Editing Axillary nerve (section)

==Structure==
The nerve lies at first behind the [[axillary artery]],<ref>{{Citation|last1=Kretschmer|first1=Thomas|title=Chapter 36 - Iatrogenic Injuries of the Nerves|date=2015-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780128026533000853|work=Nerves and Nerve Injuries|pages=557–585|editor-last=Tubbs|editor-first=R. Shane|place=San Diego|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-802653-3.00085-3|isbn=978-0-12-802653-3|access-date=2020-10-25|last2=Heinen|first2=Christian|editor2-last=Rizk|editor2-first=Elias|editor3-last=Shoja|editor3-first=Mohammadali M.|editor4-last=Loukas|editor4-first=Marios|url-access=subscription}}</ref> and in front of the [[subscapularis]],<ref name=":0" /> and passes downward to the lower border of that muscle.

It then winds from anterior to posterior around the neck of the [[humerus]], in company with the [[posterior humeral circumflex artery]],<ref name=":1" /> through the [[quadrangular space]] (bounded above by the [[teres minor]], below by the [[teres major]], medially by the long head of the [[triceps brachii]], and laterally by the [[surgical neck]] of the humerus),<ref name=":0" /> and divides into an anterior, a posterior, and a collateral branch to the long head of the [[triceps brachii]] branch.

* The ''anterior branch'' (upper branch) winds around the [[surgical neck of the humerus]],<ref>{{Citation|last=Voight|first=M. L.|title=Chapter 39 - Shoulder Instability|date=2017-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323286831000394|work=Orthopaedic Physical Therapy Secrets (Third Edition)|pages=335–341|editor-last=Placzek|editor-first=Jeffrey D.|publisher=Elsevier|language=en|doi=10.1016/b978-0-323-28683-1.00039-4|isbn=978-0-323-28683-1|access-date=2020-10-25|editor2-last=Boyce|editor2-first=David A.|url-access=subscription}}</ref> beneath the [[deltoid muscle]], with the posterior humeral circumflex vessels. It continues as far as the anterior border of the deltoid to provide motor innervation. The anterior branch also gives off a few small cutaneous branches, which pierce the muscle and supply in the overlaying skin.
* The ''posterior branch'' (lower branch) supplies the [[teres minor]] and the posterior part of the [[deltoid muscle|deltoid]].<ref name=":1" /> The posterior branch pierces the deep fascia and continues as the [[Superior lateral cutaneous nerve of arm|superior (or upper) lateral cutaneous nerve of arm]], which sweeps around the posterior border of the deltoid and supplies the skin over the lower two-thirds of the posterior part of this muscle, as well as that covering the long head of the triceps brachii.
* The motor branch of the long head of the [[triceps brachii]] arises, on average, a distance of 6&nbsp;mm (range 2–12&nbsp;mm) from the terminal division of the posterior cord termination.<ref name="seze"/>
* The trunk of the axillary nerve gives off an articular filament which enters the [[shoulder joint]] below the [[subscapularis]].

===Variation===
Traditionally, the axillary nerve is thought to only supply the [[Deltoid muscle|deltoid]] and [[Teres minor muscle|teres minor]]. However, several studies on [[cadaver]]s pointed out that the long head of [[triceps brachii]] is innervated by a branch of the axillary nerve.<ref>{{cite journal|last1=Rezzouk|first1=J|last2=Durandeau|first2=A|last3=Vital|first3=JM|last4=Fabre|first4=T|title=Long head of the triceps brachii in axillary nerve injury: anatomy and clinical aspects|journal=Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur|date=October 2002|volume=88|issue=6|pages=561–564|pmid=12447125}}</ref><ref name="seze">{{cite journal|vauthors=de Sèze MP, Rezzouk J, de Sèze M, Uzel M, Lavignolle B, Midy D, Durandeau A | title   = Does the motor branch of the long head of the triceps brachii arise from the radial nerve?| journal = Surg Radiol Anat | volume = 26 | issue = 6 | pages = 459–461 | year = 2004
| pmid    = 15365769| doi     = 10.1007/s00276-004-0253-z| s2cid = 10052988}}</ref><ref><!--This is before Pulsus journals were acquired by OMICS, this is not a predatory source-->{{cite journal|last1=Komala|first1=Nanjundaiah|last2=Shashanka|first2=MallasandraJayadevaiah|last3=Sheshgiri|first3=Chowdapurkar|title=Long head of triceps supplied by axillary nerve|journal=International Journal of Anatomical Variations|date=16 April 2012|volume=5|pages=35–37|url=https://www.pulsus.com/scholarly-articles/long-head-of-triceps-supplied-by-axillary-nerve.html|access-date=26 January 2018}}</ref>