TEE (ESOPHAGUS. 



447 



Fig. 253. 



The (Esophagus (Figs. 254, 255). 



PreparaUon. — Place the subject in the second or third position ; remove the cervical 

 panniculus from the left side ; take away the corresponding anterior limb, and proceed to the 

 excision of the ribs of this side, with the exception of the first. Afterwards dissect the vessels 

 and nerves in the neighbourhood of the oesophagus, taking care to preserve their relations with 

 each other. 



Form. — The oesophagus is a long, cyhndrical, narrow, membranous canal, a 

 little wider below its commencement, easily dilated for the greater part of its 

 extent, destined to convey the food from the pharynx to the stomach, and 

 so to complete the act of deglutition. 



Course. — It begins at the pharynx, and communicates with it by means of 

 the posterior opening situated above the glottis. It 

 is so narrow when not in use, that it admits with 

 diflficulty the tip of the finger. Behind, it is circum- 

 scribed by a fibro-mucous cord that is related to the 

 junction of the posterior pilhrs of the soft palate ; 

 in front, by the external surface of the arytsenoid 

 cartilages. It afterwards descends behind the trachea 

 to the middle of the neck, where it commences to 

 deviate towards the left side of that tube, and enters 

 the thoracic cavity by inclining towards the inner 

 aspect of the first left rib. It soon after regains its 

 situation above the trachea, passes over the base of 

 the heart, and reaches the opening in the right pillar 

 of the diaphragm, in passing between the two layers 

 of the posterior mediastinum. Traversing this open- 

 ing, it enters the abdominal cavity, and immediately 

 afterwards is inserted into the smaller curvature of 

 the stomach by an orifice designated the cardiac, which 

 will be studied at the same time as that viscus. 



Relations. — The oesophagus in its course has the 

 following numerous relations : — 



At its origin, it is comprised between the guttural 

 pouch and the posterior crico-arytenoid muscles. 



In the cervical region, it is enveloped in a thick 

 layer of connective tissue, which unites it in a loose 

 manner to the surrounding organs, its relations with 

 these varying as we consider them superiorly or in- 

 feriorly. Superiorly, and in the median plane, it 

 occupies the space included between the trachea and 

 the longus-colli, being bordered on each side by the 

 common carotid artery, with its satellite nerves — the 



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

 laryngeal. Inferiorhj, it is related to the trachea on the inner side ; and, exter- 

 nally, to the inferior scalenus muscle, and the vessels and nerves in the left 

 cervical channel, which also includes the jugular vein.^ 



' It is not absolutely rare to find the oesophagus deviate to the right in the lower part of 

 the neck ; in this case its relations will be reversed. We have never seen this canal enter the 

 thorax in the median plane of the body. 



In Horses with a flat trachea, the oesophagus is sometimes in the middle of the upper 



HUMAN PHARYNX LAID OPEN 

 FROM BEHIND. 



1, Section through base of 

 skull; 2, 2, walls of pha- 

 rynx drawn aside ; 3, 3, 

 posterior nares, separated 

 by the vomer ; 4, extremity 

 of one Eustachian tube ; 5, 

 soft palate ; 6, posterior 

 pillar of soft palate ; 7, an- 

 terior pillar ; 8, root of the 

 tongue, partly concealed by 

 the uvula ; 9, epiglottis 

 overhanging (10) the cordi- 

 forra opening of the larynx ; 



11, posterior part of larynx ; 



12, opening of oesophagus, 

 13 ; 14, trachea. 



