GROSS ANATOMY

Detailed explanation-1: -The radial nerve (C5-T1) is a continuation of the posterior cord and provides motor innervation to all muscles in the posterior arm and forearm. The main trunk of the radial nerve innervates the triceps brachii, anconeus, extensor carpi radialis longus, and brachioradialis muscles.

Detailed explanation-2: -The long thoracic nerve is derived from C5, C6, and C7 roots immediately after their emergence from the intervertebral foramina. The long thoracic nerve crosses the first rib and then descends through the axilla behind the major branches of the plexus. It innervates the serratus anterior muscle.

Detailed explanation-3: -The radial nerve starts at the lower armpit. It originates from several nerve roots (where a nerve connects to the central nervous system) that run from the: C5 to C8 cervical vertebrae, the lowest spinal bones in the neck.

Detailed explanation-4: -The radial nerve is formed from the C5, C6, C7, C8 and T1 nerve roots of the brachial plexus. The brachial plexus is a group of nerves that branches from the cervical spine (neck). The brachial plexus travels under the clavicle and through the armpit (axilla).

Detailed explanation-5: -Subclavian nerve This nerve emerges from the superior trunk of the brachial plexus and contains fibers of C5 and C6 spinal nerves. The subclavian nerve provides motor innervation to the subclavius muscle.