ABSTRACT
Study objectives Dene cauda equina and explain how it is formed Distinguish between a nerve and a tract Explain the function of the gray matter of the spinal cord Describe the location and function of each of the four types of neurons found in the gray matter of the spinal cord Explain the function of the white matter of the spinal cord Describe the composition of the ascending tracts including both the origin and termination of each of the neurons Distinguish between corticospinal tracts and multineuronal tracts Discuss the mechanisms by which spinal anesthesia and epidural anesthesia exert their effects Dene the various categories of reexes List the components of the reex arc Explain the mechanism of the withdrawal reex Explain the mechanism of the crossed-extensor reex
. Introduction The lowest level of the central nervous system (CNS), both anatomically and functionally, is the spinal cord. Continuous with the brainstem, it exits the skull through the foramen magnum. The spinal cord then passes through the vertebral canal of the vertebral column to the level of the rst or second lumbar vertebrae.
