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 gangHa 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 minute gangUa and one or more larger 

 ones. The nerve of the pterygoid canal (N. canaUs 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 maxillee), which supply 

 the teeth, alveolar periosteum, and gums. 



Small posterior alveolar branches (Rami alveolares maxillfe 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 maxillae 

 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 maxillae 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 maxillae) from 

 which the dental and gingival branches are given off. 



The external nasal branches (Rami nasales externi), two or three in number, 

 accompanj' 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 



^ Also known as the Vidian nerve. ^ This is also called the superior dental nerve. 



* This is also termed the inferior maxillary branch. 



