HEAD AND NECK OF THE HORSE 63 



(4) N. huccinatoruis. — The relatively large buccinator nerve 

 usually leaves the mandibular in common with the pterygoid nerve. 

 It runs downwards and forwards across the medial aspect of tlie 

 mandibular joint and over the origin of the external pterygoid muscle 

 to gain the deep face of the masseter, where an examination of it has 

 already been effected (page 51). 



(5) N. temporalis superficialis. — The superficial temporal nerve 

 bends round the back of the mandibular joint, where it lies upon the 

 joint-capsule, to gain the face and divide into two branches, as the 

 dissection of the face has shown (page 37). 



(6) xY. alveolaris inferior. — The inferior alveolar and lingual nerves 

 leave the mandibular as a common nerve-cord that crosses obliquely 

 over the lateral face of the internal maxillary artery. Thereupon the 

 two nerves separate. 



The inferior alveolar nerve passes between the two pterygoid 

 muscles in company with the inferior alveolar vessels. The three 

 structures then run between the internal pterygoid muscle and the 

 mandible and enter the mandibular canal together. The nerve supplies 

 branches to the teeth and gums and emerges from the mandibular 

 canal by the mental foramen as the mental nerve (n. mentalis), which 

 ends in a number (six or more) of branches that ramify in the lower lip 

 and the region of the chin. 



The mylo-hyoid nerve (n. mylohyoideus) leaves the inferior alveolar 

 at the mandibular foramen and follows a shallow groove on the medial 

 surface of the mandible. It supplies the mylo-hyoid and mylo-glossal 

 muscles and the anterior belly of the digastricus. 



(7) N. lingualis. — The lingual nerve is almost as large as the 

 inferior alveolar. At first it lies between the internal pterygoid muscle 

 and the mandible, and then between the mylo-hyoid and stylo-glossal 

 muscles. Its course within the tongue will be determined later. 



Close to its independent origin, or even while still in union with the 

 inferior alveolar, the lingual nerve is joined by the chorda tympani, a 

 branch of the seventh cerebral nerve. 



N. GLOSSOPHARYNGEUS. — The glosso-pharyngeal or ninth cerebral 

 nerve will be found between the great cornu of the hyoid bone and the 

 external carotid artery, where it lies on the diverticulum of the 

 auditory tube. Its pharyngeal branch (ramus pharyngeus) crosses the 

 medial surface of the great cornu to reach the wall of the pharynx, 

 where it comes into relation with the ascending palatine artery. Along 

 with branches of the vagus and other nerves it assists in the formation 

 of the pharyngeal plexus. The lingual branch (ramus lingualis) 

 continues the line of the course of the main nerve — of which it is much 



