3iO 



STOMACH AND INTESTINE. 



(Lai. Intestinum tenue,fr Intestin grele,Germ. 

 Duenndarm"). 



The shape of all this portion is cylindrical. 

 Its average length is about 20 feet ; its dia- 

 meter about 1^ inches.* But apart from 

 those varieties in its dimensions which it 

 presents in different individuals, the yielding 

 nature of the tube allows it to be narrowed 

 by artificial extension. While, vice versa, it 

 is just as easily shortened by dilatation. And 

 it is very difficult accurately to estimate those 

 minor degrees of distention to which it is 

 liable. Hence little stress can be laid upon 

 the statement of Cruveilhier, that the small 

 intestine tapers away from the duodenum to 

 near its extremity, where it suddenly dilates 

 to enter the large intestine. 



The small intestine occupies the cavity of 

 the belly. Its commencement, at the pyloric 

 extremity of the stomach, is placed in the 

 right hypochondrium; its termination, in the 

 caecum that begins the large intestine, occu- 

 pies the right iliac fossa, to which this part of 

 the intestinal canal is fixed. The few inches 

 of bowel immediately above this extremity 

 frequently occupy the pelvic cavity. But 

 almost all the intervening portion is so free 

 to move, that each particular point of its 

 length may be found in any part of the ab- 

 domen or pelvis. 



* Trustworthy observations on this point are still 

 to be desired. Meckel states that the length of 

 the whole intestine is from three to ten times the 

 stature. And most authors have been content to fol- 

 low him in estimating its average proportion as six 

 times the height of the body. As 1 presume such a 

 comparison of the two measurements was never in- 

 tended to be more than an aid to the memory of the 

 Anthropotomist, I need scarcely point out its in- 

 herent improbability, as well as the difficulty of 

 establishing a close ratio between a multiple assumed 

 to be so high, and a multiplicand known to be so 

 variable. Besides, differences in the dimensions of 

 the canal are not easih' established, unless their 

 amount is very considerable. For the facility with 

 which, in such a tube, length is convertible into 

 width, forms one palpable source of error, which can 

 only be obviated by a very careful comparison of 

 both the above measurements. The effect of a more 

 or less complete removal of the mesentery is almost 

 as obvious ; and perhaps entitles us to suspect that 

 all such estimates of the length of the separated 

 bowel represent it as somewhat greater than it 

 wou'd be in situ. And we are still more unable to 

 determine that alteration of both dimensions which 

 the simultaneous dilatation or contraction of its 

 two muscular strata would necessarily effect. While 

 it is only after we have either obviated, or al- 

 lowed for, all the preceding causes of inaccuracy, 

 that we can come to any valid conclusion respecting 

 those differences which doubtless obtain in different 

 individuals. 



The statement I have ventured upon in the text is 

 based upon a number of measurements made by my- 

 self. In making these, the healthy intestine was laid 

 upon a board, and spread out to what seemed a proper 

 width, before taking its length. Their number (less 

 than forty) is too small to justify us in regarding 

 their average as a very valid one. They afford 

 no information as to the effect of age or obesity. 

 But they give what is probably a more accurate 

 estimate than that ordinarily adopted by authors. 

 And they agree with an average given by 

 Cruveilhier, as well as with four cases, in which it 

 ceems not unlikely that he adopted precautions 

 similar to those just alluded to. 



T/ie duodenum. That upper part of the small 

 intestine which is directly continuous with the 

 stomach, is distinguished, both from this organ, 

 and from the lower part, by certain peculiari- 

 ties. And though these chiefly affect its exter- 

 nal anatomy, still we shall hereafter find that 

 they are not unaccompanied by differences in 

 the structure of its mucous membrane. Start- 

 ing from the constriction before alluded to, as 

 marking the site of the pyloric valve, the in- 

 testinal tube forms a curve in the shape of a 

 horse-shoe around the head of the pancreas ; 



Fig. 254. 



Shape and arrangement of the duodenum. (Tlie 

 stomach and liver are raised to show the pancreas.) 



st, stomach ; p, its pyloric valve ; /, liver; g, gall- 

 bladder; d, duodenum; 1, 2, 3, its first, second, 

 and third portions; pa, pancreas; h, head of the 

 pancreas, which is received into the concavity of 

 the duodenum ; sp, spleen ; a, aorta, behind the in- 

 ferior transverse portion of the duodenum ; sm, the 

 superior mesenteric artery, in front of it. 



receives the duct of this gland, as well as that 

 of the liver ; and is closely fixed by perito- 

 neum to the posterior wall of the belly. This 

 fixed commencement of the small intestine has 

 been named the duodenum, in consequence of 

 its length being estimated at twelve finger- 

 breadths (SiaSfKaSditTvXov, zwoelffingerdarni). It 

 has also been called the ventriculus succenlu- 

 rialus, or supplementary stomach; a vague 

 term, which was probably based upon an in- 

 accurate notion of its office. 



Beginning at the pyloric constriction, the 

 duodenum proceeds outwards, backwards, and 

 a little, upwards, to the under surface of the 

 right lobe of the liver. It then turns down- 

 wards, and a little inwards, in front of the 

 right kidney; so as often to impress a shallow 

 foi>sa on the hepatic surface in front of that 

 depression which corresponds to this organ. 

 After a short perpendicular course, it finally 

 makes a second bend, by which it regains a 

 horizontal direction, and passes from right to 

 left, and a little upward, in front of the vena cava, 

 the aorta, the right crus of the diaphragm, and 

 the vertebral column. It terminates opposite 

 the left side of the body of the second lumbar 

 vertebra, at a point which corresponds to the 

 commencement of the mesentery. Here the 

 intestine becomes free, and is named the 

 jejunum, 



The length of all this curve, when unfolded, 

 is about ten inches. But for the sake of 



