: 7- THE DIGESTIVE APPARATUS IN MAMMALIA. 



trunk 0'innum to the groat sympathetic and pneumogastric, and tin- inferior 

 laryngeal. 



'rly, it is related to the trachea internally; and, externally, to 

 tho inferior scaleuus muscle, and the vessels and nerves of the loft oervicn] 

 eluumel. which also includes tho jugular vein. 1 



At its entrance into the thoracic cavity, tho oesophagus, still deviating: to 

 the left, and lying on tho side of tho trachea, responds, < xl.-nially. t tins 

 inferior cervical ganglion, the afferent and emergent nervous brand 

 that ganglion, the vertebral arteries and veins, and the superior cervical and 

 dorso-muscular vessels, which obliquely cross its direction. Beyond //// 



Fig. 178. 



TRANSVERSE VERTICAL SECTION OF HEAD AND NECK IMMEDIATELY IN FRONT OF THE 

 STYLOID PROCESSES, AND BEHIND THE CESOPHAQUS. 



1, (Esophagus ; 2, Inner surface of trachea; 3, Common carotid artery; 4, Recur- 

 rent nerve ; 5, Thyroid gland ; 6, Exterior of pharyiix ; 7, Crico-pharyngeal 

 muscle; 8,9, 10, 11, Guttural pouch and objects iii its interior; 1'J, Stylo- 

 pharyngeus muscle; 13, Sphenoid bone; 14, Jugular ganglia; 15, Internal 

 carotid; 16, 17, Pneumogastric nerve; 18, Parotid gland; 19, Great hypoglossul 

 nerve ; 20, Jugular vein ; 21, Subscapulo-hyoideus ; 22, Stylo-maxillaris. 



it regains its position between tho trachea and the longus colli, passes 

 above the left bronchus, to the right of tho thoracic aorta, until it reaches 

 between tho layers of tho posterior mediastinum, which bring it into relation 

 with the internal faco' of tho lungs; these arc channeled for its reception, 

 and here it is accompanied by tho oosophageal artery, and tho oesophagoal 

 branches of tho pneumogastric nerve. 



The very short portion lodged in tho abdominal cavity responds, on the 



1 It is not rare to find the cchoplui^iis deviate to tin 1 ri^ht below tlic nock; in this 

 case its relations will bo inverted. We have never seen tin's canal enter the thorax in the 

 median plane of the body. 



