STRUCTUKE OF THE CESOPHAGCS 



345 



Fig. 2i2. 



with those of the lateral bundles to form a continuous layer around 



the tube. The internal or circular fibres are separated above by the 



fibres of the lateral longitudinal fasciculi from those of the inferior 



constrictor of the pharynx. The rings which they form around the 



tube have a horizontal direction at 



the upper and lower part of the 



oesophagus, but in the intervening 



space are slightly oblique. At the 



lower end of the oesophagus, both 



layers of fibres become continuous 



\vith those of the stomach. 



The muscular coat of the upper 

 end of the oesophagus is of a well- 

 marked red colour, and consists 

 wholly of striped muscular fibres; 

 but lower down, where it becomes 

 somewhat paler, these are gradually 

 replaced by plain muscular fibres, 

 which form almost the whole of the 

 lower half. A few striped fibres, 

 however, are found mixed with 

 the others throughout its whole 

 length, and even, it is said, on the 

 cardiac end of the stomach (Ficinus). 



The long-itudinal fibres of the oeso- 

 pliagus are observed by Hyrtl to be 

 sometimes joined by a broad band of 

 smooth muscle, passing upwards from 

 the left pleui'a, and sometimes also by 

 another from the left bronchus. 



1 >""^i- 



The areolar or submucous coat 

 is placed between the muscular and 

 mucous coats, and connects them 

 loosely together. It exceeds the 

 mucous membrane considerably in 

 thickness, and in it are contained 



mucous gland, of wliieli the saccular part is 

 seen imbedded iu the submucous tissue ; i, 

 fat vesicles. 



Fig. 242. — Section of the Coats ov the 

 Human OEsophagus, 50 Diameters 

 Kolliker). 



The section is transverse, and from near 

 the middle of the guUet. a, fibrous cover- 

 ing ; 6, diAdded fibres of the longitudinal 

 muscular coat ; c, transverse muscular 

 the glands (fig. 242), which open on fibres ; d, submucous or areolar layer ; 

 the mucous membrane. /, papilke of mucous membrane ; (j, kmi- 



The mucous membrane is of ^^'^^^^^ epithelial^ limng ; h, opening of a 



firm texture, and is paler in colour 



than that of the pharynx or stomach. 



From its loose connections its outer 



surface is freely movable on the muscular tunic ; and when the latter 



is contracted, as happens when the oesophagus is not giving passage 



to food, the mucous lining is thrown into "longitudinal folds, which 



are in mutual contact. These folds disappear again on distension of the 



canal. 



Minute papillge (/) are seen upon the mucous membrane, and the 

 whole is covered with a thick stratified scaly epithelium, which can be 

 traced as far as the cardiac orifice of the stomach, where it suddenly 

 passes into one of a diff'erent character, as will be hereafter noticed. 



The small compound racemose glands, named msophageal glands, 

 which are for the most part situate as before stated in the submucous 



