STOMACH AND INTESTINE. 



311 



which is longitudinal : and an internal, which 

 is circular or transverse a general arrange- 

 ment to which even the stomach forms no real 

 exception. Before the discovery of the fibre 

 cell by Koelliker, it was a matter of fruitless 

 speculation, how these unstriped fibres termi- 

 nated; in other words, what was their indivi- 

 dual length. But although this question is of 

 course set at rest, it still remains doubtful, 

 whether the transverse fibres of the alimentary 

 canal return into themselves on completing 

 one circle of the tube, or whether they take 

 a spiral course. The latter view appears to 

 the author much more probable. For some 

 of their bundles often appear to join each other 

 at a very acute angle. And whatever be the 

 precise mechanism of their really co-ordinate 

 contractions, it is clear that, in the longitu- 

 dinal fibres, the direction and progress of con- 

 traction correspond to the axis of the cell : 

 that is, to the line uniting the greatest number 

 of its sarcous particles. While it is equally 

 obvious that, if the course of these transverse 

 fibres were absolutely circular, the peristalsis 

 of the whole stratum they compose would 

 move at right angles to their axes. Such a 

 difference in their contraction would be so 

 unlikely, as to justify our preferring the sup- 

 position of their spiral arrangement. For this 

 would allow of an identity in the contractions 

 of the two strata in this respect. The course 

 of contraction would be axial in both sets 

 of fibres ; but, c&teris paribus, slower (and 

 hence apparently more local) in the far longer 

 bundles of the transverse coils. The spiral 

 currents hereafter alluded to as seen in the 

 contents of the stomach perhaps strengthen 

 this supposition. 



The longitudinal layer of the stomach is de- 

 rived from the similar tunic of the oesophagus. 

 This, on reaching the cardia, radiates on all 

 sides, its bundles becoming thinner as they 

 diverge, and being gradually lost from their 

 decussation and mixture with the various 

 fibres they meet with. But, on the lesser 

 curvature of the organ, they continue much 

 more distinctly, and are often traceable as 

 two or three broadish bundles, to within a 

 short distance of the pylorus. The longitu- 

 dinal layer which covers the pyloric extremity 

 appears not to have any very direct con- 

 tinuity with the preceding. Its constituent 

 fibres arise by scattered bundles at about the 

 middle of the organ, and often first uniting 

 into two broad bands which occupy the cen- 

 tres of its anterior and posterior surfaces 

 they soon form a tubular layer, which pro- 

 ceeds over the pylorus, to join the com- 

 mencement of the duodenum. 



The transverse or circular fibres lie immedi- 

 ately beneath those of the longitudinal stratum; 

 and form what is, on the whole, a thicker, if 

 not a more uniform, layer. To the left of the 

 cardia its rings are very few and indistinct: 

 their places being taken by those of the third 

 or oblique layer. But from the right of 

 this orifice it continues towards the pylorus 

 with a constantly increasing thickness; until 

 finally, reaching the margin of this valve (fig. 



243.), it is inflected towards the axis of th e 

 stomach by a rather steep and sudden curve, 

 which presents an almost vertical surface 



Fig. 243. 



Longitudinal section of tfie alimentary canal at the 

 junction of the stomach and duodenum, to show the 

 thickness of the pyloric valve. 



*, pyloric sac of the stomach ; d, commencement 

 of the first portion of the duodenum ; j9, pylorus, 

 formed by a thickening of the transverse layer of 

 the muscular coat of the stomach. 



towards the duodenum. Those of the trans" 

 verse fibres which lie nearest to the left ex' 

 tremity are somewhat less regularly transverse. 

 Hence some of them decussate slightly with 

 each other, while others, which pass down- 

 wards from the right margin of the cardia, are 

 directed somewhat obliquely towards the left 

 extremity of the organ. 



The third or oblique layer lies more deeply 

 than the two preceding, and is therefore best 

 seen by everting and inflating the stomach, 

 and carefully removing its mucous membrane. 

 Where the oesophagus enters the stomach, 

 the transverse fibres of its left margin are 

 so close to a flattened bundle of fibres, 

 which occupies the notch (g,fig. 240.), limiting 

 the cardiac pouch, that the two are visibly 

 continuous. The right or thickest part of 

 this flattened band passes obliquely downwards 

 towards the right side, soon breaking off from 

 the termination of the oesophagus ; and from 

 hence it continues across the transverse layer 

 just described, to reach the greater curvature, 

 where the similar layers from both surfaces of 

 the organ are reflected into each other. Its 

 usually well-defined margin occupies and 

 indeed forms the notch (c,fig. 240.). The 

 posterior or thinner part proceeds, not only 

 from the depression (g,./%. 240.) on the left of 

 the cardia, but also from the neighbouring upper 

 border of the great extremity; and its more 

 vertical fibres are also continued downwards 

 to the lower border of the stomach, where 

 they meet, so as to complete the circuit of 

 the cardiac pouch. 



Movements of the stomach. That there is 

 an intimate connection between the oesophageal 

 and gastric movements, is only what might be 

 expected from that visible continuity of their 

 muscular coats which has just been alluded to. 

 Thus, at the close of each act of deglutition*, the 

 lower fibres of the oesophagus contract with such 

 force, as not only to obliterate the cardiac aper- 

 ture, but even to cause the mucous membrane 

 of this part to project into the cavity of the 



* For a description of the act of deglutition see 

 the articles " (ESOPHAGUS" and " PHARYNX." 



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