TEE (ESOPHAGUS. 



377 



COMPARISON OP THE PHAKYNX OF MAN WITH THAT OP ANIMALS. 



In consequence of the smallness of the soft palate, the pharynx of Man is only a 

 land of channel between the mouth and the larynx and oesophagus. ' It is usually 

 divided into three portions : a superior, the posterior nares, covered by ciliated epithelium ; 

 a middle, or guttural, and an inferior, or cesophageal ; the two latter are covered with 

 tesselated epithelium. 



The muscles are almost the same as in the Dog, being a portion of the palato-pharyn- 

 geus, the superior, middle, and inferior constrictors, and a stylo-pharyngeal muscle. 



Below the sides of the pharynx, and between the pillars of the soft palate, are the 

 amygdalse : almond-shaped organs, whose surface shows the openings of the follicles that, 

 with the vessels and a little connective tissue, compose their substance. 



THE (ESOPHAGUS. (FigS. 178, 179.) 



Preparation. Place the subject in the first or second position ; remove the subcu- 

 taneous cervical muscle from the left side; take away 

 the corresponding anterior limb, and proceed to the Fig. 177. 



excision of the ribs of this side, with the exception of the 

 first. Afterwards dissect the vessels and nerves in the 

 neighbourhood of the cesophageal canal, taking care to 

 preserve their relations to each other. 



Form. The oesophagus is a long, cylindrical, 

 narrow, membranous canal, easily dilated for the 

 greater part of its extent, and destined to convey 

 the food from the pharynx to the stomach, and to 

 complete the act of deglutition. 



Course. This canal begins at the pharynx, 

 and communicates with it by means of the pos- 

 terior opening situated above the glottis. 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 open- 

 ing of the right pillar of the diaphragm, in 

 passing between the two layers of the posterior 

 mediastinum. Traversing this opening, it pene- 

 trates 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 cellular tissue, which unites it in a loose manner to the 

 surrounding organs, its relations with these varying as we consider them 

 superiorly or inferiorly. 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 



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- 

 form opening of the larynx ; 



11, Posterior part of larynx ; 



12, Opening of oesophagus, 

 13 ; 14, Trachea. 



