axillary nerve palsy/impairment leads to difficulty performing the actions of the muscles it innervates. Those muscles are the deltoid and teres minor. The teres minor externally rotates. When the teres minor nerve (axillary) is impaired it therefore leads to difficulty externally rotating, and a slightly interally rotated humerus when at rest.
Amboss> peripheral nerve injuries> Brachial plexus injuries>Peripheral nerve injuries in the upper extremity> [table] Overview of peripheral nerve injuries in the upper extremity > [row] axillary nerve injury
Source: AMBOSS - https://next.amboss.com/us/article/Zi0ZJf?q=axillary%20nerve%20palsy#Zda725ab7a5a027b7fdcc6d35df14ba67
lower scapular nerve innervates teres mj and subscapularis. not teres mn