Corpus: Axillary nerve

The axillary nerve is a mixed nerve that originates from the posterior cord of the brachial plexus. It contains fibres from the C5 and C6 segments of the spinal cord.

The nerve passes around the surgical neck of humerus near the joint capsule together with he posterior circumflex humeral artery and vein. It then crosses the lateral axillary gap, which is bordered laterally by the humerus and by the long head of the triceps brachii muscle. It continues through the teres major muscle and reaches under the deltoid muscle. Before passing through the axillary gap, it releases its sensory terminal branch, the superior lateral brachial cutaneous nerve, which penetrates the fascia and radiates into the subcutaneous tissue of the lateral shoulder.

3.1. Motor innervation

The axillary nerve innervates the following shoulder muscles motorically:

• deltoid muscle
• teres minor muscle

3.2. Sensitive innervation

Its sensory terminal branch supplies the skin of the lateral shoulder region.

Traumatic damage to the nerve, for example, by compression, leads to axillary nerve syndrome.