66 2 TEXT-BOOK OF PHYSIOLOGY 



3. The otic ganglion is situated just below the foramen ovale and internal 



to the third division of the fifth nerve. The cells give origin to post- 

 ganglionic fibers which pass to the parotid gland by way of the auriculo- 

 temporal division of the fifth nerve, and to the blood-vessels of the 

 mucous membrane of the lower lip, cheek, and gums. 

 Motor fibers from the small or motor root of the fifth nerve pass 

 through this ganglion to the tensor tympani muscle. 



4. The submaxillary ganglion is situated close to the corresponding gland. 



The post-ganglionic fibers to the blood-vessels and gland-cells. 



5. The cardiac ganglia are situated in different regions in the walls of the 



heart; their visceral branches are distributed directly to the heart muscle- 

 cells. 



6. The pelvic ganglia are situated close to the base of the bladder; their 



visceral branches are distributed to the blood-vessels of the generative 

 organs and to the muscle- walls of the bladder, rectum, etc. 

 From the distribution of the branches emerging from all the different 

 groups of ganglia there is every reason to believe that they are in some way 

 associated with vaso-augmentor and vaso-inhibitor, viscero-augmentor and 

 viscero-inhibitor, secreto-motor and secreto-inhibitor, and pilo-motor phenom- 

 ena. 



THE ANATOMIC RELATION OF THE CENTRAL NERVE SYSTEM TO THE 



SYMPATHETIC GANGLIA 



The central nerve system is associated anatomically and physiologically 

 with the sympathetic ganglia through the intermediation of fine medullated 

 nerve-fibers, the pre-ganglionic, which have their origin in nerve-cells situated 

 in four different regions, viz. : 



1. The Mid-brain Region. The pre-ganglionic nerve-fibers that leave the 



brain in this region arise from groups of nerve-cells situated high up in 

 the gray matter beneath the aqueduct of Sylvius just where it widens 

 to form the cavity of the third ventricle. From this origin they enter 

 the trunk of the oculo-motor nerve and in association with it enter the 

 orbit cavity. In this situation these pre-ganglionic fibers leave the 

 oculo-motor nerve and enter the ciliary or ophthalmic ganglion around 

 the nerve-cells of which their terminal branches arborize. The gray 

 post-ganglionic fibers arising in the gray cells of this ganglion enter the 

 eyeball and are ultimately distributed to the sphincter muscle of the 

 iris and to the ciliary muscle. 



2. The Bulbar Region. The pre-ganglionic fibers that leave the brain in 



this region arise from nerve-cells situated in the gray matter beneath the 

 floor of the fourth ventricle a little above and below the calamus scrip- 

 torius. These fibers leave this region by three routes, viz.: in the 

 trunks of (i) the pars intermedia or nerve of Wrisberg, (2) the glosso- 

 pharyngeal and (3) the vagus. 



The Nerve of Wrisberg. The pre-ganglionic fibers that leave by this 

 nerve enter the facial nerve and subsequently pass in part by way 

 of the great superficial petrosal nerve to the spheno-palatine gang- 

 lion, and in part by way of the chorda tympani nerve to the sub- 

 maxillary ganglion, around the nerve-cells of which their terminal 

 branches arborize. The gray post-ganglionic fibers that arise in the 



