THE VAGUS NERVE. 



1265 



the posterior part of the dorsum of the tongue, the glosso- epiglottic and pharyngo- 

 epiglottic folds and the lingual surface of the epiglottis. The smaller anterior branch 

 supplies the mucous membrane of the side of the tongue half way to the tip. 



Fig. 1076. 



Digastric, post. 

 belly in part 



I. cervical nerve 

 Spinal accessory nerve 

 Occipitalis minor nerve 



Sup. cerv. gangl. of sympathetic 



Br. from II. cerv. nerve 



to sp. access. 



III. cervical nerve 



Communicans hypoglossi 



Greatauric. and superf. cerv. nerves 



IV. cervical nerve 



External 

 pterygoid 

 ;tr^ Ling. br.V. nerve 



•j.;4- \ Chorda 



"'" j tympani nerve 



Int. pterygoid 

 Edge of oral mu- 

 cous membrane 

 osso-pharyngeal 



ental nerve 

 nf. dental nerve, 

 distal portion 

 Sublingual gland 



Submaxillary gangl. 

 Stylo-pharyngeui 



Middle cervical ganglion of sympathetic 



(the cord connecting it with superior gangl. is also seen 



Deep dissection of neck showing ninth, tenth, eleventh and twelfth cranial nerves and their branches. 



Variation. — Instances are recorded in which the mylo-hyoid nerve was absent and a 

 branch of the glosso-pharyngeal supplied the mylo-hyoid muscle and the anterior belly of the 

 digastric, the innervating fibres being, probably, aberrant filaments of the trigeminus. 



THE VAGUS NERVE. 



The tenth, vagus or pneumogastric ner\'e (n. vagus) is the longest and most 

 widely distributed of the cranial series. Starting in the cranium, it passes through 

 the neck, thorax and upper part of the abdomen before breaking up into its terminal 

 branches. In addition to certain filaments concerned with special functions, distrib- 

 uted to the heart and abdominal viscera, it contains both motor and sensory fibres. 

 Some of. the motor constituents of the nerve arise from its own origin, but the major- 

 ity perhaps are contributions of the accessoriiis vagi, the so-called accessory part of 

 the spinal accessory nerve. The vagus supplies motor fibres to the muscles of the 

 soft palate (with the exception of the tensor palati and, probably, partly the levator 

 palati and azygos uvulee), pharynx, oesophagus, stomach, and intestine (with the 

 exception of the rectum), and to those of the larynx, trachea, and bronchi and their 

 subdivisions. It distributes sensory fibres to the dura mater, external ear, pharynx, 

 oesophagus, stomach, larynx, trachea, bronchi and subdivisions and pericardium. 



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