Brachial plexus anatomy is complex, but can be described in terms of basic function. The brachial plexus is derived from 5 "roots" or spinal nerves that exit the spinal cord in the neck. The nerves then pass through the axilla or armpit behind the collarbone (clavicle), and split into the final nerve branches that supply the muscles and skin of the shoulder, arm, elbow and hand.

The roots are named for the level of spinal cord that they exit. The upper roots (C5 and C6) exit from the cervical (meaning "neck") 5th and 6th vertebrae. The middle root (C7) exits above the 7th cervical vertebrae, and the lower roots exit from C8 (below the 7th cervical vertebra) and T1 (below the 1st thoracic vertebra). The upper roots supply upper structures (C5 to shoulder, C6 and C7 to elbow), and the lower roots supply the forearm and hand.

Injury to upper roots (the most common injury) is known as Erb’s palsy after the physician who described it. Erb’s palsy (paralysis) affects the shoulder and elbow, because the upper roots supply these structures. Injury to the lower roots is known as Klumpke’s paralysis, but is relatively uncommon, and very rarely exists by itself. Because the lower roots are injured, the hand is predominantly affected. If the lower roots are injured, the injury is generally so severe that all the roots of the plexus are involved, and the injury includes all parts of the arm. Upper root (Erb’s) injury is seen about 60% of the time, isolated Klumpke’s perhaps 5% of the time, and mixed injuries involving all elements of the plexus to some degree, make up 35% of patients.

Nerve Scar Excision (Neurolysis), Nerve Grafting, Nerve Transfer and Neurotization.

Specific nerve surgeries that we use are: nerve scar excision (neurolysis), nerve grafting, nerve transfer and neurotization. It is sometimes necessary to perform tendon lengthening procedures in infancy in conjunction with the nerve procedures. These procedures are complex and must be used judiciously in order not to burn bridges for future reconstructive options.