Innervation of the upper limb is by the brachial plexus, which is formed by the anterior rami of cervical spinal nerves C5 to C8, and T1 (Fig. 7.14). This plexus is initially formed in the neck and then continues through the axillary inlet into the axilla. Major nerves that ultimately innervate the arm, forearm, and hand originate from the brachial plexus in the axilla.