308 



STOMACH AND INTESTINE. 



the trunk in which they are enclosed ; and it 

 limits, permits, and facilitates those move- 

 ments, which it is chiefly the office of the second 

 to execute. The third is the most important, 

 since it forms the complex secreting and ab- 

 sorbing surface, upon which the functions of the 

 canal mainly depend. Between these three 

 tunics are interposed two layers of areolar 

 tissue ; containing vessels, nerves, and lympha- 

 tics for their supply. The various modifica- 

 tions undergone by these constituents of the 

 tube, in the three segments just distinguished 

 as the stomach, small intestine, and large in- 

 testine, will form the chief features of the fol- 

 lowing description. 



The STOMACH is the widest and most di- 

 latable part of the alimentary canal. 



Its form varies greatly in different indivi- 

 duals. Removed from the body, and mode- 

 rately distended, it generally takes the shape 

 represented in Jig. 240.*; a shape which is 

 often compared to that of a bagpipe, and may 

 be best described as a bent cone, the concave 

 aspect of which is joined by a tube at one- 

 fourth of the distance from its base. In it we 

 distinguish an anterior and a posterior surface; 

 a superior and an inferior border; a right and 

 a left extremity; together with the cardiac and 

 pyloric apertures, by which it communicates 

 with the oesophagus and duodenum respec- 

 tively, and thus becomes continuous with the 

 remaining portions of the digestive canal. 



The description of these different parts 

 will vary, according to the full or empty state 



Fig. 240. 



Stomach and duodenum. The tube has been everted and inflated, and its mucous membrane dissected off, 



so as to show the subjacent muscular coat. 



a g, cardiac orifice; b h, pyloric valve; a e b, lesser curvature, or upper border; g dfc Ii, greater 

 curvature, or lower border. (The dotted lines joining a e, e b, and c h are intended to illustrate 

 the mode in which extreme distention of the organ affects these curves) ; g d, cardiac pouch ; b h c e, 

 pyloric pouch. (The surface to the right of the line which would unite eg represents the oblique, that 

 to the left of this line the circular, layer of the muscular coat of the stomach.) 



of the organ. Thus in the latter con- 

 dition, the stomach is flattened vertically ; 

 so that its anterior and posterior mucous 

 surfaces come into contact, while its upper 

 and lower margins form thin edges, each of 

 which really deserves the title of a " border." 

 But when distended, any transverse section of 

 the organ would be nearly a circle ; and hence 

 its borders and its surfaces disappear by 

 merging into each other. Its uppermost part, 

 however, is still distinguished as the lesser 

 curvature (a, e, I), fig. 242.), and the lower as 

 the greater curvature (g, d,f. c, h). It will 

 be seen that the general concavity of the 

 former curve is especially marked in its first 

 half or two-thirds ; at the end of which part 

 (e) it usually becomes slightly convex. A 

 very shallow notch (r) opposite to this point 

 often divides the greater curvature into two 

 portions ; and the two constrictions together 

 define the commencement of the pyloric pouch 

 (6, h, c, e). The cardiac pouch, or great or 

 splenic extremity (d), lies to the left of the 

 cardia or the cesophageal opening (), beyond 

 which it projects for about three inches. At 

 this aperture the oesophagus dilates gradually, 

 so as to resemble an inverted funnvl. To the 



right of the oesophagus, the stomach expands 

 slightly, and hence reaches its maximum dia- 

 meter at about the middle of the organ (/). 

 Beyond this point it gradually tapers away to 

 the pylorus (/>,/>), where a sudden external 

 constriction marks the site of the valve. 



The dimensions of the organ are even more 

 variable than its form. The author's mea- 

 surements are not sufficiently numerous to jus- 

 tify him in offering them as valid averages; but 

 he has generally found that, in a state of mo- 

 derate distention, its length is about 13 to 15 

 inches, its diameter at the widest part 5, at 

 the pylorus 2, or through the whole organ 4, 

 inches. Hence its total surface would equal 

 about li square feet ; and its capacity about 

 175 cubic inches, or 5 pints. Its weight 

 may be estimated at about 7 ounces. These 

 estimates are a little larger than those of 

 most other anatomists. 



The attachment of the stomach is chiefly 

 effected by the continuity of its extremities 



* This woodcut is so far inaccurate, that the 

 pyloric. constriction is shown more distinct!}' than 

 it could be actually seen in such a view, in which it 

 would bo partially concealed by the backward curve 

 of this part of the stomach. 



