THE GUTTURAL POUCHES 



757 



Each pouch communicates with the pharynx through the pharyngeal orifice 

 of the Eustachian tube, and is in (hrect continuity with the mucous mein])rane of 

 the latter. 



The wall of the pouch is a delicate mucous membrane which is in general 

 rather loosely attached to the surrounding structures. It is covered with 

 ciliated epithelium and is supplied with mucous glands. 



Scutiforni cartilage, 

 posterior process 



Conchal cartilage 



Mastoido-Jiumeralis 

 tendon 



Xerves IX, X, XI 



Inferior cerebral vein 



Internal carotid artery 

 (luttjtral pouch 

 Occijnto-hyoideus 

 muscle 



— Jugular rein 



Int. niaxUlary artery 

 Ext. maxillary artery 



Pharyngeal lymph glands 

 Stylo-niaxillaris inuscle 



Sferno-cephalicris tendon 



'Submaxillary gland 

 Thyroid cartilage 



Ext. maxillary vein 



Omo-hyoidei 

 Fig. 509. — Cuoss-skction ok Hk.\d ok Horse. 

 The section pa.sses through the base of the external ear and just behind the posterior border of the lower 

 jaw. /, Rectus capitis anterior minor; ^, rectus capitis anterior major; 5, inner walls of guttural pouches in ap- 

 position; .^, 4, arytenoid cartilage, upper piece apex; 5, posterior pillar of soft palate; 6, false vocal cord; 7, lateral 

 ventricle of larynx; S, true vocal cord; 9, vocal muscle; 10, thyro-hyoideus mu.scle. 



It is worthy of note that tlio 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 two pouches are often unequal in size, and variations 

 in regard to the distance which they extend backward are not uncommon. In one case, a small 

 aged hor.se, the right pouch extended along the o'.^ophagus about five inches (ca. 12 cm.) behind 

 the ventral tubercle of the atlas, and the left one a little more than two inches (ca. 6 cm.). No 

 pathological changes were apparent, and the condition was not recognizable externally. Cases 

 of extreme size — so-called tympanites — of the pouches occur, and are apparently congenital 

 defects. In a case in a yearling colt, the head of which was 24 inches long, the left pouch extended 

 about 12 inches (ca. 30 cm.) behind the tubercle of the atlas, and had a capacity of six quarts. 



