Page 343 - Atlas of Histology with Functional Correlations

FIGURE 9.5 | Spinal Cord: Midcervical Region

(Transverse Section)

A cross section of the spinal cord was prepared with the silver impregnation
technique to illustrate the white matter and the gray matter. After staining, the

dark brown, outer white matter (3) and the light-staining, inner gray matter (4,
14) are visible. The white matter (3) consists primarily of ascending and
descending myelinated nerve fibers or axons. By contrast, the gray matter
contains neurons and interneurons. The gray matter also exhibits a symmetrical

H-shape, with the two sides connected across the midline of the spinal cord by
the gray commissure (15). In the center of the gray commissure is the central
canal (16) of the spinal cord.

The anterior horns (6) of the gray matter are more prominent than the

posterior horns (2, 13) and contain the cell bodies of the large motor neurons
(7, 17). Some axons (8, 20) from these motor neurons cross the white matter and
exit from the spinal cord as anterior roots (9, 21) of the peripheral nerves. The
posterior horns (2, 13) are the sensory areas and contain cell bodies of smaller
neurons.

The spinal cord is surrounded by connective tissue meninges, consisting of
an outer dura mater, a middle arachnoid mater (5), and an inner pia mater
(18). The spinal cord is also partially divided into right and left halves by a
narrow, posterior (dorsal) groove—the posterior median sulcus (10)—and a

deep, anterior (ventral) cleft—the anterior median fissure (19). In this
illustration, pia mater (18) is best seen in the anterior median fissure (19).

Between the posterior median sulcus (10) and the posterior horns (2, 13) of
the gray matter are the posterior columns of the white matter. In the midcervical

region of the spinal cord, each dorsal column is subdivided into two fascicles,
the posteromedial column—the fasciculus gracilis (11)—and the posterolateral
column—the fasciculus cuneatus (1, 12).

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