FOOD AND DIGESTION. 



351 



THE (ESOPHAGUS on GULLET. 



The (Esophagus or Gullet, the narrowest portion of the alimentary 

 canal, is a muscular and mucous 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 oasophagus is made up of three coats viz., the 

 outer, muscular; the middle, submucous; and the inner, mucous. The 

 muscular coat is covered externally by a varying amount of loose fibrous 







Fig. 248. Transverse section of the human oesophagus, a. Fibrous covering; 6. longitudinal 

 muscular fibres; c, transverse muscular fibres; d, areolor or submucous coat; e, muscularis 

 mucosae; /, mucous membrane, with part of a lymphoid nodule; g, stratified epithelial lining; ft, 

 mucous gland; i, gland duct; m', striated muscle fibres. (V. Horsley.) 



tissue. It is composed of two layers of fibres, the outer being arranged 

 longitudinally, and the inner circularly. At the upper part of the (esoph- 

 agus this coat is made up principally of striated muscle fibres, as they 

 are continuous with the constrictor muscles of the pharynx; but lower 

 down the unstriated fibres become more and more numerous, and toward 

 the end of the tube form the entire coat. The muscular coat is con- 

 nected with the mucous coat by a more or less developed layer of areolar 

 tissue, which forms the submucous coat (fig. 248, /), in which is con- 

 tained in the lower half or third of the tube many mucous glands, the 

 ducts of which, passing through the mucous membrane, open on its sur- 

 face. Separating this coat from the mucous membrane proper is a well- 



