340 THE SPINAL CORD. 



or base. From it the anterior roots of the spinal nerves rise; and, 

 together with the anterior root-fibers, it separates from each other 

 the anterior and lateral white columns of the cord. 



Cells of the Anterior Columna (Figs. 102 and 103). The gray 

 matter of the spinal cord contains multipolar neurones of the 

 Golgi and Deiters types. The Golgi cells ramify richly in the 

 gray matter about the cell-bodies, and, both their axones and 

 dendrites terminate in relation with other neurones in the adjacent 

 gray substance. The long axones of the Deiters cells either enter 

 into the anterior roots (radices anterior), and the neurones are 

 called radicular cells, or they enter into a longitudinal tract or 

 strand of fibers, and the neurones are named strand-cells (Cunning- 

 ham). The dendrites of the Deiters cells arborize in both the 

 gray and white substance. The cell-bodies in the anterior columna 

 are large and vesicular in character. They are motor or efferent 

 hi function, and their axones form, in great part, the anterior roots 

 of the spinal nerves. Together with the neurones of the genetic 

 nuclei of cerebral nerves, these of the anterior columna constitute 

 the lower segment motor neurones. 



Two chief columns of cell-bodies are located in the anterior 

 columna, the medial column and the lateral column (Figs. 

 102 and 103). The former is continuous throughout the cord 

 with the exception of the fifth lumbar and the first sacral segments 

 (Bruce- Cunningham); while the lateral column is found only 

 in the cervical and lumbar enlargements. The medial column 

 of cells shows a double group in sections of the lower three cer- 

 vical, all the thoracic and the first lumbar segments of the cord. 

 These subgroups are called the ventro-medial and the dorso- 

 medial cells. Only the ventro-medial group is present above the 

 sixth cervical segment and below the first lumbar segment. The 

 dendrites of the cell-bodies in the medial column arborize in the 

 gray substance of the same columna, in the adjacent white matter 

 of the anterior column of the cord and, to some extent, in the 

 opposite anterior columna, having passed through the white an- 

 terior commissure; the axones of these medial cell-bodies enter 

 very largely into the anterior roots of the spinal nerves on the 

 same side; but a certain number probably run through the white 



