THE AUTONOMIC NERVOUS SYSTEM 473 



to the tongue, the submaxillary and sublingual glands, and secretory fibres 

 to these glands. 



The cell stations of these nerves lie peripherally, those of the sublingual 

 gland in the so-called submaxillary ganglion ; those of the submaxillary 

 gland in the hilus of this organ. It is probable that the seventh sends also 

 pre-ganglionic visceral fibres to the spheno-palatine ganglion, whence a fresh 

 relay of fibres post-ganglionic run with the branches of the fifth nerve, 

 to supply secretory fibres and possibly vaso-dilator fibres to the mucous 

 membrane of the nose, soft palate, and upper part of the pharynx. The 

 glossopharyngeal or ninth nerve sends fibres, which evoke secretion as well as 

 vaso-dilatation in the parotid gland, via the otic ganglion. Probably also 

 dilator fibres leave this nerve to supply vessels at the back of the tongue. 



THE VAGUS 



The efferent visceral fibres of the tenth and eleventh nerves arise in the 

 same column of cells as the two nerves just considered. Most of the fibres 

 run in the vagus. They include motor fibres to the oesophagus, stomach, and 

 small intestines as far as the ileocolic sphincter ; inhibitory fibres .to the 

 heart ; motor fibres to the unstriated muscles of the bronchi ; and secretory 

 fibres to the gastric glands. The cell stations of these fibres are apparently 

 situated peripherally, the jugular ganglion and the ganglion of the trunk 

 of the vagus being in all likelihood responsible only for the afferent fibres in 

 this nerve. Nicotine therefore abolishes any effect of stimulating the vagus 

 in the neck, though inhibition of the heart can still be produced on excitation 

 of the post-ganglionic fibres arising from the cells in the sinus venosus. 



SACRAL AUTONOMIC FIBRES 



These all run in the pelvic visceral nerve, also called nervus erigens. 

 This nerve is connected with a collection of ganglia lying in the hypogastiic 

 plexus at the base of the bladder. It has the following functions : 



Dilator to vessels of the penis (hence its name of nervus erigens). 



Motor to bladder, colon, and rectum. 



Inhibitory to sphincter muscle of bladder. 



Inhibitory to retractor penis. 



It will be observed that in many cases the viscera get their nerve-supply 

 from both sets of visceral nerves, and that in such cases the two sets of 

 nerves are antagonistic in function. It- is impossible however to draw a 

 sharp line between the functions of the two sets, since the same nerve may be 

 motor for one set of muscular fibres and inhibitory for another set in the 

 same viscus. Thus the colonic branches of the inferior mesenteric ganglion 

 are motor (constrictor) for the blood vessels and inhibitory for the muscular 

 walls of the colon. While the sympathetic nerve supply is inhibitory for 

 nearly the whole intestinal muscles, it produces strong contraction of the 

 band of muscle forming the ileocolic sphincter. In the bladder there 

 is no doubt that the sympathetic supply includes both inhibitory and 

 motor fibres, the predominating effect on excitation of the nerve varying 

 from one species of animal to another.. 



