OTIC GANGLION CAROTID PLEXUS. 429 



which communicate with the sympathetic filaments ramifying upon 

 the facial artery. It is associated with the carotid plexus, and 

 the other cranial ganglia, by means of the petrosal branch of the 

 Vidian. 



6. The OTIC GANGLION (Arnold's)* is a small red body, resting 

 against the inner surface of the inferior maxillary nerve, imme- 

 diately below the foramen ovale; it is in relation externally with the 

 trunk of the inferior maxillary nerve, just at the point of union of 

 the motor root; internally it rests against the cartilage of the Eusta- 

 chian tube and tensor palati muscle ; and posteriorly it is in con- 

 tact with the arteria meningea magna. It is closely adherent to 

 the internal pterygoid nerve, and appears like a swelling upon that 

 branch. 



The branches of the otic ganglion are seven in number ; two of 

 distribution, and five of communication. 



The branches of distribution are, 1, a small filament to the 

 tensor tympani muscle ; and, 2, one to the tensor palati muscle. 



The branches of communication are, 1, two or three small 

 branches to the motor root of the inferior maxillary nerve ; 2, two 

 branches to the auricular nerve : 3, a filament to the facial nerve ; 

 4, a long filament, the nervous petrosus superficialis minor to com- 

 municate with the tympanic nerve (Jacobson's) in the tympanum ; 

 and, 5, one or two small branches which join the sympathetic fila- 

 ments of the arteria meningea media artery. 



CAROTID PLEXUS. The ascending branch of the superior cervical 

 ganglion enters the carotid canal with the internal carotid artery, 

 and divides into two branches, which form several loops of commu- 

 nication with each other around the artery. This constitutes the 

 carotid plexus. They also form frequently a small gangliform swell- 

 ing upon the under part of the artery, which is called the carotid 

 ganglion. The latter, however, is not constant ; and, as it performs 

 no special function, we do not include it amongst the cranial gan- 

 glia of the sympathetic. 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 

 communicates 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 of Ribes is formed by the union of the fila- 

 ments which accompany the anterior cerebral arteries, and which 

 meet on the anterior communicating artery. The ciliary ganglion 

 communicates with the plexus by means of the long branch which 

 is sent back to join it in the cavernous sinus. The spheno-palatine, 



* Frederick Arnold, " Dissertatio Inauguralis de Parte Cephalica Nervi Sympa- 

 thetic!." Heidelterg, 1826 ; and "Uebcr den Ohrknoten," 1828. 



