222 THE FIFTH PAIR OF NERVES. 



branch to the ^membrana nictitaus/ aud then takes a 

 singular course. Some ramifications go to the frontal 

 sinuses and the foramina, and, piercing the orbit of 

 the eye for this purpose, present a beautiful view in 

 young animals, particularly the sheep. The main 

 branch then enters the cranium again through the 

 internal orbital foramen, passes under the dura mater, 

 returns through the cribriform plate, and ramifies on 

 the membrane of the nose, sending some branches as 

 low as the false nostril and alae. 



'^ The superior riiaxillary nerve, or second branch of 

 the trigeminus, contains little that is peculiar to or 

 has a practical tendency in quadrupeds. The different 

 situation and conformation of the bones of the face 

 cause the principal or only variation in the distribu- 

 tion of this branch in the biped and the quadruped. 

 It leaves the cranium through the foramen rotundum, 

 and at the base of the skull gives off small ramifica- 

 tions to the inner canthus of the eye, the antrum, and 

 the two posterior grinder teeth. It also supplies the 

 lateral portion of the nasal cavity through the spheno- 

 palatine foramen, while filaments are given off from 

 the origin of the trunk to the temporal muscle. A 

 branch also runs along the upper border of the septum 

 nasi to the palate, and a larger branch, which trav- 

 erses the palate in company with its blood-vessels, 

 passes through the foramen incisivum to "the upper 

 lip. The main trunh of the nerve now enters into the 

 superior and exterior foramen, in the hiatus between 

 the palatine bone and the tuberosity of the superior 

 maxillary bone, leading into a bony canal (easily traced 

 in the horse) between the maxillary sinus and the an- 

 trum, and appearing as a great pillar passing tlirough 

 the palatine sinuses in the ox. It traverses this canal, 



