The spinal cord is tubular in shape and has 32 segments with the gray matter in the center and white matter on the outside. Each segment has nerve rootlets on the dorsal and ventral surface with a sensory ganglion attached to the dorsal nerve rootlets. These dorsal root ganglia contain the primary cell bodies of the general sensory systems—pain, temperature, touch, and pressure from the neck, thorax, abdomen, and extremities.
The gray matter is shaped like a butterfly, and the gray matter in all levels has three zones: a dorsal horn, a ventral horn, and an intermediate zone. A lateral horn containing the preganglionic sympathetic neurons is found in levels T1–L2.
The surrounding white matter is divided into three columns, dorsal, ventral, and anterior. The white matter is organized with the ascending systems on the outside and the descending systems closer to the gray matter.
Keywords32 Segments Central gray White matter Dorsal and ventral nerves Ascending tracts Descending tracts
- Abel Majuid T, Bowsher D. The gray matter of the dorsal horn of the adult human spinal cord. J Anat. 1985;142:33–58.Google Scholar
- Asanuma H. The pyramidal tract. In: Brooks VB, editor. Handbook of physiology. Section I. The nervous system. Vol II. Motor control. Bethesda, MD: American Physiological Society; 1981. p. 703–33.Google Scholar
- Burton H, Craig A. Distribution of trigeminothalamic neurons in cat and monkey. Brain Res. 161:515–21.Google Scholar
- Carpenter, M.B. 1978. Core text of neuroanatomy, 4th. Baltimore, Lippincott Williams & Wilkins, 1991.Google Scholar
- Everts E. Role of motor cortex in voluntary movement in primates. In: Brooks VB, editor. Handbook of physiology. Section I. The nervous system. Vol II. Motor control. Bethesda, MD: American Physiological Society. p. 1083–120.Google Scholar
- Finger T, Silver W. Neurobiology of taste and smell. New York: Wiley; 1987.Google Scholar
- Hobson J, Brazier M, editors. The reticular formation revisited. Brain Res. 1983;6:1–564.Google Scholar
- Norgren R. Central mechansims of taste. In: Darian-Smith, editor. Handbook of physiology. Section I. The nervous system. Vol III. Sensory processes. Bethesda, MD: American Physiological Socienty; 1984. p. 1087–128.Google Scholar
- Riley HA. Brain Stem and Spinal Cord. New York: Hafner; 1960.Google Scholar
- Sinclair D. Touch in primates. Ann Rev Neurosci. 1982;5:155–94.Google Scholar
- Wall P, Melzak R. Textbook of pain. Edinburgh: Churchill Livingston; 1989.Google Scholar
- Victor M, Ropper AH. Principles of neurology. 7th ed. New York: McGraw Hill; 2001.Google Scholar
- Brodal A. The cranial nerves. Anatomy & anatomical clinical correlation. London: Oxford Blackwell; 1965.Google Scholar
- Clemente C. Gray’s anatomy. 30th ed. Philadelphia: Lea & Febiger; 1988.Google Scholar
- DeJong RN. The neurologic examination. New York: Hoeber Medical Division, Harper & Row; 1978.Google Scholar
- Herrick CJ. The brain of the tiger salamander. Chicago: University of Chicago Press; 1948.Google Scholar