If the axillary nerve was damaged, which muscle would likely be affected?

The deltoid muscle would likely be affected if the axillary nerve was damaged because this nerve innervates the deltoid, which is responsible for shoulder abduction, flexion, and extension. Damage to the axillary nerve can result from shoulder dislocations or fractures of the surgical neck of the humerus, which can lead to weakness or paralysis of the deltoid muscle.

The supraspinatus and infraspinatus muscles are primarily innervated by the suprascapular nerve, so they would be less directly affected by damage to the axillary nerve. The teres major muscle is innervated by the lower subscapular nerve, meaning its function would not be as compromised by axillary nerve damage. Therefore, the most directly impacted muscle by injury to the axillary nerve is the deltoid.