440 



THE ALIMENTARY CANAL. 



[CH. XXVII. 



THE (ESOPHAGUS OR GULLET. 



The (Esophagus or Gullet, the narrowest portion of the ali- 

 mentary canal, is a muscular tube, nine or ten inches in length, 

 which extends from the lower end of the pharynx to the cardiac 

 orifice of the stomach. 



Structure. The oesophagus is made up of three coats viz., 

 the outer, muscular ; the middle, submucous ; and the inner, 



fig. 371. Vertical section through a crypt of the human tonsil, i, entrance to the crypt ; 

 2 and 3, the framework of adenoid tissue ; 4, the enclosing fibrous tissue ; a and b, 

 lymphoid nodules ; 5 and 6, blood-vessels. (Stohr.) 



mucous. The muscular coat is covered externally by a varying 

 amount of loose fibrous tissue. It is composed of two layers 

 of fibres, the outer being arranged longitudinally, and the 

 inner circularly. At the upper part of the oesophagus this coat 

 is made up principally of striated muscle fibres ; they are con- 

 tinuous with the constrictor muscles of the pharynx ; but lower 

 down the unstriated fibres become more and more numerous, and 

 towards the end of the tube form the entire coat. The muscular 

 coat is connected with the mucous coat by a more or less 

 developed layer of areolar tissue, which forms the submucous coat, 

 in which are contained in the lower half or third of the tube many 

 mucous glands, the ducts of which, passing through the mucous 

 membrane, open on its surface (fig. 372). Separating this coat 

 from the mucous membrane proper is a well-developed layer of 



