406 



STOMACH AND INTESTINE. 



thus claims a considerable part of the trunk 

 which generally belongs to the thorax. The 

 duodenum is so fixed as scarcely ever to be 

 displaced, except when it is dragged out of 

 its normal position, by displacements of the 

 stomach or small intestine. 



It is in the large intestine that such devia- 

 tions of position are most frequently found. In 

 the coecum, however, they are by no means 

 common ; or if present, are generally limited 

 to a descent of its dependent left extremity 

 into the pelvis. The more frequent displace- 

 ments of the ascending and descending colon 

 seem usually produced by changes, which 

 principally engage the segments that imme- 

 diately succeed them. Thus the transverse 

 colon sometimes appears to be wanting; being 

 converted into a narrow arch, with the con- 

 vexity upwards, and having sides which are 

 no way distinguishable from the ascending 

 and descending colon. The reverse of this 

 state is even more common, in which the 

 arch, instead of being horizontal, has its centre 

 depressed towards the hypogastrium, so as to 

 form an abrupt vertical bend, with the con- 

 vexity downwards. Here the neighbouring 

 ascending and descending segments of the 

 bowel are, as it were, drawn into the increased 

 length of transverse colon, so as to be them- 

 selves greatly shortened. And finally, the 

 displacements of the sigmoid flexure, which 

 are even more common than the preceding, 

 resemble them in the modifications which 

 they impress on the normal length and curva- 

 ture of the tube. Sometimes they merely 

 exaggerate the natural curve of this part ; 

 sometimes they lengthen it at the expense of 

 the descending colon, or even of the rec- 

 tum; and occasionally the curve is, as it 

 were, transferred to the latter bowel. Lastly, 

 the sigmoid flexure is sometimes preceded by 

 a long segment of tube, v\hich carries it over 

 to the right iliac fossa ; where it is so fixed, 

 that the rectum which succeeds it, shares its 

 displacement, is attached to the right sacro- 

 iliac symphysis, and only gains the median 

 line towards the middle of the sacrum. 



The origin of many of these displacements 

 is scarcely at present ascertained. But there 

 is little doubt that they are often produced by 

 tight-lacing, as above alluded to. Such a con- 

 jecture is confirmed by the fact, that they are 

 almost limited to the female sex. They seem 

 to occur most frequently in persons who have 

 borne children. 



We have next to notice a form of accidental 

 displacement, in which the change of situation, 

 though limited in amount, is much more se- 

 rious in its results, leading to an obstruction 

 that is usually fatal. It includes the various 

 kinds of torsion, and the intus-susception or 

 inversion of the canal. 



In the torsion of the intestine, a portion 

 of bowel is more or less twisted, either around 

 its own axis, or around a centre formed by 

 a variable extent of the neighbouring mesen- 

 tery. The parietes of the tube are thus 

 brought into contact with each other, with 

 the effect of completely occluding its calibre. 



In what way this twisting is effected, or why 

 it is not soon effaced by the subsequent dis- 

 tention of the bowel, it would be incompa- 

 tible with the limits of this sketch to inquire. 



In mtiis-susceptioji, the obstruction is ef- 

 fected by the passage of a longer or shorter 

 segment of the canal, with a portion of its 

 adjoining mesentery, into the cavity of the 

 next or following segment. 



The anatomy of this displacement may be 

 best traced by a brief narrative of the steps 

 of its occurrence; at any one of which death 

 may intervene. 



Mobility of the tube is an essential condi- 

 tion of its production. Hence intus-sus- 

 ceptions are generally found in the small 

 intestine, and sometimes in the large intes- 

 tine ; but rarely or never in the duodenum. 



Irregular contraction of the muscular coat 

 seems equally essential to their occurrence. 

 Hence we often find them in dead bodies, as 

 a result of the intestinal rigor mortis. While 

 their occurrence during life can often be 

 traced to a casual diarrhoea, which seems to 

 form at least their exciting cause. 



They are almost invariably produced by 

 the reception of a superior into an inferior 

 segment of bowel. It would therefore seem 

 that they " originate as a kind of perverted 

 peristalsis: that, the longitudinal fibres re- 

 maining quiescent, the intestine is surprized by 

 a transverse constriction, the rapid advance of 

 which hurries the contracting portion into the 

 flaccid and dilated part immediately anterior 

 to itself."* The whole of this process appears 

 to be well illustrated by the ordinary action 

 of the oesophagus, the lower end of which 

 tube undergoes a temporary intus-susception 

 into the stomach at the end of every act of 

 deglutition. -f- 



The way in which the transverse contrac- 

 tion of a segment of intestine furthers intus- 

 susception, receives some illustration by its 

 frequent occurrence in cases where a poly- 

 pifonn tumour is attached by a pedicle or 

 stalk to the interior of the intestine. Here 

 the traction exercised by the stalk of the 

 tumour on the wall of the bowel from which 

 it takes its origin, appears to assist the 

 muscular contraction of the segment which 

 immediately propels the tumour itself, in 

 producing the intus-susception. 



The mechanical obstruction produced by 

 an intus-susception is probably always an 

 indirect result. It is perhaps aided by the 

 obliquity of the received portion, the open end 

 of which is always inclined towards the me- 

 senteric border of the bowel. This obliquity- 

 seems due, partly to the pledget of mesentery, 

 which shares the occupation of the outer or 

 receiving segment of intestine ; partly to the 

 greater distention undergone by the free mar- 

 gin of the bowel above. In large intus-sus- 

 ceptions, the mesentery thus forms a thick 

 strong cord, that not only ties down the 

 bowel by its inner margin, but constitutes the 



* Author. Op. cit., p. 17. 

 f Seep. 311. 



