Axillary nerve

1. What nerve roots does the axillary nerve originate from?
2. What is the path of the axillary nerve?
3. What muscles does the axillary nerve innervate? What sensory branch does it give off?
4. How is the axillary nerve usually injured and what is the presentation?

Answers:
1. C5 and C6, contributing to the upper trunk and posterior cord.
2. It passes inferior to the glenohumeral jt, to the posterior aspect of the humerus.
3. Teres minor and deltoid. It gives off the upper lateral cutaneous nerve.
4. It is injured by shoulder dislocation, humeral head fracture, or improper crutch use. Patient complains of weakness of shoulder flexion, abduction, and external rotation. There may also be lateral shoulder sensation abnormality.