822 



THE (ESOPHAGUS. 



prevails throughout the whole length of the alimentary canal ; but the two 

 layers are here much thicker, more uniformly disposed, and more evident 

 than in any other part except quite at the lower end of the reotum. The 

 external or longitudinal fibres are disposed at the commencement of the 

 tube in three fasciculi, one in front, and one on each side of the oeso- 

 phagus. The lateral fasciculi are blended above with the inferior constrictor 

 of the pharynx ; the anterior fasciculus arises from the back of the cricoid 

 cartilage at the prominent ridge between the posterior crico-arytenoid 

 muscles, and its fibres spreading out obliquely on each side of the gullet as 

 they descend, soon blend with those of the lateral bundles to form a con- 

 tinuous layer around the tube. The internal or circular fibres are separated 



Fig 576. Fig. 576. SECTION OP THE COATS OP THE 



HUMAN (ESOPHAGUS (from Kolliker). ^~ 



The section is transverse, and from near 

 the middle of the gullet, a, fibrous covering ; 

 b, divided fibres of the longitudinal mus- 

 cular coat ; c, transverse muscular fibres ; 

 d, submucous or areolar layer ; e, mucous 

 membrane ; /, its papillae ; g, laminated 

 epithelial lining ; h, opening of a mucous 

 gland, of which the cellular part is seen 

 embedded deeply in the mucous membrane ; 

 i, fat-vesicles. 



above by the fibres of the longi- 

 tudinal fasciculi from those of the 

 inferior constrictor of the pharnyx. 

 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 

 with those of the stomach. 



The muscular coat of the upper 

 end of the oesophagus is of a well- 

 marked red colour, and consists of 

 striped muscular fibres ; but lower 



down it becomes somewhat paler, and is principally composed of the plain 

 muscular fibres. A few striped fibres, however, are found mixed with the 

 others, and have been traced throughout its whole length, and even, it is 

 said, upon the cardiac end of the stomach. (Ficinus.) 



The longitudinal fibres of the oesophagus are observed by Hyrtl to be sometimes 

 joined by a broad band of smooth muscle, passing upwards from the left pleura, and 

 sometimes also by another from the left bronchus. 



The areolar coat is placed between the muscular and mucous coats, and 

 connects them loosely together. 



The mucous membrane is of 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, the inner surfaces of which are in 

 mutual contact. These folds again disappear on distension of the canal. 



