SPHEXO-PALATINE GANGLION. 141 



membrane on the middle and lower spongy bones ; in the roof of the 

 mouth it supplies the mucous membrane and glands, and gives an offset to 

 the soft palate. 



The small palatine nerve, 10 (posterior), lies in the smaller canal, and 

 ends inferiorly in the soft palate, and the levator palati and azygos uvulse 

 muscles ; it supplies the uvula and tonsil. 



The external palatine nerve is smaller than the other two, and de- 

 scends in the canal of the same name. Leaving the canal, the nerve is 

 distributed to the velum palati and the tonsil. 



The pharyngeal branch is very small, and is directed through the 

 pterygo-palatine canal to the mucous membrane of the pharynx near the 

 Eustachian tube, in which it ends. 



Branches to the orbit. Two or three in number, these ascend through 

 the spheno-maxillary fissure, and end in the fleshy layer of the musculus 

 orbitalis (p. GO). It will be necessary to cut through the sphenoid bone 

 to follow these nerves to their termination. 



Connecting branches. The ganglion is united, as before said, with the 

 spheno-palatine branches of the fifth nerve (fig. 24, 3 ), receiving sensory 

 nerve fibres through them ; and through the medium of the vidian, which 

 is described below, it communicates with a motor nerve (facial) and with 

 the sympathetic nerve. 



The vidian nerve ( 8 ) passes backwards through the vidian canal, and 

 sends some small filaments, through the bone, to the membrane of the back 

 of the roof of the nose (ripper posterior nasal branches). At its exit from 

 the canal, the nerve receives a soft reddish offset (carotid branclf) from 

 the sympathetic on the outer side of the carotid artery. The continuation 

 of the nerve enters the cranium through the cartilaginous substance in the 

 foramen lacerum (basis cranii), and is directed backwards in a groove on 

 the surface of the petrous part of the temporal bone, where it takes the 

 name of large superficial petrosal nerve (fig. 35, 2 ). Lastly it is continued 

 through the hiatus Fallopii, to join the gangliform enlargement on the 

 facial nerve. Whilst in the temporal bone, the vidian receives a twig 

 from the tympanic nerve. 



The vidian nerve is supposed to consist of motor and sympathetic fibres 

 in the same sheath, as in the connecting branches between the sympa- 

 thetic and spinal nerve. 



Directions. The student may now give his attention to the remaining 

 nerves in the nasal cavity. 



Dissection. The nasal nerve is to be sought in the nose behind the 

 nasal bone (fig. 34), by gently detaching the lining membrane, after 

 having cut off the projecting bone. A branch is given from the nerve to 

 the septum nasi, but probably this, and the trunk of the nerve, will be 

 seen but imperfectly in the present condition of the part. 



The terminal branches of the internal maxillary artery in the spheno- 

 maxillary fossa have been laid bare in the dissection of Meckel's ganglion, 

 but they may be now completely traced out. 



The nasal nerve (of the ophthalmic) (fig. 34, 6 ) has been already seen 

 in the skull and orbit. Entering the nasal fossa by an aperture at the 

 front of the ethmoid bone, the nerve gives a branch to the membrane of 

 the septum, and is continued in a groove behind the os nasi to the lower 

 margin of this bone where it escapes to the surface of the nose in the 

 face (fig. 9, 7 ). 



