CERVICAL GANGLIA. 485 



carotid plexus. They also form frequently a small gangliform swelling 

 upon the under part of the artery, which is called the carotid ganglion. 

 The latter, however, is not constant. The continuation of the carotid 

 plexus onwards with the artery by the side of the sella turcica, 

 is called the cavernous plexus. 



The carotid plexus is the centre of communication between all the 

 cranial ganglia ; and being derived from the superior cervical ganglion, 

 between the cranial ganglia and those of the trunk, it also com- 

 municates with the greater part of the cerebral nerves, and distributes 

 filaments with each of the branches of the internal carotid, which 

 accompany those branches in all their ramifications. 



Thus, the Ganglion ofRibes is formed by the union of the filaments 

 which accompany the anterior cerebral arteries, and which meet on 

 the anterior communicating artery. The ciliary ganglion communi- 

 cates with the plexus by means of the long branch which is sent back 

 to join it in the cavernous sinus. The spheno-palatine, and with it 

 the naso-palatine ganglion, joins the plexus by means of the carotid 

 branch of the Vidian. The submaxillary ganglion is brought into 

 connection with it by means of the otic ganglion, and the otic ganglion 

 by means of the tympanic nerve and the Vidian. 



It communicates with the third nerve in the cavernous sinus, and 

 through the ciliary ganglion ; frequently with the fourth in the 

 formation of the nerve of the tentorium ; with the Casserian ganglion ; 

 with the ophthalmic division of the fifth in the cavernous sinus, and by 

 means of the ciliary ganglion ; with the superior maxillary, through 

 the spheno-palatine ganglion ; and with the inferior maxillary, through 

 the otic ganglion. It sends two branches directly to the sixth nerve, 

 which unite* with it as it crosses the cavernous sinus ; it communi- 

 cates with the facial and auditory nerves, through the medium of the 

 petrosal branch of the Vidian ; and with the glosso-pharyngeal by 

 means of two filaments to the tympanic nerve. 



CERVICAL GANGLIA. 



The Superior cervical ganglion is long and fusiform, of a greyish 

 colour, smooth, and of considerable thickness, extending from within 

 an inch of the carotid foramen in the petrous bone to opposite the 

 lower border of the third cervical vertebra. It is in relation in front 

 with the sheath of the internal carotid artery and internal jugular 

 vein ; and behind with the rectus anticus major muscle. 



Its branches, like those of all the sympathetic ganglia in the trunk, 

 are divisible into superior, inferior, external, and internal; to which 

 may be added, as proper to this ganglion, anterior. 



The superior (carotid nerve) is a single branch which ascends by 



* Panizza, in his " Experimental Researches on the Nerves," denies this 

 communication, and states very vagaely that " they are merely lost and en- 

 twined around it." Edinburgh Medical and Surgical Journal, January 1836. 



