798 NERVOUS SYSTEM OF THE HORSE 
part of the hard palate. The lateral branch (Ramus lateralis) ramifies in the 
mucous membrane of the ventral turbinate and the middle and ventral meatus nasi. 
(2) The greater or anterior palatine nerve (N. palatinus major s. oralis) (Figs. 
563, 564) is the largest of the three branches. It runs forward in the palatine canal 
and groove and ramifies in the hard palate and gums. It also supplies twigs to the 
soft palate, and gives off branches which pass through the accessory palatine for- 
amina to supply the mucous membrane of the ventral meatus. 
The branches of the two nerves anastomose in the hard palate and form a plexus about the 
branches of the palatine arteries. 
(3) The lesser or posterior palatine nerve (N. palatinus minor s. aboralis), 
also termed the staphyline, is much the smallest of the three branches (Figs. 563, 
564). It passes downward and forward with the palatine vein in the groove at the 
medial side of the tuber maxillare and ramifies in the soft palate. 
The sphenopalatine ganglia and plexus (Fig. 647) lie on the perpendicular part of the palatine 
bone and the pterygoid process, under cover of the maxillary nerve. The afferent fibers of the 
plexus and ganglia come chiefly from the branches of the sphenopalatine nerve and the nerve of 
the pterygoid canal. Interspersed in these are several mimute gangha and one or more larger 
ones. ‘The nerve of the pterygoid canal (N. canalis pterygoidei)! is formed by the union of sym- 
pathetic fibers with the superficial petrosal branch of the facial nerve. It passes forward at first 
between the Eustachian tube and the sphenoid bone, enters the canal between the pterygoid bone 
and process, and joins the posterior part of the plexus. It is probable that it furnishes the motor 
fibers to the levator palati and palatinus muscles. Efferent filaments go to the periorbita and the 
ophthalmic vessels, and others accompany the branches of the maxillary nerve, around which they 
have a plexiform arrangement. 
3. The infraorbital nerve (N. infraorbitalis)? is the continuation of the maxillary 
trunk. It traverses the infraorbital canal, emerges through the infraorbital fora- 
men, and divides into nasal and superior labial branches. Along its course it gives 
off maxillary alveolar or dental branches (Rami alveolares maxille), which supply 
the teeth, alveolar periosteum, and gums. 
Small posterior alveolar branches (Rami alveolares maxilla aborales) are given off in the 
pterygo-palatine fossa, pass through small foramina in the tuber maxillare, and supply the posterior 
molar teeth and the maxillary sinus. The middle alveolar branches (Rami alveolares maxille 
medii) are given off in the infraorbital canal, and constitute the chief nerve-supply to the cheek 
teeth and the maxillary sinus. The maxillary incisor branch (Ramus alveolaris maxille incisivus) 
runs forward in the incisor canal and supplies branches to the canine and incisor teeth, The fore- 
going unite with each other to form the maxillary dental plexus (Plexus dentalis maxille) from 
which the dental and gingival branches are given off. 
The external nasal branches (Rami nasales externi), two or three in number, 
accompany the levator labii superioris proprius and ramify in the dorsum nasi and 
the nasal diverticulum. 
The large anterior nasal branch (Ramus nasalis oralis) gives branches to the 
upper lip and nostril, passes over the nasal process of the premaxilla under cover 
of the lateralis nasi, and ramifies in the mucous membrane of the nasal vestibule. 
The superior labial branch (Ramus labialis dorsalis) is the largest of the termi- 
nals of the infraorbital nerve. It passes downward and forward under cover of the 
levator nasolabialis and, after supplying the skin of the anterior part of the cheek, 
forms a rich terminal ramification in the skin and mucous membrane of the upper 
lip. It anastomoses with the superior buccal branch of the facial nerve. 
III. The mandibular nerve (N. mandibularis)* is formed by the union of two 
roots; of these, the large sensory root comes from the semilunar ganglion, and the 
small motor root is the pars minor of the trigeminus. It emerges from the cranium 
through the oval notch of the foramen lacerum, and passes between the temporal 
wing of the sphenoid bone and the muscular process of the petrous temporal. It 
then runs forward, downward, and a little outward, between the ventral surface of 
1 Also known as the Vidian nerve. 2 This is also called the superior dental nerve. 
8 This is also termed the inferior maxillary branch. 
