front matter 1

ABTop View Side View

CD

EF

White matter

outlined

Gray matter

outlined

"Domes" of gray matter

in the dorsal horn

Central canal

(defines midlline)

Medial motor columns (split)

Autonomic

motor columns

Posterior cap of motor column 4

in cervical region

11

11

The recessed

dorsal midline

Figure 31. The thoracic region in specimen Y68-65 (GW14, CR 108 mm). The individual sections (1101-1741) in this model are diagrammed in Figure
24. The reconstructed length is 22.4 mm after fi xation. Panels A, C, and E show the model from the top front, panels B, D, and F from the upper
right side. Panels A and B show both the white matter (outlined transparent envelope) and gray matter (inner transparent envelope) around the central
canal (gray-white solid) and the medial motor columns ( 1 , cyan), autonomic motor columns (green), and the posterior cap of motor column 4 (yellow-
brown) from the cervical region that is present only in the fi rst section (1101). Panels C and D show only the gray matter (outlined transparent envelope)
around the central canal and the motor columns. Panels E and F show the central canal and the motor columns alone. This region of the spinal cord is
distinguished from other regions by having a bifurcated motor column 1 that probably innervates axial muscles associated with the thoracic vertebrae,
rib cage, and dorsal abdominal wall. The autonomic motor columns in the lateral horn are prominent and innervate neurons in the sympathetic ganglia.

FIGURE 31 GW14, CR 108 mm, Y68-65