AXILLARY NERVE

SUMMARY

ORIGIN
1. Branch of the posterior cord of the brachial plexus - C5, C6.

COURSE
2. Passes out of the axilla, through the quadrangular space with posterior circumflex humeral vessels, to the upper arm where it's in contact with surgical neck of the humerus. 

BRANCHES
3. Sensory supply to small 'regimental patch' over shoulder.
4. Anterior - supplies the deltoid. 
5. Posterior - supplies teres minor, becomes upper lateral cutaneous nerve of the arm. 

Image: Gray, Henry. Anatomy of the Human Body. Philadelphia: Lea & Febiger, 1918; Bartleby.com, 2000. www.bartleby.com/107/ [Accessed 16 Nov. 2018].

Reference(s)

R.M.H McMinn (1998). Last’s anatomy: regional and applied. Edinburgh: Churchill Livingstone.
Gray, H., Carter, H.V. and Davidson, G. (2017). Gray’s anatomy. London: Arcturus.