THE (ESOPHAGUS. 



1611 



the left after crossing the aorta. The nerves then break up into plexuses, from which 

 they emerge near the diaphragm, the left in front, the right behind the food-tube. 

 On entering the thorax, the oesophagus is in contact with the left pleura, and con- 

 tinues to be until separated from it by the aorta. Behind the pericardium it is in 

 contact with the right pleura, and just before passing through the diaphragm it is in 

 contact with both. • 



Muscular fibres bind the oesophagus to various neighboring structures. A toler- 

 ably constant band attaches it to the left bronchus, and others may go obliquely to 

 the right bronchus. Several irregular bands, mostly muscular, pass from it to various 

 parts of the pleurae and pericardium. 



Structure. — The wall of the oesophagus (3.5-4 mm. thick) consists of four 



Fig. 1363. 



Epithelium 



unica propria of 

 mucous membrane 



.^as^MuscuIaris 

 mucosa; 



,JS y /; :' "^ v- '^^gg^ i. Gland-ducts. 



Glands 





'^^^^'y^:iy'ii:^^/::^^ ;;;^^Submucous coat 





aeteT-iZ-i^ — ^ .«^^'""~^'''^"'?i->3saa£2t^~'~^^^ - '.'--T^^^iS^-  — muscle 



bundles 

 striated 



Striated fibres 



Longitudinal 

 bundles of non- 

 striated muscle 



Bundles of striated fibres 

 Transverse section of oesophagus, junction of middle with upper third. X 25- 



layers, which, from within outward, are the mucous, the submucous, the muscular, 

 and the fibrous coats. 



The mucous coat, usually thrown into longitudinal folds, is composed of a tunica 

 propria formed of fibrous connective tissue and delicate elastica and covered with 

 stratified squamous epithelium. Beneath the latter the surface of the stroma-layer 

 presents longitudinal ridges and papillse, between which pass the ducts of the glands in 

 their course to the free surface. The deeper part of this layer is occupied by a mus- 

 cularis mucos(S, the involuntary muscle of which begins at the cricoid cartilage, first 



