Roots and trunks of brachial plexus

The brachial plexus is formed by the anterior rami of the spinal nerves C5 to T1. They are also known as the five roots of the brachial plexus. The roots merge to form three trunks of the brachial plexus:

• Superior trunk - formed by the anterior ramus of the C5 spinal nerve and anterior ramus of the C6 spinal nerve;
• Middle trunk - formed by the anterior ramus of the C7 spinal nerve;
• Inferior trunk - formed by the anterior ramus of the C8 spinal nerve and anterior ramus of the T1 spinal nerve.