Page Contents
NEURAL PATHWAY
The axillary nerve originates from spinal roots C5 and C6.
Spinal roots C5 and C6 → Brachial Plexus (Posterior Cord) → Axillary Nerve
![Anatomical location of the axillary nerve relative to the brachial plexus (source)](http://www.stepwards.com/wp-content/uploads/2016/08/750px-Brachial_plexus_2.svg_.png)
After leaving the brachial plexus the axillary nerve will wrap around the humerus and innervate the upper arm.
![The axillary nerve will innervate structures of the upper arm (source)](http://www.stepwards.com/wp-content/uploads/2016/08/Axillary-nerve-BE-768x576.jpg)
FUNCTION
Motor Function:
Abduction of the arm: this nerve will innervate the deltoid muscle which controls abduction of the arm.
Sensory Function:
Upper arm sensation: the axillary nerve controls sensory innervation of the upper arm (depicted more below).
![Pattern of radial nerve sensory innervation (source)](http://www.stepwards.com/wp-content/uploads/2016/08/Sensory-Innervation-of-the-Axillary-Nerve.jpg)
CAUSE OF INJURY
Shoulder dislocation: particularly anterior-inferior dislocations of the shoulder joint can damage this nerve.
Compression of the axilla such as with a crutch.
Humerus fracture: specifically a fracture of the surgical neck of the humerus can damage this nerve.
![This X-ray film shows a fracture of the surgical neck of the humorous. It is this type of injury that can often affect the axillary nerve (source)](http://www.stepwards.com/wp-content/uploads/2016/08/c6c1001bb3b645bf45c20f54d6f9f5.jpg)
CLINICAL PRESNENTATION
Sensory loss in the distribution of innervation outlined above (lateral aspect of upper arm)
Inability to abduct the arm between 15-90° (range controlled by the deltoid muscle).
ARCHIVE OF STANDARDIZED EXAM QUESTIONS
This archive compiles standardized exam questions that relate to this topic.
Page Updated: 08.21.2016