194 THE ANATOMY OF THE HORSE. 



vessels between the two pterygoid muscles, and then descends between 

 the inner muscle and the bone. It has already been traced to the 

 digastric (lower belly) and mylo-hyoid muscles. 



The Lingual or Gustatory Nerve is only slightly smaller than the 

 inferior dental. It lies immediately in front of that nerve as far as the 

 posterior edge of the external pterygoid muscle, where it passes forwards 

 between the internal pterygoid and the bone to reach the tongue. It is 

 a sensory branch ; and, while between the two muscles, it is joined by 

 the chorda tympani. 



The Chorda Tympani Nerve. This is a branch detached from the 

 7th nerve in the aqueduct of Fallopius. It passes across the 

 tympanum, or middle ear, and issues from the petrous temporal bone 

 by the styloid foramen. It then descends on the guttural pouch ; and, 

 crossing beneath the internal maxillary artery and the trunk of the 

 inferior dental nerve, it joins the lingual nerve between the two 

 pterygoid muscles. 



The Otic Ganglion. This ganglion is at best minute, and sometimes 

 absent, or at least not well defined. To examine it well, it is neces- 

 sary to make a special preparation, exposing the inner aspect of the 

 inferior maxillary nerve at its point of emergence from the cranium. 

 The ganglion is jjlaced on the inner side of the before-mentioned nerve- 

 trunk near the origin of its buccal branch. Its afferent branches are : 

 (1) twigs from the buccal branch of the inferior maxillarj' nerve ; (2) the 

 small superficial petrosal nerve from the 7th, which is given off from the 

 geniculate ganglion in the aqueduct of Fallopius, and issues from the 

 petrous temporal bone by a minute foramen to the inner side of the 

 Eustachian orifice; (3) twigs from the sympathetic branches that' 

 accompany the internal maxillary artery. It supplies efferent branches 

 to : (1) the tensor palati muscle, (2) the tensor tympani, (3) the 

 pterygoid muscles, and (4) the Eustachian tube. 



The Submaxillary Gland (Plates 27 and 31, and Fig. 23, p. 201) is, 

 in point of size, the second of the salivary glands. It is elongated, 

 with blunt, rounded extremities ; and it is curved, the concavity being 

 directed upwards and forwards. Its outer surface is related to the 

 tendon of the sterno-maxillaris muscle, to the fibrous band connecting 

 that tendon to the mastoid insertion of the mastoido-humeralis, and to 

 the internal pterygoid. The sterno-maxillaris tendon and the above- 

 mentioned fibrous band separate it from the overlying parotid. Its 

 inner surface is related to the guttural pouch, the pharynx, the larynx, 

 and the thyro-hyoid muscle ; and it conceals above the larynx the ter- 

 minal part of the common carotid artery and the 10th and 11th nerves. 

 Its posterior border is, about its centre, near or in contact with the 

 thyroid gland ; and below that point it is margined by the submaxillary 

 vein. Its anterior border is related above to the stylo-maxillaris muscle. 



