The roots of the brachial plexus are the anterior (ventral) rami of spinal nerves C5, C6, C7, C8 and T1. They leave the intervertebral foramina and pass between the anterior and middle scalene muscles, where they unite to form the three trunks. A small extra contribution from C4 (a prefixed plexus) or T2 (a postfixed plexus) is common.
| Origin | Anterior rami of spinal nerves C5-T1, with variable contributions from C4 or T2 |
|---|---|
| Course | Emerge from the intervertebral foramina behind the vertebral artery and pass through the interscalene gap between the anterior and middle scalenes, uniting near the lateral border of the anterior scalene to form the trunks |
| Motor |
|
| Sensory |
|
Root level injuries are the most serious brachial plexus injuries, because a root torn out of the spinal cord (avulsion) cannot be repaired directly and needs nerve transfers. Clues to a preganglionic avulsion are Horner syndrome (T1), winging of the scapula (long thoracic nerve), rhomboid weakness (dorsal scapular nerve) and preserved sensory nerve action potentials despite numb skin. The interscalene block deposits local anaesthetic around the roots and upper trunks between the scalene muscles for shoulder surgery.
Violent traction on the arm or neck, typically in motorcycle accidents or difficult births, pulls the rootlets out of the spinal cord. MRI often shows a pseudomeningocele, and function is restored only by nerve transfers or tendon transfers.
A disc herniation or foraminal narrowing compresses a single root, causing pain, numbness and weakness in its dermatome and myotome, such as C6 radiculopathy with thumb numbness and weak biceps and wrist extension.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
