STUDIES ON THE SYMPATHETIC NERVOUS SYSTEM 309 
The craniosacral autonomic system is that division of the 
autonomic system, the preganglionic fibers of which make their 
exit from the cerebrospinal axis through the III, VII, IX, X, 
and XI cranial nerves and the IJ, III, and IV sacral nerves. 
The preganglionic neurones are those, the cell bodies of which 
lie in the brain or spinal cord and whose axons run through the 
cerebrospinal nerves to enter the sympathetic system and end 
in its ganglia. The autonomic nervous system therefore includes 
certain cells in the brain and spinal cord and certain fibers in the 
cerebrospinal nerves and is not contained exclusively in the 
sympathetic system. The postganglionic neurones are those 
whose cellbodies lie in the sympathetic ganglia and whose axons 
run to end on cardiae or smooth muscle or in glandular tissue. 
In order to show how these terms will aid in the presentation 
cf the facts of visceral innervation, we may give a few examples. 
While some points are still obscure, the outlines given below are 
as nearly correct as our present knowledge enables us to make 
them. They are given not as an ultimate statement of fact, but 
as an illustration of the sort of information which we should strive 
to perfect. 
IMPORTANT FUNCTIONAL PATHS IN THE AUTONOMIC SYSTEM 
1. Paths for the efferent innervation of the eye. 
a. Ocular craniosacral pathway. 
Preganglionic neurones. Cells in the oculomotor nu- 
cleus, fibers by way of the III cranial nerve to end in the 
ciliary ganglion. 
Postganglionic neurones. Cells in the ciliary ganglion, 
fibers by way of the short ciliary nerves to the ciliary 
muscle and the circular fibers of the iris. 
Function—accommodation and contraction of the 
pupil. 
b. Ocular thoracicolumbar pathway. 
Preganglionic neurones. Cells in the intermedio- 
lateral column of the spinal cord, fibers by way of the 
upper white rami and sympathetic trunk to end in the 
superior cervical ganglion. 
