Brachial plexus
The brachial plexus is a group of nerves. It runs from the vertebral column to the arm.
Structure
The brachial plexus is divided into five roots, three trunks, six divisions, three cords, and five branches.
Roots
The five roots come out of the spinal cord. They are each named after the part of the spinal cord they come out of: C5, C6, C7, C8, and T1.
Trunks
These roots join to form three trunks:
- "upper" (C5-C6)
- "middle" (C7)
- "lower" (C8-T1)
Divisions
Each trunk then splits into two divisions:
- anterior (front) divisions of the upper, middle, and lower trunks
- posterior (back) divisions of the upper, middle, and lower trunks
Cords
These six divisions join up again to become the three cords.
- The posterior cord is formed from the three posterior divisions of the trunks (C5-C8,T1)
- The lateral cord is formed from the anterior divisions of the upper and middle trunks (C5-C7)
- The medial cord is simply a continuation of the anterior division of the lower trunk (C8,T1)
Diagram
Brachial Plexus Media
The brachial plexus surrounds the brachial artery.
Nerves
The nerves that come out of the brachial plexus include:
- Radial nerve
- Axillary nerve
- Musculocutaneous nerve
- Median nerve
- Ulnar nerve