442 



THE ALIMENTAKY CANAL. 



[CH. XXVII. 



Structure. The stomach is composed of four coats, called 

 respectively (i) an external or peritoneal, (2) muscular, (3) sub- 

 mucous, and (4) mucous 

 coat ; with blood-vessels, 

 lymphatics, and nerves 

 distributed in and be- 

 tween them. 



( i ) The peritoneal coat 

 has the structure of serous 

 membranes in general. 

 (2) The muscular coat 

 consists of three sepa- 

 rate layers or sets of 

 fibres, which, according 

 to their several directions, 

 are named the longitu- 

 dinal, circular, and ob- 

 lique. The longitudinal 

 set are the most super- 

 ficial : they are continuous 

 with the longitudinal 

 fibres of the oesophagus 

 and spread out in a di- 

 verging manner over the 

 cardiac end and sides of 

 the stomach. They ex- 

 tend as far as the pylorus, 

 being especially distinct 

 at the lesser or upper 

 curvature of the stomach, 

 along which they pass in 

 several strong bands. The 

 next set, the circular or 

 transverse fibres, are most 

 abundant at the middle 

 and in the pyloric portion 

 of the organ, and form 

 the chief part of the thick 

 projecting ring of the 

 pylorus. They are con- 

 tinuous with the circular 



layer of the intestine. The deepest set of fibres are the oblique, 

 continuous with the circular muscular fibres of the oesophagus: 

 they are comparatively few in number, and are found only at the 



Fig. 373. From a vertical section through the mu- 

 cous membrane of the cardiac end of stomach. 

 Two glands are shown with a duct common to 

 both, a, duct with columnar epithelium be- 

 coming shorter as the cells are traced down- 

 ward ; n, neck of gland tubes, with central and 

 parietal cells ; 6, f undus with curved csecal ex- 

 tremity the parietal cells are not so numerous 

 here. (Klein and Noble Smith.) 



