Brachial plexus

Plexus brachialis

NervousNervesWhole bodyLeft and right

View left in 3D View right in 3D

What it is
The nerve network of the upper limb, formed by the ventral rami of C5-T1. The five roots emerge between the anterior and middle scalene muscles, merge into upper, middle and lower trunks in the base of the neck, split into divisions behind the clavicle and regroup as lateral, posterior and medial cords around the axillary artery in the armpit.
Function
Mixes fibres from five spinal segments so that each arm nerve carries several segments; supplies every muscle of the shoulder girdle and limb and all the skin of the arm except the armpit.
Size
About 15 cm from the spine to the armpit; roots and trunks 3-6 mm thick
Clinical note
Birth or motorbike traction injuries damage the upper roots (Erb palsy, "waiter's tip") or the lower roots (Klumpke palsy, claw hand). Anaesthetists block the plexus above or below the clavicle to operate on the arm.

Contains Axillary nerve, Median nerve, Musculocutaneous nerve, Radial nerve, Ulnar nerve

Nearby nervous structures Accessory nerve (CN XI), Cardiac plexus, Cervical plexus, Left phrenic nerve, Left recurrent laryngeal nerve, Left vagus nerve (CN X), Right phrenic nerve, Right recurrent laryngeal nerve, Right vagus nerve (CN X), Spinal cord