The view of the nature of this filament here advanced is, however, not universally admitted. Cruveilhier objects to it because the cranial branch of the Vidian nerve appears to him to resemble in all respects the carotidean : this, however, cannot be considered a valid objec tion, it can only prove that one branch may be as much allied to the ganglionic system as the other, but the validity of the assertion may be questioned ; however it may be in man, the characters of the two branches in the larger quadrupeds, the horse e. g. are sufficiently distinct, the cranial branch being of a pure white colour, and the carotidean having a gan glionic enlargement upon it at its junction with the cranial.
NThile traversing the pterygoid canal, soon after it has entered that canal, and in some cases even before, the posterior branch of the gan glion gives off from its inner side two or three filaments, denominated by the elder Meckel posterior superior nasal: these enter the poste rior superior part of the nostril, in one case by passing through the spheno-palatine foramen, in the other by perforating the inner wall of the pterygoid canal, and are distributed to the posterior part of the lateral wall of the nostril, to the root of the septum, to the sphenoidal sinus and to the lateral wall of the pharynx in the vicinity of the orifice of the Eustachian tube. These branches frequently arise from the ganglion itself by a single filament, de nominated by Bock the pharyngeal nerve, and represented by Arnold among the internal branches of the ganglion : it divides into fila ments distributed to the several parts men tioned.
After the junction of the sympathetic fila ment, the posterior branch is continued through the fibrous structure already mentioned, ex ternal to the internal carotid artery, and thus enters the cranium. It then passes out ward, backward, and upward, upon the ante rior surface of the petrous bone, beneath the third division of the fifth, very near its attachment to the Gasserian ganglion, and enclosed in the dura mater : it is at the same time lodged in a channel upon the sur face of the bone. It is stated by Cloquet that it here sends into the cavity of the tympanum by two canals, the orifices of which are to be seen in the channel one above the other, two filaments of extreme delicacy, which go to anastomose together upon the promontory, and to communicate with a filament of the supe rior cervical ganglion, and with the glosso pharyngeal nerve. According to Hirzel,* this connection between the superficial branch of the Vidian and the tympanic branch of the glosso-pharyngeal nerve on the nerve of Jacob son, takes place in the vicinity of the junction of the former with the facial nerve. Accord
ing to Arnold,- the superficial branch of the Vidian nerve is, as proved by the researches of others and his own, not simple, but composed of two or of several filaments, and is accom panied by one or more very delicate filaments from the carotid plexus. In one instance he found the petrous nerve composed of four filaments on the right, and three on the left. The existence of several distinct filaments in the Vidian nerve may be easily observed in the larger animals. It pursues the course men tioned, until it has reached the hiatus Fallopii, through which it is transmitted to the aqueduct of Fallopius, where it meets and becomes in timately connected with the facial portio dura nerve. At their junction the facial nerve pre sents a gangliform swelling, from which two very delicate filaments proceed to the auditory nerve. I From the time that the posterior branch of the ganglion enters the cranium until it has joined the facial nerve, it is called the cranial or superficial petrous branch of the Vidian nerve ; by Arnold petrosus superficialis major in contradistinction to another nervous filament, which connects his ' otic' ganglion to the tym panic branch of the glosso-pharyngeal nerve ; but the application of either of these epithets would be rendered unnecessary by ceasing to consider the filament by which the posterior branch of the ganglion is connected to the sympathetic, a branch of the former.
The posterior branch is also known by other names, viz. the recurrent, the ptcryguid, the Vidian, the auastomotie, or sympathie.
3. The next branch or branches of the su perior maxillary nerve are the posterior supe rior dental. These arise from the nerve in front of the internal maxillary artery, between it and the back of the antrum, and are sepa rated from the artery by the spheno-palatine ; they are very irregular as to their number and precise place of origin ; at times there is hut one branch, at others there are two or three : they are distributed to the buccinator muscle and the mucous membrane of the posterior lateral part of the mouth, to the roots of the posterior teeth, the membrane of the maxil lary antrum, and the gum of the upper jaw. When but one branch is present, its sub divisions supply the place of the others. It descends into the fossa, behind the superior maxillary bone, and before the internal maxil lary artery, and after a certain way divides into two branches or sets of branches, posterior and anterior.