surgical complication, the primary clinical manifestations include weakness in shoulder abduction and a rounded shoulder appearance. This is because the deltoid is no longer functioning properly, which significantly impacts the arm's ability to be raised away from the body. Additionally, the teres minor plays a vital role in stabilizing the shoulder joint, and its denervation can lead to further instability and dysfunction.

The other muscle groups listed are not primarily innervated by the axillary nerve and, therefore, would not be primarily affected by its denervation. Understanding the anatomy and nerve supply is key to diagnosing and managing shoulder injuries and conditions related to nerve impairment.