From the spheno-palatine ganglion or nerve, according to the view of their source adopted, there is given.off a considerable number of branches, which run in different directions and have different destinations: they have been distinguished into four sets, viz. superior, infe rior, internal, and posterior. The superior branches are very delicate and, in some in stances at least, numerous. Among them are described and represented by Arnold two long slender filaments, which join the optic : ano ther is also mentioned by him to be sometimes found connected with the ophthalmic ganglion. The discovery of this connection between the two ganglia is due to Tiedemann, who found, upon the left side of a man, an anastomosis between them, established by a filament, of tolerable size, which, arising from the inner face of the spheno-palatine, entered the orbit and passing above the inferior branch of the motor oculi nerve, where it gives off the short root, went in company with the last to gain the in ferior and posterior part of the ophthalmic gan glion ;* and beside those there may be found, in favourable subjects, others, which seem destined to the posterior ethmoidal cells. The inferior branch is the largest given off by the ganglion ; it is distributed principally to the palate, and hence is called " the palatine ;" but it supplies the nostril also in part, and hence it has been suggested by J. F. Meckel, that it might he appropriately called the " naso-palatme:" this appellation has, however, been applied by Scarpa to one of the internal branches, and it has been already explained that it belongs more properly to the original branch before its junction with the ganglion. The palatine nerve descends from the ganglion into the spheno-maxillary fossa, posterior to the internal maxillary artery and toward the pterygo-palatine canals, and after a short course divides into three branches ; an anterior, larger one, denominated " the great palatine," and two posterior smaller branches, " the lesser palatine nerves." These branches continue to descend in com pany until they reach the superior apertures of the canals ; they then enter the canals and are transmitted downward through them to the palate and fauces. The great palatine descends through the anterior pterygo-palatine canal, in company with a branch of the palatine artery, at the same time inclining forward : during its descent it gives off, in some in stances before, in others after it has entered the canal, either one or two filaments, which descend inward, pass through the nasal process of the palate bone, and enter the nostril at the back part of the middle meatus, between the posterior extremities of the middle and in ferior turbinate bones : one of them is dis tributed to the membrane of the middle bone and of the middle meatus; the other to that of the convex surface of the inferior bone : when a single branch arises from the palatine it divides into two, which follow a similar distribution ; these branches are denominated by the elder Meckel inferior nasal nerves in con tradistinction to the superior nasal, to be de scribed, given off by the ganglion and by the Vidian nerve. Another filament is described by Cloquet arising from the palatine shortly before it escapes from the canal, entering the nostril through the perpendicular plate of the palate bone, running along the margin of the inferior turbinate bone, and lost upon the ascending process of the superior maxillary bone, often also contained in an osseous canal.
The great palatine nerve, then, for the most part divides into three branches, of which one, the smallest, descends through an accessory canal, in the pterygoid process of the palate bone, leading from the anterior, and escapes from it inferiorly into the soft palate in which it is consumed.
The other two escape from the pterygo palatine canal, through the posterior palatine foramen, into the palate : at emerging from the foramen they are situate very far back, in the posterior angle of the hard palate on either side, and behind the last molar tooth of the upper jaw; they are immediately super ficial to the periosteum, and above the other structures of the palate ; they are lodged, along with the branches of the accompanying artery, in channels upon the inferior surface of the palatine processes of the palate and the superior maxillary bones; they pass forward, one along the alveolar arch, the other toward the middle line of the palate, and subdivide, each, into several branches, which are dis tributed to the structures of the hard palate, the mucous glands and membrane, and to the gums, and communicate in front with branches of the naso-palatine ganglion.
In some instances the palatine nerve does not divide into those ultimate branches until after it has escaped from the palatine canal ; but their disposition in such cases is in other respects the same.
The lesser palatine nerves are posterior to the greater ; they are transmitted also through the pterygo-palatine canals, the first through the posterior, the second through the external.
The first, the larger of the two, and called middle palatine nerve, escapes from the canal inferiorly in front of the hamular process of the sphenoid bone, and divides into filaments; which are distributed to the soft palate and its muscles.
The second, the posterior, little palatine nerve, descends at first between the external pterygoid muscle and the posterior wall of the antrum, then enters the canal, and escapes inferiorly external to the former; it divides into two filaments, one of which is distributed to the soft palate, the other to the tonsils and arches of the palate.
Those branches are accompanied by minute branches of the palatine artery.
The internal branches vary in number from three to five; they arise from the inner surface of the ganglion, run directly inward, posterior to the nasal branch of the internal maxillary artery, toward the spheno-palatine foramen, which they immediately reach ; pass through the foramen, perforating the structure by which it is closed, and enter the nostril, and thus attach the ganglion closely to the foramen : at their entrance into the nostril they are situate before and beneath the anterior wall of the sphenoidal sinus, at the back part of the su perior meatus, and immediately above the posterior extremity of the middle turbinate bone.
They are distinguishable, according to the majority of descriptions, into two sets; one destined to the outer wall of the nostril and denominated by AIeckel anterior superior nasal, in contradistinction to branches of the Vidian nerve, which he has designated posterior superior nasal," and another con nected with the septum. A third destination has been assigned to them by Arnold, accord ing to whom a branch derived either from one of the nerves of the septum, or originally from the ganglion itself, is distributed to the supe rior part of the pharynx, corresponding to the pharyngeal branch of Bock.
The anterior superior nasal branches are either one or two in number; when but one, it divides into branches corresponding to' the two; it is so expressed in Arnold's fifth plate; one of the two divides into filaments, which arc distributed to the posterior ethmoidal cells, to the posterior part of the superior turbinate bone, and to the superior meatus, to the mem brane of those parts. The second distributes its filaments to the convex surface of the mid dle turbinate bone; according to Cloquet they in part perforate the bone, and thus gain its concave surface : they all run between the periosteum and the mucous membrane, and are distributed finally to the latter.