The axillary nerve
Axillary nerve · nervus axillaris
A nerve that wraps around the back of the upper arm to power the deltoid.
What it does
The axillary nerve leaves the brachial plexus in the armpit and curls around the back of the humerus just below the shoulder. It supplies the deltoid and teres minor and carries feeling from a patch of skin over the outer shoulder.
Surprising fact
That patch of skin is called the "regimental badge" area, because it sits where military badges were sewn on, and numbness there suggests the nerve is injured.
Why it matters
A dislocated shoulder or a break at the top of the humerus can stretch this nerve, making it hard to lift your arm out to the side.
Nearby
Read more
Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.