,"58 



THE CRANIAL NERVES. 



Fig. 179. 



which runs downward and forward, penetrates the larynx by an open- 

 ing in the side of the thyro-hyoid membrane, and is distributed to the 

 mucous membrane covering the epiglottis and lining the interior of the 

 laryngeal cavity. This is the main portion of the nerve, and it is sensi- 

 tive in character; providing for the peculiar sensibility of the glottis and' 

 epiglottis and for that of the inner surface of the larynx in general. 

 The nerve gives off, however, a small muscular branch which terminates 

 in the inferior constrictor of the pharynx and in the crico-thyroid mus- 

 cle of the larynx. It also supplies several filaments, which 'unite with 

 others coming from the great sympathetic, to form the laryngeal plexus ; 

 and by this plexus the superior laryngeal branch of the pneumogastric 

 furnishes filaments to the upper cardiac nerves of the cervical portion 



of the sympathetic. Other filaments 

 pass off from the trunk of the pneumo- 

 gastric while passing down the neck, 

 which also join the cardiac branches 

 of the sympathetic, and which in some 

 instances, according to Cru veilhier, pass 

 directly downward, to unite with the 

 cardiac plexus beneath the concavity 

 of the arch of the aorta. 



The next branch is the inferior 

 laryngeal nerve, which separates from 

 the trunk of the pneumogastric after 

 entering the cavity of the chest, curves 

 round the subclavian artery on the 

 right side and the arch of the aorta on 

 the left, and ascends, in the groove 

 between the trachea and oesophagus, 

 to the larynx, giving off branches to 

 the oesophagus and the inferior con- 

 strictor muscle of the pharynx. In 

 the larynx it is distributed to all the 

 muscles of this organ, excepting the 

 crico-thyroid, which is supplied by the 

 superior laryngeal. The larynx is 

 therefore supplied by two different 

 branches of the pneumogastric nerve, 

 which are mainly distinct from each 

 other in their properties and functions. 

 The superior laryngeal branch is for 

 the most part a sensitive nerve, sup- 



ORIGIN AND COURSE OF THE G-LOSSOPHARYNGE A L, PNETTMOGASTRIC, AND 

 SPINAL ACCESSORY NERVES. 1. Facial nerve. 2. Glossopharyngeal. 3. Pneumogastric. 

 4. Spinal accessory. 5. Hypoglossal. 6. External (muscular) branch of the spinal accessory. 

 7. Superior laryngeal branch of the pneumot-astric. 8. Pharyngeal plexus. 9. Laryngeal 

 plexus and uppercardiac branches of the pneumogastric. 10. Tympanic plexus, from a branch 

 of the glossopharyngeal. (Hirschfeld.) 



