PAR VAGUM. 501 



from the ganglion of Meckel. While situated in the jugular 

 fossa the pneumogastric exhibits two gangliform enlargements ; 

 one, the Superior, called the jugular ganglion of Miiller, the 

 second, the inferior, named the ganglion of Andersch, or the 

 petrous ganglion. From the latter passes off the tympanic nerve 

 (Jacobsori's nerve) to supply the tympanic cavity as described in 

 the account of the ear. 



The Par Vagum 



As it passes through the anterior part of the foramen lace- 

 rum presents a small rounded ganglion embraced by the dura 

 mater which forms a canal about the nerve. Shortly after 

 it has passed through the foramen lacerum, it forms a 

 ganglionic enlargement of about an inch in length, from which 

 a number of white nerves proceed, anastomosing with the 

 surrounding trunks. 



As it descends, it adheres to the superior ganglion of the 

 intercostal, and also to the ninth pair. It proceeds behind 

 and on the outside of the carotid, and is contained in the 

 same sheath of cellular membrane which encloses that artery 

 and the internal jugular vein. Each of these nerves, soon after 

 it leaves the cranium, gives a twig to the glosso-pharyngeal ; 

 soon after that it sends off a branch called the Pharyngeal, 

 which unite to one from the accessory nerve, and to one or 

 more from the glosso-pharyngeal, and proceeds to the middle 

 constrictor of the pharynx, when it expands into ramifications 

 that form a plexus from which proceed a number of small twigs 

 that go to the larynx, and some that pass down on the common 

 carotid artery. 



It then sends off, downward and forward, the Superior 

 Laryngeal nerve, which continues in that direction behind 

 the carotid artery, and divides into an external and internal 

 branch. 



The Internal Branch, which is the largest, proceeds be- 

 tween the os hyoides and the thyroid cartilage ; and divides into 

 numerous ramifications which are distributed to the arytenoid 



