378 THE DIGESTIVE APPARATUS IN MAMMALIA. 



trunk common to the great sympathetic and pneumogastric, and the inferior 

 laryngeal. 



Inferiorly, it is related to the trachea internally; and, externally, to 

 the inferior scalenus muscle, and the vessels and nerves of the left cervical 

 channel, which also includes the jugular vein.^ 



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

 the left, and lying on the side of the trachea, responds, externally, to the 

 inferior cervical ganglion, the afferent and emergent nervous branches of 

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

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



Ficr. 178. 





TRANSVERSE VERTICAL SECTION OF HEAD AND NECK IMMEDIATELY IN FRONT OP TilE 

 STYLOID PROCESSES, AND BEHIND THE (ESOPHAGUS. 

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

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

 muscle; 8,9, 10, 11, Guttural pouch and objects in its interior; 12, Stylo- 

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

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

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



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

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

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

 with the internal face of the lungs ; these are channeled for its reception, 

 and here it is accompanied by the oesophageal artery, and the oesophageal 

 branches of the pneumogastric nerve. 



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



' It is not rare to find the oesophagus deviate to the right below the neck ; in this 

 case its relations will be inverted. We have never seen this canal enter the thorax in the 

 median plane of the body. 



