++
CHAPTER OBJECTIVES
At the completion of this chapter, the reader will be able to:
Describe the various components of the central nervous system (CNS) and peripheral nervous system (PNS).
Describe the anatomic and functional organization of the nervous system.
Describe the various components and distributions of the cervical, brachial, and lumbosacral plexuses.
Describe the difference between balance and proprioception.
Describe the role proprioception plays in function.
Describe and differentiate among the various joint mechanoreceptors.
Recognize the characteristics of a lesion to the CNS.
Outline the neurophysiology of pain and the methods by which pain is controlled.
Define concussion and describe its associated signs and symptoms.
List the findings and the impairments associated with the more common peripheral nerve lesions.
Perform a comprehensive examination of the neurologic system.
Describe some of the common pathologies of the nervous system.
++
OVERVIEW
In order to perform a comprehensive neuromusculoskeletal examination, the clinician must have a clear understanding of the anatomy, physiology, and function of the various components of the nervous system, and be able to recognize those signs and symptoms that indicate a compromise of the nervous system.
The nervous system is composed of only two principal types of cells—neurons and supporting cells. The neuron, which is classified according to structure or function, serves to store and process information, and is the functional unit of the nervous system. The supporting cell called the neuroglial cell, or simply glial, functions to provide structural and metabolic support for the neurons.1 Unlike many cells, neurons cannot divide by mitosis, but they do have some capability to regenerate. In contrast, glial cells retain limited mitotic abilities.
++
The human nervous system can be subdivided into two anatomic divisions: the CNS, comprising the brain and the spinal cord, and the PNS, formed by the nerves and ganglia (cluster of nerve cell bodies located outside of the CNS). The PNS is further subdivided into somatic and autonomic divisions. The somatic division, which includes the cranial (with the exception of cranial II) and the spinal nerves, innervates the skin, the muscles, and the joints, while the autonomic division innervates the glands and the smooth muscle of the viscera and the blood vessels.1
++
Neurons can broadly be divided into four types based on anatomical and functional criteria2:
++
Aα fibers: Thick myelinated fibers transmitting signals to and from muscles.
Aβ fibers: Thick myelinated fibers conducting sensations such as touch and proprioception.
Aδ fibers: Thin myelinated fibers transmitting nociceptive signals evoked by stimuli such as cold and pinprick.
C fibers: Small-diameter unmyelinated nerve fibers subserving nociception evoked by heat or mechanical stimuli as well as innocuous temperature changes (e.g., warm detection) and itch. C fibers can be further subdivided into four main groups:
C-polymodal fibers, which are activated by mechanical thermal and chemical stimuli.
Mechanoreceptors, which are ...