SPECIAL ANATOMY. 127 



and tlie motor root runs over its under surface. From the 

 ganglion three branches pass : — One runs to combine with 

 the motor tract to form the inferior maxillary division, 

 which passes through foramen lacerum basis cranii, as 

 ah'eady noticed ; another, the ophthalmic division, passes 

 through foramen lacerum orbitale, in company with the 

 third, fourth, and sixth cranial nerves and the ophthalmic 

 artery, and thus gains the orbit. The third, or superior 

 maxillary division, passes from the cranium, and emerges 

 with the internal maxillary artery through foramen rotun- 

 dum. It may be seen with this vessel passing to the maxil- 

 lary hiatus, prior to gaining which it divides into three parts, 

 corresponding to the terminal branches of the artery. The 

 superior dental hranch passes through canalis infra-orbitale, 

 and, like the artery, supplies the upper teeth ; but a very 

 large branch passes through the infra-orbital foramen, 

 where it is covered by levator labii superioris alaeque nasi. 

 It blends with a large branch from the facial nerve, forming 

 the superior labial nerve, and the plexus of 7ierves over the 

 lateral part of the muzzle formed hy the union of the infra- 

 orbital, anterior maxillary, and facial nerves corresponds to 

 the "pes anserinus " of the human subject The palato- 

 maxillary nerve, passing with the artery of the same through 

 the palatine canal, gains the hard palate, which it supplies 

 with sensation ; it also sends fibres to the soft palate. The 

 spheno-palatine nerve, passing with the spheno -palatine 

 artery through the foramen of the same name, gains the 

 nasal chamber, the inferior and middle meatus of which it 

 supplies with common sensation. At its origin it forms a 

 close connection by means of numerous fibres with the 

 spheno-palatine or Meckel's ganglion, a collection of nerve- 

 cells, which receives motor fibres through the vidian branch 

 of the seventh cranial nerve, and is supposed to send 

 efferent fibres to the palate. 



We have now exposed the mouth, a cylindrical cavity 

 elongated in an antero-posterior direction, presenting four 

 surfaces and two extremities. The anterior extremity is 

 guarded by the lips, between which is the labial fissure. 

 The posterior extremity presents the anterior opening of the 

 fauces, bounded on either side by the reflections of mucous 

 membrane from the palate to the base of the tongue, the 

 posterior pillars of the tongue. Through this opening the 

 pendulous palate and the cavities of the tonsils are visible. 



