The Viscekal ok Splanchnic Division 99 



heart and lungs through the stellate ganglion. The lower thoracic and 

 upper three or four lumbar spinal roots supply the abdominal viscera : the 

 stomach, small intestine, kidneys, spleen, by way principally of the ' col- 

 lateral ' ganglia ; the colon, bladder, and genital organs by way of the 

 ' pelvic ' ganglia. The arm is innervated from the thoracic roots from the 

 fourth to the tenth, through the ' stellate ' ganglion ; and the leg is sup- 

 plied from the roots from the thoracic dorsal to the third lumbar, through 

 lateral ganglia of the lumbar and sacral regions. 



The functions of the ' sympathetic ' nerve are, in brief : to cause con- 

 traction and relaxation of the muscular coats of the blood vessels (which 

 functions are called vasoconstrictor and vaso=di!ator respectively) ; 

 to cause contraction and relaxation of the smooth muscle of various other 

 viscera (motor and inhibitory functions) ; to stimulate secretion of sali- 

 vary and sweat gland ; and to accelerate the heart beat. 



2. Visceral neurons of the cranial, vagus, and sacral divisions. 



The third, seventh, ninth, tenth and eleventh cranial nerves contain 

 visceral fibers, as well as somatic fibers. The visceral fibers in the third 

 nerve are axons which run to the ' ciliary ' ganglion in the orbit (eye 

 socket) from which the impulses are relayed to the ciliary muscle (the 

 muscle of accommodation) and the sphincter pupillae (muscle of the iris). 

 The visceral fibers in the facial (seventh) nerve are efferent, but are den- 

 drites of cell bodies lying in several cranial ganglia (' submaxillary ', 

 ' spheno-palatine ' ganglia, etc.), differing thus from the typical arrange- 

 ment of the efferent neurons conducting from the cord and brain. The 

 fibres relaying from these ganglia terminate in the sublingual and sub- 

 maxillary glands (salivary), the blood vessels of the tongue and the 

 glands of various parts of the mucous membrane of the nose and mouth 

 cavities. 



The visceral fibers in the glossopharyngeal (ninth) nerve are axons and 

 dendrites of cell-bodies in the medulla, and run to the otic ganglion, 

 whence the efferent fibers are relayed by post-ganglionic axons to the 

 parotid gland (salivary). Possibly there are ninth-nerve fibers running 

 to blood vessels in the back part of the tongue. The tenth nerve, with 

 some of the fibers derived from the roots of the eleventh, together form 

 the vagus, or pneumogastric nerve, which, like the ninth nerve, is en- 

 tirely visceral, and both afferent and efferent. The afferent fibers are 

 dendrites derived from the ' jugular ' ganglion, and the ganglion ' trunci 

 vagi ' (vagus trunk ganglion) ; the efferent fibers are (like those of the 

 seventh nerve) dendrites of cell-bodies in the ganglia located in the vis- 

 cera the nerve supplies. The efferent distribution of the vagus is to the 

 smooth muscles of the gullet, stomach, small intestine, and bronchial 



