Upper trunk

Overview
The upper trunk (or superior trunk) is a trunk of the brachial plexus which derives from the C5 and C6 roots.

Damage to the upper trunk causes

 * Arm hangs by side,
 * Elbow can’t flex,
 * Arm medially rotated,
 * Forearm pronated,
 * ‘waiter’s tip’,
 * Loss of sensation over deltoid (C5) and lateral upper limb (C6).

The musculocutaneous and median nerves derive largely from this trunk.