Median Nerve For more information, please visit our Peripheral Nerve Neurosurgery Program site The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus. The median nerve is formed from parts of the medial and lateral cords of the brachial plexus, and continues down the arm to enter the forearm with the brachial artery. It originates from the brachial plexus with roots from C5, C6, C7, C8, & T1. The median nerve is the only nerve that passes through the carpal tunnel, where it may be compressed to cause carpal tunnel syndrome. Other injuries of the median nerve can lead to various deformities of the hand.