Brachial Plexus and Peripheral Nerves
by Annie Burke-Doe, PT, MPT, PhD
Practicing physical therapist and associate professor at the University of St. Augustine for Health Sciences in San Diego, California
Slide 1: Brachial Plexus and Peripheral Nerves
Welcome to neuroanatomy in physical therapy. I am Dr. Annie Burke-Doe, the practicing physical therapist and an associate professor at the University of St. Augustine for Health Sciences in San Diego, California. This lecture series has been developed for physical therapists embarking on the study of neurology. In this presentation, we will focus on the anatomy of the cervical spinal roots and their relationship to the vertebral structures, regions on innervation, and common clinical disorders that will be presented as cases with questions and answers.
Slide 2: Brachial Plexus
Pictured here on slide 2, we see the brachial plexus, which innervates the pectoral girdle and the upper limb, with contributions from the ventral rami of spinal nerves C5 through T1. The nerves that form this plexus originate from the trunks and cords. Trunks are large bundles of axons contributed by several spinal nerves. Cords are smaller branches that originate at trunks. Both trunks and cords are named according to their location relative to the axillary artery, a large artery supplying the upper limb. Therefore, we have superior, middle, and inferior trunks and lateral, medial, and posterior cords. As a physical therapy student and future practitioner, it will be important to have a working knowledge of the brachial plexus. One way to remember the brachial plexus organization is using the acronym ROBERT TAYLOR DRINKS COLD BEER.
Slide 3: Brachial Plexus—Learn to Draw!
Romm and Chu provide an illustrative way for students to learn to draw the brachial plexus in five minutes or less. Spending time on learning to draw the plexus will help you through those difficult anatomy exams, and understanding the plexus will help you clinically determine where damage in the peripheral pathway exists. Use the mouse to click forward to begin each element. Start by drawing two headless arrows to the right. Add a headless arrow to the left. Add a "W." Draw an "X." Add just a branch of the "Y." Label C5, C6, C7, C8, and T1. Then label the major branches: musculocutaneous, median, ulnar, radial, and axillary.
Slide 4: Brachial Plexus
This diagram now includes the main branches and main nerve roots with proper connections. Physical therapists will use more complex diagramming that includes four "3s." Again, use your mouse to forward through the diagram. The first "3" is the branches to C5, 6, 7, which form the long thoracic nerve. Next, each of the headless arrows has three nerves attached to it. To the top headless arrow, add its "3." Label these dorsoscapular nerve, suprascapular nerve, lateral pectoral nerve. Add the "3" to the middle headless arrow. Label the second headless arrow: subscapular and thoracodorsal nerve. Add the final "3" on the bottom headless arrow. Label the last "3": medial pectoral, medial brachial cutaneous, and medial antebrachial cutaneous. Remember, the brachial cutaneous goes to the brachium or arm, and the medial antebrachial cutaneous goes to the antebrachium or forearm. The nerve to the forearm starts distally. Now, label the roots, trunks divisions, cords, and terminal branches. Finally, physical therapists also need to know the nerve to the subclavius. Here is your complete brachial plexus diagram. Remember, practice makes perfect.
Slide 5: Brachial Plexus
Moving distally, the lateral cord forms the musculocutaneous nerve and, together with the medial cord, forms the median nerve. The posterior cord nerve branches will form the axillary, radial, thoracodorsal, and subscapular nerves. The medial cord's other major nerve is the ulnar nerve.
Slide 6: The Musculocutaneous Nerve
The musculocutaneous nerve , pictured here, innervates the biceps, brachialis, and coracobrachialis. The biceps is a flexor of the shoulder and elbow and a supinator of the forearm. To understand its full function, envision a man driving a corkscrew into a bottle of wine (supinating), pulling out the cork (elbow flexion), and drinking the wine (shoulder flexion). Sensation is provided to the lateral surface of the forearm through the lateral antebrachial cutaneous nerve branch.
Slide 7: The Axillary Nerve
The axillary nerve pictured here innervates the deltoid and the teres minor. The deltoid is a three-part muscle: the anterior deltoid flexes, the middle deltoid abducts, and the posterior deltoid extends the shoulder. Of the three motions, the deltoid acts most powerfully in abduction. The C5 neurologic level supplies sensation to the lateral arm from the summit of the shoulder to the elbow. The purest patch of axillary nerve sensation, pictured here on the right, lies over the lateral portion of the deltoid muscles. This localized sensory area within the C5 dermatome is useful for indicating specific trauma to the axillary nerve, as well as general trauma to the C5 nerve root.
Slide 8: The Radial Nerve
The radial nerve innervates the triceps, extensor carpi radialis and ulnaris, supinator, and extensor pollicis. Motor functions include: extension at all arm, wrist, and proximal finger joints below the shoulder; forearm supination; and thumb abduction in the plane of the palm. The triceps is the primary elbow extensor. It is important because it permits the patient to support himself or herself on a cane or standard crutch.
Slide 9: The Radial Nerve
The radial nerve supplies sensation, as pictured here, to the skin over the posterolateral surface of the arm through the posterior brachial cutaneous nerve, posterior antebrachial cutaneous nerve, and the superficial radial nerve branch.
Slide 10: The Median Nerve
The median nerve innervates flexor carpi radialis, palmaris longus, pronator quadratus, pronator teres, and the digital flexors. Motor functions include thumb flexion and opposition, flexion of digits 2 and 3, wrist flexion and abduction, and forearm pronation. Sensation, pictured here at the top, includes the skin over the anterolateral surface of the hand. When the median nerve is damaged, the thenar eminence may atrophy, and the patient will not be able to oppose the thumb, resulting in ape-hand deformity, pictured on the right side of the slide.
Slide 11: The Ulnar Nerve
The ulnar nerve innervates flexor digitorum profundus, adductor pollicis, and small digital muscles. Motor function includes: finger adduction and abduction other than the thumb; thumb adduction; flexion of the digits 4 and 5; as well as wrist flexion and wrist adduction. Sensation, which is pictured at the top, includes the skin over the medial surface of the hand through the superficial branch. With damage to the ulnar nerve, a claw-hand deformity is manifested by flattening of the transverse metacarpal arch and longitudinal arches with hyperextension of the MCP joints and flexion of the PIP and the DIP joints - deformities produced by the imbalance of this intrinsic and extrinsic musculature.
Slide 12: Case 1: Pain in the Neck
The following cases are designed for you to read and answer the questions in preparation for your course work in neurology and licensure preparation. Please proceed through each case and determine the answer to the questions.
Slide 37: References
- Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science. 4th ed. New York: McGraw-Hill; 2000.
- Seigal A, Sapru HN. Essential Neuroscience. New York: Lippincott Williams & Wilkins; 2006.
- Blumenfeld, H. Neuroanatomy through Clinical Cases. Sunderland, MA: Sinauer Associates; 2002.
- Goodman C, Fuller K, et al. Pathology Implications for the Physical Therapist. 3rd ed. St. Louis, MO: Saunders; 2008.
- Panus PC, Jobst EE, Masters SB, Katzung B, Tinsley SL, Trevor AJ: Pharmacology for the Physical Therapist, 11e. New York, NY: McGraw-Hill; 2009. http://www.accessphysiotherapy.com/content/6092707. Accessed March 6, 2012.
- Romm, DS, Chu, DA. Learn the brachial plexus in five minutes or less. Chicago, Illinois: American Medical Association. http://www.ama-assn.org/resources/doc/mss/brachial_plex_how_to.pdf. Accessed May 10, 2011.