Therapeutic exercise and related manual therapy techniques would not be possible without the nervous system and all its components activating, controlling, and modifying motor responses as well as receiving and interpreting feedback from the variety of sensory receptors throughout the body. Because of their intimate proximity to all the structures in the trunk and extremities, nerves may become stressed or injured with various musculoskeletal conditions, postures, and repetitive microtraumas resulting in neurological symptoms, structural and functional impairments, activity limitations, and participation restrictions. Highlights of the anatomy and results of injury to the peripheral nervous system are reviewed in the first section of this chapter for the purpose of laying the foundation for management guidelines, including therapeutic exercise and manual therapy interventions, that are described in the remainder of the chapter. In the treatment of patients with musculoskeletal impairments, often the therapist does not think of the components of the central nervous system. Even though this chapter primarily deals with the peripheral nervous system, acknowledgment that the central nervous system plays a key role in the initiation and control of movement is a must. The reader is referred to Chapter 8 for consideration of motor control in the total rehabilitation of the individual.
The development of a plan of care and intervention techniques differs for patients with impairments due to nerve involvement. Nerve injuries may result in significant activity limitations and participation restrictions due to paralysis and resulting deformity. Utilizing the principles presented in this chapter, along with the knowledge and skills of examination and evaluation of the neural, muscular, and skeletal systems, the reader should be able to design therapeutic exercise programs for patients with limitations due to injury or mobility restrictions of the peripheral nervous system. Also included in this chapter is a section on complex regional pain syndromes type I (reflex sympathetic dystrophy) and type II.
Review of Peripheral Nerve Structure
Peripheral components of the neuromuscular system include the alpha and gamma motor neurons, their axons, and the skeletal muscles they innervate; the sensory neurons and their receptors located in the connective tissues, joints, and blood vessels; and the neurons of the autonomic nervous system. Connective tissue surrounds each axon (endoneurium) as well as fascicles (perineurium) and entire nerve fibers (epineurium).48,69 The axolemma is the surface membrane of axon. Schwann cells lie between the axolemma and endoneurium; they form myelin, which functions to insulate the axon as well as speed the conduction of action potentials along the nerve fiber. The exceptions are very small fibers that are unmyelinated. A peripheral nerve may consist of a single fascicle or consist of several fascicles.48 The structure of a peripheral nerve with its connective tissue and vascular layers is illustrated in Figure 13.1, and the location of their cell bodies is summarized in Box 13.1.