Application #37: Brachial Plexus at Shoulder Copy

Brachial Plexus of the Shoulder

Anatomy:
The brachial plexus is a major network of nerves transmitting signals responsible for motor and sensory innervation of the upper extremities, including the shoulder, arm, and hand. It originates from the ventral rami of C5 through T1 spinal nerves. Proximally to distally, the brachial plexus is comprised of roots, trunks, divisions, cords, and terminal branches. Brachial plexus injuries qualify as one of the most debilitating injuries afflicting the upper extremity.

Innervation:
The musculocutaneous nerve arises from C5 and C6 spinal nerves. It innervates all the muscles of the arm anteriorly, enabling motor functions such as flexion of the elbow and supination by the biceps brachii. The median nerve originates from C5 to T1 spinal nerves. It primarily innervates the anterior forearm (with a section innervated by the ulnar nerve) and the hand (thenar and central sections). The median nerve allows pronation of the forearm and flexion of the wrist and digits, together with the opposition of the thumb. The ulnar nerve originates from C8 to T1 spinal nerves. It constitutes the innervation of the anterior forearm (with a section innervated by the median nerve) and the hand (hypothenar and central sections). The central section, which involves the palmar and dorsal aspects, is responsible for the adduction and abduction of second to fifth digits, respectively. Unlike the median nerve, which allows opposition, the ulnar nerve is responsible for the adduction of the thumb.

Vasculature:
The brachial plexus receives the majority of its blood supply from the subclavian artery and its derivatives. The vertebral artery, through its anterior and posterior spinal branches, provides blood supply to the cervical rootlets. The trunks receive blood supply from the superior intercostal and deep cervical arteries, or directly from the subclavian artery. The cords are supplied by the subclavian, subscapular, and axillary arteries.

Possible Effects of a Strike:
  • can cause one of the most debilitating injuries afflicting the upper extremity.
  • injury to the shoulder
  • paralysis of the arm
  • numbness of the arm
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