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INTRODUCTION

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The spinal cord is made of both gray and white matter. Gray matter consists of neurons, neuronal processes, and neuroglia. It is butterfly or H-shaped. White matter surrounds gray matter and is made up of neuronal processes (myelinated and unmyelinated), neuroglia, and blood vessels. The proportion of gray to white matter varies at different levels of the spinal cord. The ratio of gray to white matter is greatest at the cervical and lumbar regions.

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GRAY MATTER

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Gray matter can be categorized into columns (or horns) and laminae (Figure 122-1). The columns include a ventral (or anterior) column, which contains motor neurons, and an intermediolateral gray column, which contains preganglionic cells for the autonomic nervous system. The intermediolateral gray column contains preganglionic sympathetic neurons from T1-L2 and contains parasympathetic neurons at S2-S4. In addition, a dorsal (or posterior) gray column is involved in sensory processing. Lissauer tract lies in this area and is part of the pain pathway. The anterior and posterior horns are united by a gray commissure that contains a small, central canal.

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FIGURE 122-1

Laminae of spinal cord gray matter. (Reproduced with permission from Waxman SG, Clinical Neuroanatomy, 27th ed. McGraw-Hill Companies, Inc. 2013. All rights reserved.)

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There are 10 laminae (layers of nerve cells), also known as Rexed laminae that make up the gray matter. Each of these laminae is involved in sensory or motor pathways (Table 122-1).

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Table Graphic Jump Location
TABLE 122-1Laminae (Gray Matter)
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WHITE MATTER

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The white matter is divided into columns, including the dorsal, lateral, and ventral columns (Figure 122-2). Each column contains tracts, which are groups of nerve fibers that have similar destinations in relaying sensory and motor information. For instance, the dorsal column can be divided into a medial tract (fasciculus gracilis) and a lateral ...

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