804 THE NERVOUS SYSTEM. 



The large superficial petrosal branch (nervus petrosus superficialis major] is 

 given off from the intumescentia ganglioformis in the aqueductus Fallopii; it 

 passes through the hiatus Fallopii ; enters the cranial cavity, and runs forward 

 contained in a groove on the anterior surface of the petrous portion of the 

 temporal bone, lying beneath the dura mater and the Gasserian ganglion. It 

 then enters the fibrous substance which fills in the foramen lacerum medium basis 

 cranii, and, joining with the large deep petrosal branch, forms the Vidian nerve. 



The large deep petrosal branch (nervus petrosus profundus) is given off from 

 the carotid plexus, and runs through the carotid canal on the outer side of the 

 internal carotid artery. It then enters the fibrous substance which fills in the 

 foramen lacerum medium, and joins with the large superficial petrosal nerve to 

 form the Vidian. 



The Vidian nerve, thus formed, passes forward through the Vidian canal 

 with the artery of the same name, receives the sphenoidal filament from the otic 

 ganglion, and, entering the spheno-maxillary fossa, joins the posterior angle of 

 Meckel's ganglion. 



Its Branches of Distribution. These are divisible into four groups : ascending, 

 which pass to the orbit ; descending, to the palate ; internal, to the nose ; and 

 posterior branches, to the pharynx and nasal fossae. 



The ascending branches are two or three delicate filaments which enter the 

 orbit by the spheno-maxillary fissure and supply the periosteum. Arnold describes 

 and delineates these branches as ascending to the optic nerve. Bock describes a 

 branch as going to the cavernous sinus to communicate with the sixth nerve, and 

 Tiedemann, a communicating branch to the ophthalmic ganglion. 



The descending or palatine branches are distributed to the roof of the mouth, 

 the soft palate, tonsil, and lining membrane of the nose. They are almost a direct 

 continuation of the spheno-palatine branches of the superior maxillary nerve, and 

 are three in number anterior, middle, and posterior. 



The anterior or large palatine nerve descends through the posterior palatine 

 canal, emerges upon the hard palate at the posterior palatine foramen, and passes 

 forward through a groove in the hard palate nearly as far as the incisor teeth. It 

 supplies the gums, the mucous membrane and glands of the hard palate, and 

 communicates in front with the termination of the naso-palatine nerve. While in 

 the posterior palatine canal it gives off inferior nasal branches, which enter the 

 nose through openings in the palate bone, and ramify over the middle meatus and 

 the middle and inferior spongy bones ; and, at its exit from the canal a palatine 

 branch is distributed to both surfaces of the soft palate. 



The middle or external palatine nerve descends through one of the accessory 

 palatine canals, distributing branches to the uvula, tonsil, and soft palate. It is 

 occasionally wanting. 



The posterior or small palatine nerve descends with a small artery through the 

 small posterior palatine canal, emerging by a separate opening behind the posterior 

 palatine foramen. It supplies the Levator palati and Azygos uvulae muscles, the 

 soft palate, tonsil, and uvula. The middle and posterior palatine join with the 

 tonsillar branches of the glosso-pharyngeal to form the plexus around the tonsil 

 (circulus tonsillaris). 



The internal branches are distributed to the septum and outer wall of the nasal 

 fossae. They are the superior nasal (anterior) and the naso-palatine. 



The superior nasal branches (anterior), four or five in number, enter 

 the back part of the nasal fossa by the spheno-palatine foramen. They 

 supply the mucous membrane covering the superior and middle spongy bones, 

 and that lining the posterior ethmoidal cells, a few being prolonged to the 

 upper and back part of the septum. One branch is continued on to the inner 

 surface of the anterior wall of the antrum, and there forms a communication 

 with the anterior dental nerve. At the point of communication a swelling 

 exists, denominated "the ganglion of Bochdalek," the nature of which seems 

 to be, however, uncertain. 



