880 



THE SENSE ORGANS AND SKIN OF THE HORSE 



sally it covers the mandibular nerve and its chief branches, and is attached to the 

 styloid process of the conchal cartilage. 



Each pouch communicates with the pharynx through the pharjmgeal orifice 

 of the Eustachian tube, and is in direct continuity with the mucous membrane of 

 the latter. 



The average capacity of each pouch is about ten fiuidounces (ca. 300 c.c); of 

 this, the lateral compartment is about one-third. 



Temporal muscle 



Scutiform cartilage, 

 posterior process 



Conchal cartilage 



Brachioce phalicus 

 tendon, 



Nerves IX, X, XI 



Ventral cerebral vein 

 Internal carotid artery 

 Guttural pouch 

 Occipito-hyoideus 



muscle 



Jugular vein 



Int. maxillary artery 

 Ext. maxillary artery 



Parapharyngeal lymph 

 glands 



Occipito-mandibularis 

 muscle 



Sterno-cephalicus tendon 

 Mandibular gland 

 Thyroid cartilage 

 Ext. maxillary vein 



Omo-hyoidei + sterno-hyoidei 

 Fig. 706. — Cross-section of He.^d of Horse. 

 The section passes through the base of the external ear and just behind the posterior border of the mandible. /, 

 Rectus capitis ventralis minor; S, rectus capitis ventralis major; 3, medial walls of guttural pouches in apposition; 

 4, U. arytenoid cartilage, upper piece being apex; 5, posterior pillar of soft palate; Q, false vocal cord; 7, lateral ventricle 

 oflarj'nx; 5, true vocal cord ; 5*, vocal muscle; 70, thyro-hyoideus muscle. The cavity in which the number 5 is placed 

 is the pharynx, which was left unmarked by an oversight. 



The pouch is a delicate mucous membrane which is in general rather loosely 

 attached to the surrounding structures. It is lined with ciliated epithelium and is 

 supplied with glands which are chiefly mucous in type. 



It is worthy of note that the pharyngeal orifice of the Eustachian tube is at such a level as 

 to provide (in the ordinary position of the head) only an overflow outlet for the escape of fluid 

 which may accumulate in the pouch. The expanded part of the tube forms with the wall of the 

 pharynx a sort of vestibule, at the posterior part of which is the opening of the guttural pouch. 



