682 



NERVOUS SYSTEM OF THE HORSE 



buccinator nerves, and is related intcn-nally to the tensor palati and the Eustachian 

 tube. It receives motor fibers from the pterygoid nerve and sensory fibers by the 

 small superficial petrosal nerve from the tympanic plexus, through which communi- 

 cations are made with the facial and glosso-pharyngeal nerves. Sympathetic 

 fibers are derived from the plexus on the internal maxillary artery. Efferent fila- 

 ments go to the tensor palati, tensor tympani, and pterygoid muscles, and to the 

 Eustachian tube. 



The ganglion is small and somewhat difficult to demonstrate. 

 by a number of minute gangha interspersed in a fine plexus. 



In many cases it is replaced 



5. The superficial temporal nerve (N. temporalis superficialis) (Figs. 437, 

 514, 515) runs outward across the pterygoideus externus, passes between the parotid 

 gland and the neck of the ramus of the mandible, turns around the latter, and di- 

 vides into two branches. The upper branch (Ramus transversus faciei) accom- 



FiG. 515. — Deep Dissection of Base of Cranium, Viewed from the Right and Below. 

 The tympanic cavity is opened and the paramastoid process is sawn off. a, Occipital condyle; b, body of 

 sphenoid; c, external auditory meatus (part removed); d, malleus; e, incus; 1, stump of ophthalmic nerve; $, 

 maxillary nerve (cut off); 3, sphenopalatine plexus; 4, Vidian nerve; 4 , deep petrosal nerve; 4", branch to 

 tympanic plexus; 4'", superficial petrosal nerve; 6, superficial temporal nerve (cut off); 6, masseteric nerve (cut 

 off); 7, mandibular nerve (raised) ; S, lingual nerve (cut off) ; 9, pterygoid nerve (cut) ; iO, nerve to tensor tympani; 

 J/, otic ganglion; i^, facial nerve; /3, stapedial nerve; 14, chorda tympani; 15, glosso-pharyngeal nerve (cut); 

 16, tympanic nerve; 17, vagus (cut off); IS, auricular branch of vagus; 19, spinal accessory nerve (cut off); SO, 

 hypoglossal nerve (cut off); 31, sympathetic nerve (cut off); 22, internal carotid artery. (After EUenberger, 

 in Leisering's Atlas.) 



panics the transverse facial vessels and ramifies in the skin of the cheek. The larger 

 inferior branch unites with the inferior buccal division of the facial nerve. 



Before its division the nerve gives off twigs to the guttural pouch, the parotid 

 gland, the external ear, and the skin of the external auditory meatus and the mem- 

 brana tympani. Branches from it concur with filaments from the cervical branch 

 of the facial nerve in the formation of the auricular jilexus. 



6. The inferior alveolar or dental nerve (N. alveolaris mandibular) (Figs. 

 436, 437, 514) arises with the lingual by a common trunk which passes forward at 

 first on the external pterygoid muscle, then inclines ventrally between the internal 

 pterygoid and the ramus of the mandible. The lingual and alveolar separate at an 

 acute angle, and the latter enters the mandibular foramen and courses in the canal 

 within the ramus (Fig. 516). Emerging at the mental foramen, it terminates by 

 dividing into six to eight inferior labial and mental branches, which ramify in the 

 lower lip and chin. Before entering the bone, the nerve detaches the mylo-hyoid 

 nerve (N. mylohyoideus), which runs downward and forward between the ramus 

 and the mylo-hyoid muscle; it supplies that muscle, the anterior belly of the 

 digastricus, and the skin of the anterior part of the submaxillary space. The dental 



