Massage Therapy Journal Spring 2025

Spring 2025 • 55

The median nerve is another of the major nerves in the arm and hand. It is formed from the brachial plexus, specifically the nerve roots from C5 to T1. In the arm, the median nerve courses lateral to the brachial artery and then crosses over the artery to lay medial to the artery. Before the median nerve enters the forearm, it passes between the brachialis and biceps brachialis tendons, and then passes through the two heads of the pronator teres muscle. It will then enter the hand in the carpal tunnel, which is deep to the flexor retinaculum. The median nerve provides motor innervation to several muscles in the forearm and hand, including the muscles that control flexion of the wrist and fingers. It also carries sensory information from the skin of the first, second, third and the lateral half of the fourth finger. 55 The radial nerve is the largest and one of the major nerves in the arm. It plays a crucial role in the innervation of the upper limb and is part of the brachial plexus, primarily from nerve roots C5 to C8. The radial nerve travels down the posterior humerus in the radial groove, which is between the medial and lateral heads of the triceps brachii muscle, and then passes through the cubital fossa—sometimes called the antecubital fossa—where it divides into the superficial (sensory) branch and the deep (motor) branch. extending the wrist and fingers. This nerve also carries sensory information from the posterior (dorsal) hand and forearm. 56 The musculocutaneous nerve is a branch of the brachial plexus, specifically beginning from the nerve roots C5 to C7. As this nerve enters the axilla, it gives off fibers to the coracobrachialis muscle. It then runs in the flexor compartment between the biceps brachii and brachialis muscles while giving motor function to both of those muscles. After supplying small branches to the humerus, it courses through the deep fascia The radial nerve functions include supinating the radioulnar joints, and

and emerges just lateral to the biceps brachii. The musculocutaneous nerve then continues as the lateral cutaneous nerve of the forearm, where it receives sensory input from the anterolateral aspect of the forearm. 57 Thoracic Nerves The thoracic nerves are a series of spinal nerves that arise from the thoracic region of the spinal cord and innervate various structures in the chest, abdomen and back. There are 12 pairs of thoracic nerves, labeled T1 to T12, corresponding to each of the 12 thoracic vertebrae (T1-T12). Each thoracic nerve exits the spinal cord through the intervertebral foramina located between adjacent thoracic vertebrae. Notable characteristics include: • Sensory distribution : The sensory branches of the thoracic nerves supply sensation to the skin, muscles and organs of the thorax and upper abdomen. The sensory distribution of each thoracic nerve corresponds to a specific dermatome, which is an area of skin supplied by a single spinal nerve. • Intercostal nerves : The nerves that arise from the anterior rami (anterior divisions) of the thoracic nerves are known as intercostal nerves. These nerves run along the intercostal spaces between adjacent ribs and provide sensory innervation to the skin, muscles and pleura of the thorax. They also contribute to motor function, supplying the intercostal muscles and abdominal muscles. • Visceral branches : In addition to sensory and motor innervation to the musculoskeletal structures of the thorax, the thoracic nerves also provide autonomic innervation to the organs of the thoracic and abdominal cavities. These visceral branches • Sympathetic chain : The thoracic nerves also contribute fibers to the sympathetic nervous system, which is involved in the body’s fight or-flight response. These sympathetic fibers travel through the sympathetic chain ganglia located adjacent to the vertebral column. 58,59 regulate functions such as heart rate, respiration, digestion and blood flow.

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