The branches connected with the septum are two, a short and a long one ; they both pass across the anterior wall of the sphenoidal sinus from without inward, and thus reach the posterior part of the septum nisi, become attached to it, and changing their direction descend forward along it, between the perios teum and mucous membrane.
The short, lesser, branch is situate very near to the posterior margin of the septum, to which it is parallel in its course, and distri butes its filaments to the membrane of the posterior part of it : one of them is repre sented by Arnold as constituting the phar goal branch.
The long branch descends to the superior aperture of the anterior palatine canal, enters the canal, and in it the nerves of the two sides are united to a small ganglion denominated the naso palatine; from it filaments descend to the anterior part of the palate, in which they are distributed and communicate with filaments of the palatine nerves. Each nerve, during its course along the septum, is situate nearer to its position inferior than to its supe rior anterior margins: it is said not to give any filaments during its descent, but this is incorrect, as is well represented by Arnold ; those, which it gives oft; are distributed to the membrane of the septum about its middle; at times also it divides into two filaments, which are afterwards reunited. Each nerve is received inferiorly in a separate canal, which inclining inward is soon united to the other in the palatine, and in it the nerve or the naso-palatine ganglion receives a filament of communication from the anterior superior den tal branch of the second division of the fifth, as described by Cloquet.
This branch has been particularly described, first by Scarpa,* and by him denominated the naso-palatine; it has been also described by J. liunter,f between whom and Scarpa appears to lie the merit of having first ob served it ; it is also known as " the nerve of the septum," but the latter appellation is ma nifestly incorrect; nor is the former free from objection, inasmuch as the same title has been applied, and with reason, in the inferior Mam malia, to the original branch given off by the second division of the fifth for the supply of the nostril and palate, with which the spheno palatine ganglion is connected, and which in man has received the name of spheno-palatine branch. The branch of the ganglion in ques tion is called by some the nerve of Cotunnius, but incorrectly ; having been first described by Scarpa, it cannot with justice be attributed to the former.
The posterior branch of the ganglion is de scribed and represented by the majority of authorities as arising single and in its course dividing into two filaments ; but Bock, J. F.
Meckel, and Ilirzel state that the two fila ments at times are throughout distinct and connected separately to the ganglion; and Arnold represents, in like manner, two filar rents arising from the ganglion, corresponding to the two into which the single nerve divides. The posterior branch arises from the back of the ganglion, passes directly backward from it, and is received immediately into the pterygoid or Vidian canal, along with the corresponding branch of the internal maxillary artery: it is transmitted through the canal backward and slightly outward, beneath the course of the second division of the fifth itself, and external to, or in many instances beneath the sphenoidal sinus ; having traversed the canal, it escapes from its posterior aperture into the foramen lacerum anterius basis cranii : in this it is contained in the fibrous structure by which the foramen is closed, and is situate at the outer side of and beneath the internal carotid artery, as that vessel ascends, from the aperture of its canal in the petrous bone, into the cavernous sinus. Here also, or even before it has escaped from the Vidian canal, it receives, when single, a filament of com munication from the superior cervical ganglion of the sympathetic : this filament had been long regarded as arising from the posterior branch itself, and—though at present gene rally* considered a branch from the sympa thetic—it has been for the most part described, in systematic works, as such under the name of the inferior, deep, sympathic, or carotidean brunch of the Vidian nerve. In its direction it certainly resembles a branch of that nerve ; but in that particular it is equally entitled to be regarded one from the sympathetic to the spheno-palatine ganglion, it being either from before backward and from above downward, or from behind forward and from below up ward. Further, in sensible qualities it strictly resembles other branches of the latter nerve; it is, as has been stated, at times separate from the proper Vidian, and connected directly with the spheno-palatine ganglion ; and it is, in fact, but one of the branches which ascend into the cranium from the superior cervical ganglion along the internal carotid artery, so that it would be equally correct to describe that fila ment which is connected with the sixth nerve as a branch of that nerve, as to style the fila ment in question a branch of the Vidian nerve.