Nerves of the arm and the shoulder - Posterior view (English)

In relation to the humerus, many nerves of the brachial plexus arise and course posterior to it. The ulnar nerve is a terminal branch of the medial cord of the brachial plexus; it is branchless within the arm. The posterior cord of the brachial plexus gives rise to the subscapular (not depicted here), thoracodorsal and axillary nerves innervating the subscapularis and teres major muscles, the latissimus dorsi and deltoid muscles, respectively. The radial nerve, a larger terminal branch of the posterior cord, supplies all muscles of the posterior compartment of the arm and forearm. It equally provides sensory innervation to the skin of the posterior and inferolateral arm and forearm (posterior/inferior lateral brachial cutaneous nerves). In the clavicular and shoulder region, the supraclavicular nerves arising from the cervical plexus provide sensation over the clavicle, anteromedial shoulder and proximal thorax. The suprascapular nerve arises from the superior trunk of the brachial plexus and passes through the scapular notch to innervate the supraspinatus and infraspinatus muscles, as well as the glenohumeral joint along its course. The long thoracic nerve originates from the posterior aspect of anterior rami of spinal nerves C5, C6 and C7 and supplies the serratus anterior muscle. Arising from the anterior ramus of spinal nerve C5, the dorsal scapular nerve descends deep to the levator scapulae and rhomboid muscles to supply them.