340 



DISSECTION OF THE ABDOMEN. 



The muscu- 

 lar coat is 

 made up of 



longi- 

 tudinal, 



circular, 



and obliciue 

 fibres. 



The fibrous 

 coat is thin 

 but firm. 



Mucous 

 coat: 



feel and 

 colour ; 



folds ; 



thickness ; 



disposition 

 at pylorus. 



The muscular coat will be laid bare by the removal of the serous 

 covering. Its fibres are imstriated or involuntary, and arranged in 

 three sets, viz., longitudinal, circular, and oblique, in the order 

 mentioned from without inwards. 



The longitudinal fibres (fig. 126, a) are derived from the oesophagus ; 

 they spread over the surface, and are continued to the pylorus and 

 the small intestine. The fibres are most marked along the borders, 

 particularly at the smaller one ; and at the pylorus they are stronger 

 than in the centre of the stomach. 



The circular fibres (fig. 126, 6) form the middle stratum, and will 

 be best seen by removing the longitudinal fibres near the pylorus. 

 They reach from the left to the right end of the stomach, but do not 

 encircle the fundus. At the pylorus they are most numerous and 

 strongest, and form a ring or sphincter (c) round the opening. 



The oblique fibres (fig. 126, e) are continuous with the circular or deep 

 layer of fibres of the oesophagus. On the left and right of the cardiac 



orifice they are so arranged as to form 

 a kind of sphincter (d and e} (Henle) ; 

 those on the left (), the strongest, arch 

 over the great end of the stomach, and 

 spread out on the anterior and pos- 

 terior surfaces, gradually disappearing 

 on them. 



Dissection. Eemove the muscular 

 layers over a small space and the fibrous 

 or submucous coat will appear as a white 

 shining stratum of areolar tissue. This 

 coat gives strength to the stomach, and 

 serves as a bed in which the larger 

 vessels and nerves ramify before their 

 distribution to the mucous layer. If a small opening be made 

 in this submucous coat, the mucous coat will project through it. 

 Finally the stomach should be opened along the lesser curvature to 

 near the pylorus. The finger should be passed through the pylorus 

 to feel its sphincter, and then the incision should be continued 

 through the pylorus and along the convexity of the duodenum 

 to its termination. 



The mucous coat will come into view, but the appearances now 

 described can be recognised only in a recent specimen, or in one 

 well preserved by formalin injection. 



This coat is a softish layer, of a pale rose colour soon after death, 

 in the healthy condition. In the empty state of the stomach the 

 membrane is less vascular than during digestion ; and in infancy the 

 natural redness is greater than in childhood or old age. When the 

 stomach is contracted the membrane is thrown into numerous wavy 

 ridges or rugce, which become longitudinal along the great curvature, 

 towards the pylorus. 



The thickness of the mucous membrane is greatest near the 

 pylorus ; and at that spot it forms a fold, opposite the muscular 



FIG. 127. ALVEOLAR DEPRES- 

 SIONS OF THE MUCOUS MEM- 

 BRANE OF THE STOMACH, 

 MAGNIFIED 32 DlAMETERS, 

 WITH THE MINUTE TUBES 

 OPENING INTO THEM (SPROTT 

 BOYD). 



