What is the axillary nerve?
Your axillary nerve, also known as the circumflex nerve, is one of five peripheral nerves that run through your shoulder. Axillary nerves start in your neck at the brachial plexus (a network of nerves in your shoulder). This network of nerves enables movement and sensation to your upper limbs.
What other nerves are near the axillary nerve?
Other nerves include your:
- Median nerve, which goes into the front of your forearm, hand and most of your fingers.
- Musculocutaneous nerve, which goes into muscles in the front of your upper arm and near your elbow.
- Radial nerve, which goes into muscles in the back of your arm (triceps) and in your wrists.
- Ulnar nerve, which goes into your forearm and hand.
What is the function of the axillary nerve?
The axillary nerve helps you move muscles in your upper limbs, near your shoulder. It also provides sensation to this area, including:
Which muscles are innervated by the axillary nerve?
- Deltoid, which allows you to lift your arm.
- Teres minor, which makes it possible to rotate your arms away from your body.
- Part of your triceps that permits you to straighten your elbow.
What is the anatomy of the shoulder nerve?
Your axillary nerve starts in the fifth and sixth bones (vertebrae) in your lower cervical spine. Your cervical spine contains the bones that make up your neck.
The axillary nerve then:
- Travels under your collar bone.
- Passes through the quadrangular space, a gap between muscles and other tissue.
- Goes behind the top of your upper arm bone (humerus).
Next, the axillary nerve divides into three branches:
- Anterior (“upper”) branch connects to and provides motor function to your anterior deltoid muscle (front shoulder).
- Articular branch goes into the upper part of your triceps (back of your upper arm) and your glenohumeral (shoulder) joint.
- Posterior (“lower”) branch connects to and provides motor function to your posterior deltoid (back shoulder) and teres minor muscles, along with the skin in this area of your arm.
Conditions and Disorders
What conditions affect shoulder nerve functioning?
Conditions affecting this nerve include injuries from:
- Accidents where your head and shoulder move abruptly in opposite directions.
- Crutches or support devices that put abnormal pressure on your axillary nerve.
- Dislocated shoulder, which can occur from a fall, like off a ladder or bicycle.
- Fractures at the top of your arm bone (humerus).
- Orthopedic surgery complications from procedures such as shoulder arthroscopy.
Childbirth sometimes affects shoulder functioning in newborns. During birth, it may be necessary to grab a baby by their arm or near their shoulder. Their shoulders can also become stuck in a birthing person's pelvis, putting abnormal pressure on them. These situations can damage the baby’s axillary nerve.
Other conditions are:
- Cervical radiculopathy: A pinched nerves in your neck. The condition may cause discomfort in your shoulder.
- Erb-Duchenne and Dejerine-Klumpke palsies: Arm paralysis due to a brachial plexus (network of nerves in your shoulder) injury.
- Parsonage-Turner syndrome: A rare condition that occurs when your immune system attacks healthy tissue (autoimmune inflammation).
- Herpes zoster.
- Quadrilateral space syndrome: When inflammation in the muscles of your quadrilateral space press on your axillary nerve.
Should I be concerned if I have an axillary nerve injury?
Nerve injuries can take a long time to heal. But they often get better on their own or with physical therapy. Severe injuries may need surgery, such as a nerve graft. It can take months to regain sensation or muscle control.
How is this condition diagnosed?
To make a diagnosis, your healthcare provider may:
- A complete history and neurologic evaluation.
- NCS/EMG (nerve conduction study/electromyography). This is an electrophysiologic test that’s used to check peripheral nerve and muscle function.
- X-rays to assess the integrity of your shoulder joint and bones.
- MRI (magnetic resonance imaging). This can provide valuable information about the integrity of deep shoulder structures, including your nerves.
- Neuromuscular ultrasound. More providers are using neuromuscular ultrasound as an important support tool in the assessment of many upper extremity neurologic disorders.
How can I prevent an axillary nerve injury?
Steps you can take to avoid a shoulder nerve injury include:
- Receiving care from an experienced orthopaedic surgeon if you need a shoulder procedure. A surgeon specializing in upper extremities (hand surgeon) is an excellent option.
- Being cautious when climbing a ladder. You may want to ask someone to hold the ladder in place or hand you things to avoid falling.
- Using a seatbelt or other safety equipment to lower your risk of motor vehicle accidents.
- Learning how to use crutches correctly to avoid putting pressure on your axillary nerve.
When should I call a healthcare provider about problems with my shoulder nerve?
You should contact your healthcare provider if you’re experiencing shoulder discomfort. Symptoms of an axillary nerve injury include:
- Difficulty moving your shoulder or arm.
- Pain, especially when lifting your arms.
A note from Cleveland Clinic
The axillary nerve connects to your shoulder. It provides sensation and allows you to rotate and straighten your arm. Axillary nerve injuries have a variety of causes. They can lead to arm paralysis and other difficulties. You can avoid certain injuries by using safety equipment and taking extra care to prevent falls. If you do get injured or have other problems with your shoulder, don't hesitate to reach out to your healthcare provider.
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