DIKSKCTION OF THE DOG 183 



traverses tlio infraorbital canal, during which it supplies vessels to the teeth, 

 and ends on the face as the dorsal and lateral nasal arteries. (5) Generally 

 arising from a stem which also gives origin to the spheno-palatine, the greater 

 palatine artery (a. palatina major) runs along the palatine canal into the hard 

 palate. Here it is continued towards the incisor teeth, behind which it ends by 

 anastomosing, in the form of an arch, with its fellow. Twigs anastomose with 

 branches of the lesser palatine vessel, and a branch of some size passes through 

 the palatine fissure into the nose. (6) The spheno-palatine artery (a. spheno- 

 palatina) at once enters the nasal cavity by way of the spheno-palatine foramen. 

 As will be seen later, the main branches of the artery ramify on the lateral wall 

 of the nasal cavity, while smaller branches supply the mucous membrane of the 

 ethmoidal cells and the nasal septum. 



N. maxillaris.- — The maxillary nerve — a division of the fifth cerebral 

 nerve — leaves the cranium by the foramen rotundum and accompanies the 

 second part of the internal maxillary artery across the pterygoid muscles. The 

 nerve is medial and somewhat dorsal to the artery. 



The following are the branches of the maxillary nerve : (1) The lachrymal 

 nerve (n. lacrimalis) and (2) the zygomatic nerve (n. zygomaticus) leave the 

 stem of the maxillary at its exit from the foramen rotundum, and soon pierce 

 the periorbita. Their terminal filaments were examined in connection with 

 the face. The middle part of their course will be disclosed during the dissection 

 of the contents of the orbit. (3) The largest branches of the maxillary nerve are 

 the two infraorbital nerves (nn. inf raorbitales) . These accompany the artery 

 of the same name along the infraorbital canal. Immediately on their emer- 

 gence from the canal, they divide into several large branches, which, after 

 further division, arrange themselves in a dorsal and a ventral group. (4) The 

 dorsal nerves — the external nasal branches (rami nasales externi) — spread out 

 over the side of the nose. (5) The ventral and larger nerves — the superior labial 

 branches (rami labiales superiores) — supply the upper lip, and more particularly 

 the tactile hairs thereof. While within the infraorbital canal, the more ventral 

 infraorbital nerve contributes filaments to the teeth, the dental branches (rami 

 dentales). (6) The spheno-palatine nerve (n. spheno-palatinus) . The dissection 

 of this nerve and its branches is facilitated by the extraction of the last two 

 cheek teeth and the removal of the lateral wall of their alveoli. The spheno- 

 palatine nerve, as such, has only a short course, inasmuch as it soon divides into 

 three parts, the lesser palatine and the greater palatine nerves, and nasal 

 branches : (a) The lesser palatine nerve (n. palatinus minor) accompanies the 

 artery of the same name into the soft palate ; (b) the greater palatine nerve 

 (n. palatinus major) also follows the vessel of the same name ; (c) the nasal 

 branches (rami nasales posteriores) enter the nasal cavity by the spheno-palatine 

 foramen. 



Ganglion spheno-palatinum. — Lying on the pterygoid muscle, and 

 generally underneath the infraorbital nerves, is the spheno-palatine ganglion, 



N 4 



