THE AUTONOMIC NERVE SYSTEM 661 



which pass for the most part to neighboring structures, though from the 

 lower lumbar and sacral ganglia branches pass to viscera in the lower ab- 

 dominal and pelvic regions. 



In accordance with the law of distribution and relations of the fibers of 

 the sympathetic ganglia to peripheral organs, it can be assumed that to what- 

 ever organ the visceral branches are distributed they too ultimately terminate 

 in the non-striated muscle-cells of the walls of the blood-vessels and the walls 

 of hollow viscera, and in some situations in the epithelium of glands as well. 



The Pre-vertebral Ganglia. The pre-vertebral ganglia are located in 

 the abdominal cavity. 



The semilunar, the renal, and the superior mesenteric are situated in the 

 neighborhood of the celiac axis and on a level with the adrenal bodies. These 

 ganglia give off an enormous number of visceral branches which interlace in 

 a very intricate manner forming what is known as the solar plexus. Sub- 

 divisions of this plexus, taking their names from the regions to which they 

 are distributed, are known as the gastric, renal, adrenal, splenic, hepatic and 

 superior mesenteric. The terminals of the fibers composing these plexuses 

 are distributed to the non-striated muscle-fibers of blood-vessels of the stom- 

 ach, kidney, adrenal body, liver, and small intestine; to the muscle-walls of 

 the stomach, the small intestine, the walls of the gall-bladder, as well as the 

 sphincter muscles surrounding the pyloric and the ileo-colic orifices. 



The inferior mesenteric ganglion situated close to the origin of the inferior 

 mesenteric artery gives off visceral fibers, which also interlace with other 

 fibers to form. the hypogastric plexus, from which fibers pass to the muscle- 

 walls of the colon, bladder, uterus, vagina and to the blood-vessels of the 

 pelvic viscera. 



The Peripheral Ganglia. The peripheral ganglia, as previously stated, 

 are in more or less close relation with tissues and organs in different regions 

 of the body. Among the members of this group may be mentioned the 

 ciliary or ophthalmic, the sphenopalatine, the otic and the submaxillary 

 ganglia; the ganglia in the walls of the heart, in the walls of the respiratory 

 organs, in the walls of the stomach, and intestines and the ganglia at the 

 base of the bladder (the pelvic ganglia). 



The ganglia situated in the head are usually described in connection with 

 and as constituent parts of the cranial nerve system. They, however, bear 

 the same relation to the cranial that the vertebral and pre-vertebral ganglia 

 bear to the spinal nerves. They consist of ganglion cells from which post- 

 ganglionic fibers pass to glands, blood-vessels, and viscera. Motor and sensory 

 nerves pass through one or more ganglia, though they have no anatomic 

 connection with them. In their structure, distribution and functions they 

 closely resemble the collateral ganglia. 



1. The ciliary or ophthalmic ganglion is situated in the orbital cavity posterior 



to the eyeball. It is small in size, gray in color, and consists of a con- 

 nective-tissue stroma containing nerve-cells. From these cells post- 

 ganglionic fibers emerge which, after a short course forward, penetrate 

 the eyeball and terminate in the circular fibers of the iris and the ciliary 

 muscle. 



2. The spheno-palatine ganglion is situated in the spheno-maxillary fossa. 



Its nerve-cells send non-medullated post-ganglionic fibers to the blood- 

 vessels and glands of the mucous membrane of the nasal and oral regions. 



