INTEST-INES. 



Its conneftion to the pancreas, and receiving the fecreted 

 fluid of that gland and the liver. Its figure is perhaps lei's 

 regularly cylindrical, and there are fome differences in the 

 mucous membrane. 



The artei-ics of the duodenum are derived from the gaftro- 

 duodenal branch of the hepatic, and from the fuperior me- 

 fenteric : the veins joi '. fome of the trunks, which contri- 

 buted to the formation of the vena portarum. The abforb- 

 ing vcflels pafs to the glands at the root of the mefentery. 

 The nerves come from the cxliac ganglia. 



Second Divlfion of the fmall Intefi'mts — This part of the 

 canal, which is very loofe and moveable, forms numerous 

 turns, and its convolutions fill up the fpace between the 

 bladder and uterus below, and the lar^e iuteftine above and 

 at the fideS : the latter part alnioft encircles the fpace in which 

 this divilion of the canal lies. As the cascum and the fig- 

 moid flexures of the colon do not touch below, the fmall i:i- 

 tefline defcends in their interval, in greater or lefs quantity, 

 into the pelvis. The umbilical and hypogallric regions of 

 the abdomen are chiefly occupied by thefe convolutions : 

 which accommodate themfclvcs, by their perfetl mobility, 

 to the numerous changes produced in this fpace. A dilUnded 

 ftate of the Uomavh caufes them to defcend : when the 

 bladder, refluni,and uterus are empty, much of the inteftine 

 is found in the pelvis ; but when thefe organs, and particu- 

 larly the latter, are diilended, the inteibne afcends : in a 

 word, it pafi'es into any fpace that remains open for it. The 

 tranfverfe arch of the colon bounds the fpace occupied by 

 the fmall intet'.ine above : the lumbar portions of the la-ge 

 intetline, fixed to the back of the abdomen, allow the con- 

 volutions to pafs in front of them, and to correfpond imme- 

 diately to the abdominal panetes. The latter limit and con- 

 fine it in front, and are fepaiated from it only by the great 

 omentum. 



A broad fold of peritoneum, called the mefentery, con- 

 neftsit in its fituatir.n to the abdomin;U cavity ; this conlifls 

 of two layers, which receive the inteftine b-twcen them, and 

 give it a fmooth external coat. Tliis fold is attached to the 

 back of the abdomen, in an oblique line, extending from 

 the left lumbar to the right iliac regions : here it is about 

 fix inches broad. It expands fo confiderably as to be broad 

 enough on the oppoGte or front margin, to be attached to 

 the whole length of the jejunum and ileum. In confcquence 

 of this great breadth of the anterior part, the mefentery 

 itfelf, in this fituation, forms a va!l number of loi;giti;dii!al 

 {•laits. The ftat furfaces of the mefentery are fmooth, and 

 coiitigiious to the inteftinal convolutions. Tl'.e depth of the 

 mefentery, from its pollcrior or fixed, to its anterior or 

 kiofe edge, is greateit in the middle, and gradually dimi- 

 niihcd towards either end. Its ilrufture a-id attachments 

 are fuch as to preferve the inteilinal convolutions in a certain 

 relative pofition, and at the fame time to allow in the whole 

 a coifKlerablc liberty of motion ; it prevents the inteftines 

 aifo from becoming entangled in the motions of its individual 

 parts. 



It is compofed of two membranous layers, produced 

 from the peritoneum. The latter membrane, after lining 

 the pollerior and right portion of the abdomen, when it ar- 

 rives at the root of the irieientery, is reflefted from behind 

 forwards, infteadof being continued to the left fide. That, 

 wliich has lined the poflerior and left divilion of the cavity, 

 is alfo reflefted from behind forwards, in (lead of paffing in 

 front of the vertebra;. Thefe laminas, turned towards each 

 other, form the two furfaces of the mefentery ; they fepa- 

 »ate at the intelline, and leave a cylindrical tube, in which 

 that caiul is contained. They are connected by a layer of 

 cellular lae.nbrane, containing more or lefs feet, and the ar- 



teries, veins, and nerves of the jejunum and ileum, as well as 

 the ladeal vefTels and their glands. 



The inteilinal convolutions have no fixed fituation, but 

 are formed, deflroyed, and renewed, carried upwards, 

 downwards, S:c. according to the general or particular mo- 

 tions of the canal ; yet the concavity of each turn is always 

 at the mefenteric edge, and its convexity at the loofe mar- 

 gin of the gut. The very loofe attachment to the fides 

 of the cavity, and the apparently irregular order in 

 which the convolutions of the intellines are difpofed, feem 

 at firll fight to prevent us from affigning any particular di- 

 reftion to this part of the canal. But if we put out of the 

 queilion the great mafs of the turns, and examine the parts 

 where it begins and ends, and conlider at the fame time the 

 direftion of the mefentery, we (liall find that the canal alto- 

 gether pafles obliquely from above downwards, and from the 

 left towards the right iide. It begins in faft on the left fide 

 of the tranfverfe mefocolon below the fuperior mefenteric 

 veliels, and it terminates in the right iliac region, wliere it is 

 fixed to the fide of the caecum. 



A tranfverfe feftion of the inteftine prefenis an elliptical 

 area ; of which the fmaller circle correfponds to the mefen- 

 tery, and the larger to the loofe edge of the intelline. Confi- 

 dered in its whole length, the nieienteric or attached edge is 

 concave ; the loofe margin convex. The fmall trunks of the 

 blood- veffels enter on the former ; their minute ramilications, 

 and the fine origins of the abforbents, are obfervcd on the 

 latter. 



Sometimes fmall b'ind procefTes, or appendices, varying 

 in length from a few lines to three or four inches, are con- 

 nected to the fmall inteftine. It is very uncommon to fee 

 more than one in a fubjedt. They are cylindrical or coni- 

 cal towards the extremity, communicate freely with the rell 

 of the canal, and completely agree with it in ftructure. 

 There can be no doubt that they are originally formed parts, 

 and not produced by any morbid exteniiou of the inteftinal 

 parietes. They are often mentioned under the name of di- 

 verticula. 



When moderately diftended, the inteftine meafures more 

 than an inch at its largelt diameter, and lefs at the 

 fmalleft. When it is completely diftended, the figure is 

 circu'ar. 



The coats are thinner than in the ftomach or in the large 

 inteftine : they are thickeft at the beginning, and grow gra- 



Jly th 



to the end. They appear proportion 



tliieker, when the inteftme is in a concrafted ftate. It is 

 more fleftiy, elallic, and dark coloured ; in a word, firmer 

 and thicker in perfeftly healthy men than in women or vale- 

 tudinarians. When it'is aiTerted that tiie canal is fo many 

 times the length of the body, we only mean to give a gene- 

 ral notion of its extent : for there is no relation between llie 

 (lature of individuals and the volume of their, gallris. 

 vifcera. 



The diftin<!tk)n of the jejunum and ileum is quite arbitrary : 

 there are no marks fliewing the termination of one, and the 

 beginning of the other:, but the two ends of the c.inal differ 

 obvioully in fcveral points. Window gives the former name 

 to the upper two-fifths of the tube, and. the latter to the 

 lower three-fifth"!. 



Orgam-z,atioti of the fmall ItilefUne. — It coniifts, like the fto- 

 mach, of three diilinct ilrata or coats, connedted by cellular 

 fubftance : thefe are moft clearly feen on the cut edge of the 

 part, after a fimple incillon, when the difference of colour 

 and denfity enables us to diftinguifli them ealily. Boiling 

 and maceration in proof fpirit rendtir the difFcCtion of the 

 inteftinal coats more eafy. 



The liril or external coat is aferous membrane, confifting 



of. 



