Axillary nerve dysfunction is a general term that refers to any type of dysfunction of the axillary nerve

Axillary nerve

The axillary nerve or the circumflex nerve is a nerve of the human body, that comes off the of the brachial plexus at the level of the axilla and carries nerve fibers from C5 and C6...

. The axillary nerve is a branch of the brachial plexus

Brachial plexus

The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...

 that innervates the deltoid

Deltoid muscle

In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder. Anatomically, it appears to be made up of three distinct sets of fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central...

 and teres minor muscle

Teres minor muscle

The teres minor is a narrow, elongated muscle of the rotator cuff.-Origin:It arises from the dorsal surface of the axillary border of the scapula for the upper two-thirds of its extent, and from two aponeurotic laminæ, one of which separates it from the infraspinatus muscle, the other from the...

s. This nerve can be injured or damaged in a variety of ways - penetrating injury such as knife or gunshot wounds, surgical trauma, stretch injury (common after motor cycle accidents), and various metabolic or rheumatic conditions that may cause focal disruption of the blood supply to the nerve. The exact cause of the axillary nerve dusfunction cannot be identified with electromyography

Electromyography

Electromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...

, but the way that the nerve has responded to the injury, and whether or not the nerve is healing, can.