ANTERIOR ASPECT OF HEAD AND NECK. 



men; it communicates with the superior cervical ganglion of 

 the sympathetic, and the auricular branch and, sometimes, 

 ganglion of the root of the vagus. Its tympanic branch (Ja- 

 cobson's nerve) runs, in a canal between the carotid canal and 

 jugular foramen, to the tympanum and forms a plexus (tym- 

 panic) there with the small deep petrosal ; the plexus supplies 

 the tympanic mucosa; the fibres then reunite and join a branch 

 of the geniculate ganglion, forming the small superficial pe- 

 trosal which runs to the otic ganglion. [689] 



Vagus. Emerging from the jugular foramen, and develop- 

 ing two ganglia, this descends in the carotid sheath, lying be- 

 tween and behind the vessels, to the thorax. Branches in the 

 Neck : The superior and inferior cardiac descend to the thorax. 

 The right inferior laryngeal arises over the subclavian artery, 

 winds around this, then ascends behind the common carotid 

 and inferior thyroid arteries, enters the larynx under the In- 

 ferior constrictor and supplies all the laryngeal muscles except 

 the Crico- thyroid. Its other branches are cardiac; commu- 

 nicating, to the inferior cervical ganglion of the sympathetic; 

 and muscular, to the trachea, oesophagus, and Inferior con- 

 strictor. On the left side the nerve arises in the thorax, as- 

 cends between the trachea and oesophagus to the neck, and 

 then follows the same course. [690] 



The ganglion of the root lies in the jugular foramen and is 

 small and spherical. It communicates with the spinal acces- 

 sory, superior cervical ganglion of the sympathetic and, some- 

 times, petrous ganglion of the glosso-pharyngeal. Branches: 

 The meningeal supplies the dura of the posterior fossa. The 

 auricular (Arnold's nerve) ascends in a fissure, between the 

 jugular and stylo-mastoid foramina, to supply the external 

 auditory meatus and back of the pinna. It communicates 

 with the tympanic branch of the glosso-pharyngeal near its 

 origin, with the facial in the aqueduct, and with the posterior 

 auricular (facial). [692] 



The ganglion of the trunk lies just below the preceding and 



[75] 



