Paper - Studies of the intestine and peritoneum in the human foetus - part 6
|Embryology - 3 Jul 2020 Expand to Translate|
|Google Translate - select your language from the list shown below (this will open a new external page)|
العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt These external translations are automated and may not be accurate. (More? About Translations)
|A personal message from Dr Mark Hill (May 2020)|
|contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!|
Reid DG. Studies of the intestine and peritoneum in the human foetus: Part VI. (1913) J Anat Physiol. 47(4): 486-509. PMID 17232976
|Historic Disclaimer - information about historic embryology pages|
|Embryology History | Historic Embryology Papers)|
- 1 Studies Of The Intestine And Peritoneum In The Human Foetus
- 1.1 Part VI. The Duodenum, with a note on the Subdivision of the Abdominal Cavity by Peritoneal Folds and Adhesions
- 1.2 The Retro-Duodenal Fossae
- 1.3 The Retro-Pancreatico-Duodenal Recess
- 1.4 Chiefly Concerning the Development of the Duodenum
- 1.5 The Relations or the Peritoneum or the Intestinal Loop to the Duodenum
- 1.6 The Special Relations of the Duodenum
- 1.7 The Genesis of Certain Folds of Peritoneum in Relation to the Duodenum
- 1.8 The Subdivision of the Abdominal Cavity by Peritoneal Folds and Adhesions
Studies Of The Intestine And Peritoneum In The Human Foetus
By Douglas G. Reid, M.B., Ch.B. Edin., B.A. Trin. Coll. Camb.,
Demonstrator of Anatomy in the University of Cambridge.
Part VI. The Duodenum, with a note on the Subdivision of the Abdominal Cavity by Peritoneal Folds and Adhesions
Synopsis of the Present Study - The retro-duodenal fossae are ﬁrst considered; then the retro-pancreatico-duodenal recess; the development of the duodenum ; the relations of the peritoneum of the intestinal loop to the duodenum; the special relations of the duodenum; and the genesis of certain folds of peritoneum in relation to this part of the bowel. Lastly, I consider points of surgical interest in connexion with the natural subdivision of the abdominal cavity into compartments or recesses.
Preliminary Remarks - Cleland (see the Journal of Anatomy and Physiology, vols. i. and iii.) was chief amongst those who in this country advocated the displacement theory. He speaks of the duodenum “pushing its way underneath the peritoneum of the parieties”; for “ other viscera growing faster are thought to pull it (the meso-duodenum) away and appropriate it” (Brockway in Gray's Anatomy, 1897). He regards the left half of the transverse colon as being formed from “the terminal intestine” (the part of the large intestine which extends from the colon at the splenic ﬂexure (see ﬁg. 6) to the proctodaeum (Jonnesco) ). He states that, “as far as is at present known, the adhesion of serous surfaces only occurs as the result of pathological changes.”
At first, indeed, it may appear diﬂicult to see how, as ﬁrst asserted by His and Toldt, the still mesial splenic flexure of an embryo 25 mm. long (see ﬁg. 6) can gain the position it occupies in a foetus 37 mm. long (see ﬁg. 8).‘ In this country the wheels of the displacement theory were still further sunk in the ruck by the writings of Bruce Young, Lockwood, Treves, and others.
Byron Robinson (Journal of Anatomy and Physiology, 1899, vol. xxxiii.) discusses the two “theories” (Toldt’s and other) without prejudice; and gradually British authors have been coming to regard the adhesion “theory” as the one which more probably expresses the truth.
- 1 According to Flower (Medical Times and Gazette, 1872, vol. i.), the whole of the transverse colon is erived from the terminal intestine.
Behind the head of the pancreas lies the fascia described by Treitz (see ﬁg. 9).
In front of the head of the pancreas there is also a layer of fascia described by Toldt (“the pre-pancreatic fascia ” of Fredet, see ﬁgs. 5, 9).
No attempt has been made by those who advocate the displacement theory to account for these fascias.’ One can hardly doubt (see ﬁg. 5) that they represent the meso-_duodenum. I have frequently demonstrated the fascia of Treitz. So compact a layer may it form in the adult as well as in the foetus, that it can readily be mistaken, at ﬁrst, for normal endotheliumcovered peritoneum if the dissection to expose it has not been watched.
The prostato-peritoneal aponeurosis of Denonvilliersl also represents the connective element of peritoneum (cf. ﬁg. 6 in Part IV. of my “Studies,” Journal of Anatomy and Physiology, vol. xlvii.).
But if any doubt could be expressed, I have, apart from all this, given numerous illustrations of the_ truth of the statement" (which therefore ceases to express a “theory ”) that two nolrmal endothelial surfaces of peritoneum can adhere to one another.
Mall? states that it has been customary to call his second and third loops of small intestine (his third loop corresponds to loop A in ﬁg. 6, the part there named “duodenum” being his ﬁrst loop) the duodenum. “. . . more mature consideration of models convinced me that loops 2 and 3 are ﬁnally transferred to the left side of the body to form the upper part of the jejunum.”
How, then, is the mesentery at its root attached to the fourth (ascending) portion of the adult duodenum ?
I have drawn attention to how certain folds of peritoneum may arise, and have pointed out the particular variations of the small and large intestine which result from displacement or from resistance to growth in certain directions.
Treves has attempted to explain the origin of the inferior duodenal fold. His explanation involves the duodenum being “drawn between the layers of its own meso-duodenum.”
One must try, however, to determine how physical forces really do operate in the production of certain of the peritoneal folds; for even if this particular fold be present in “nearly all mammals,” it would, of course, be a complete mistake “to think that ‘heredity’ will build up organic beings without mechanical means.”
- 1 “ En arriere de la prostate, entre les vésicules séminales et le rectum, existe une couche membraneuse bien distmcte, que j’appelle 1-ostato-péritonéale-—par son bord postérieur, elle adhere a cette portion du péritoine qui escend entre la vessie et le rectum” (Denou villiers, quoted by Proust, La Prostatectomie, p. 160).
- 2 The Johns Hopkins Hospital Bulletin, Nos. 90-91, September—October 1898.
The Retro-Duodenal Fossae
The retro-duodenal fossae which I shall now describe may be tabulated as follows : — (1) The retro—pancreatico-duodenal fossa. (2) The superior retro—duodenal fossa. (3) The intermediate, middle, or lateral retro-duodenal fossa. (4«) The inferior retro-duodenal fossa.‘
The Retro—panc'reatico—duodenal Fossa. — This fossa (see ﬁgs. 1, 2) was found by me in a full—time foetus. It is bounded in front by the ﬁrst and second portions of the duodenum, and by the head of the pancreas; behind, by the parietal peritoneum in front of the inferior vena cava. On the right it is closed in by the duodeno-renal ligament and the genito—mesenteric fold. It extends towards the left as far as the aorta, and downwards as far as the upper border of the third part of the duodenum. It opens above into the vestibule of the lesser sac of peritoneum, and into the greater sac at the foramen of Winslow. It results from the conversion into a fossa of the retro-pancreatico-duodenal recess presently to be described.”
The Superior Retro-duodenal Fossa. — This fossa (see ﬁg. 2) was found by me in an adult body dissected at Cambridge several years ago. It lay behind practically the Whole of the fourth portion of the duodenum. Its oriﬁce, situated opposite the duodeno-jejunal ﬂexure, was directed upwards and bounded on the sides by the free margins of two folds of peritoneum which passed from the parietal peritoneum and the mesocolon at its root. Its oriﬁce thus rather resembles that of the duodeno-jej unal fossa described by Jonnesco in 1889, and situated “au niveau de 1’angle duodéno-jéjunal, entre son dos et la racine du mésocolon transverse.”
The Intermediate Retro-duodenal Fossa.—This fossa (see ﬁg. 2) was found, well marked, by me in ﬁve out of twenty of the 12- to 22—cm. foetuses specially examined. It lies behind the fourth portion of the duodenum.
Its oriﬁce, directed towards the left, is bounded above by the inferior mesenteric vein and the superior duodenal fold; below, by the inferior duodenal fold. The depth of the fossa may equal, but never exceeds, the diameter of the part of the duodenum to which it is related ('i.e. the fossa never passes behind the head of the pancreas). I have found it, equal in depth to the diameter of the fourth portion of the duodenum, in full—time foetuses; and have noted similar, but usually rather shallow, intermediate retro—duodenal fossee in adult bodies.
- 1 Discovered by J onnesco in 1893, and described by him as “ the retro-duodenal fossa.”
- 2 I have only recently begun to look for this fossa in the adult. It certainly appeared to have been present to a slight de ree in a body dissected at Cambridge, Lent Term, 1913. But, unfortunately, the dissectors Tied unconsciously enlarged it in a. downward direction before I saw the exact state of affairs.
Fig. 1. The arrangement of the peritoneum in relation to the duodenum of a full-time foetus is accurately represented. The great omentum is not figured. The interrupted line indicates the extent of the retroduodenal fossa present between the head of the pancreas and the inferior vena cava. The line of the aorta. marks its extent towards the left. The arrow indicates the oriﬁce of the fossa. The peritoneum of the intestinal loop has not fused down over the anterior surfaces of the ﬁlst, second, and third portions of the duodenum. The sheet of peritoneum (A, A) is continued from it, however, over the anterior surface of the seconul part of the duodenum, into the duoxleno-renal ligament and genito-mesenteric fold. These sheets are all continuous. It, is noteworthy that the genito-mesenteric fold is attached to the lowest part of the duodenum.
The fold which contains the hepatic artery, and which forms part of the septum bursarum omentalium, represents (Swaen) meso-duodenum from which the duodenum has retracted. The upper free edge represents the upper border of the meso-duodenum. “ Le transport de l’estomac, sa saillie si prononcéc dans la moitié gauche dc la cavité abdominale, a entrainé dans cette direction la. premiere portion du duodenum qui l11i fait suit, 1’a inclinée vers la gauche, l’a fait sortir du méso duodenum” (Swaen, p 164, Bibliographic Anatormque, tome vii., 1899). The adhesion of the posterior surface of the duodenum (as well as that of the stomach) to the transverse mesocolou is therefore, of course, secondary.
In this specimen the appendix and meso-appendix do not adhere to the genito-mesenteric fold. The mesenteric border of the meso-appendix passes (along the line of a branch of the artery to the appendix) towards the mesenteric border (the anterior part of which lies along the line of the ileac branch of the ileo-colic artery) of the genito-mesenteric fold. but fails to reach it by a distance of 4 mm. (of. ﬁg. 11).
Fig. 2. The four retro-duodenal fossae are shown. The duodenum is represented cut at its junction with the jejunum. The arrows indicate the oriﬁces of the fossm (represented by interrupted lines and stippling).
(1) The lower limit of the retro-pancreaticoeduodenal fossa (seen by me in a full-time foetus) whose entrance is at A.
(2) The lower limit, approximately, of the retro-duodenal fossa (seen by me in the adult) whose oriﬁce is at D; and the right limit of the retro-duonlenal fossa (seen by J onnesco in the adult) whose oriﬁce is at B.
(3) The lower limit of the retro-duodenal fossa (seen by me in the adult) whose oriﬁce is at E; and the lower limit of the retro-duodenal fossa (seen by me in the foetus, and similar to the fossa I have met with in the adult) whose oriﬁce is at D.
Direct adhesions of the duodenum to the parietal peritoneum may take the place of the duodenal folds and bound the oriﬁce of the fossa.
Thus, in an adult (dissected at Cambridge, Lent Term, 1913), the whole of the posterior surface of the fourth part of the duodenum was free. A distinct retro—duodenal fossa in this case, however, only existed below (see ﬁg. 3). It extended towards the right nearly to the root of the ileo-colic artery, and was bounded on the left by a direct adhesion of the duodenum to the parietal peritoneum.
Again, the whole of the posterior surface of the fourth portion of the duodenum may be found free from adhesions without the formation of any fossa. Thus, in an adult, the fourth part of the duodenum, which was soldered down simply along its right border, could, to a certain extent, be made to swing backwards and forwards as on a hinge.
Fig. 3. The arrow indicates the oriﬁce of the fossa.
When the posterior surface of the duodenum is free, jejunum may get in behind it and place itself in contact with the head of the pancreas at the left part of its circumference. This is seen in a 17-cm. foetus. Here the jejunum descends from the duodeno-jejunal ﬂexure and, at a peritoneal fold resembling the inferior duodenal, makes a bend and passes upwards behind the fourth part of the duodenum. Here it lies in contact with the peritoneum covering the superior mesenteric artery and the left part of the border of the head of the pancreas. It comes into contact with the inferior surface of the body of the pancreas, and forms a ﬂexure in the position normally occupied by the duodeno—_jejunal. It was ﬁrmly wedged in between the duodenum and the pancreas, but did not adhere to either. This is the nearest approach towards the development of a retroduodenal hernia that I have seen. A hernial sac might readily have been formed by the secondary formation of peritoneal adhesions, pathological or other.
Fig 4. Fetus 17 cm. long. The jejunum immediately succeeding the duodenum passes downwards and then bends upwards behind the fourth portion of the duodenum. It comes into contact with the inferior surface of the body of the pancreas, and here forms 9. ﬂexure which corresponds in position to the normal duodeno-jejunal ﬂexure. The short descending part of the jejunum adheres along its right border to the duodenum, and to the parietal peritoneum down to the fold of peritoneum. Except for this, it is free, as is the rest of the jejunum.
I have noted apparent absence of the fourth part of the duodenum in an adult.‘
- 1 I only saw this case, however, after the peritoneum had been subjected to some handlin ; and, as the parts were unusually soft, it is possible that if the fourth portion of the duo enuui had been unusually free it might have been dragged downwards. As in the other case referred to, the disscctors were unconscious of having done any mischief.
“ The Retro-duodenal Fossa” of Jonnesco.‘—In View of the retroduodenal fossae which I have described, I propose to call this fossa the inferior retro-duodenal fossa, a name which I understand has already been suggested for it. Any fossa in relation to the duodenum must, of course, be of interest
from a surgical point of view. “J’ajouterai seulement qu’elles out une grand importance practique, car elles sont le siege le plus habituel des hernies internes rétro-peritoneal dont j’ai pu réunir un nombre respectable
Fig. 5. Longitudinal section (u. little to the right of the vertebral column) of a foetus 17 cm. long.
Note the recess, containing the caudate lobe (process), behind the pancreas, and the relations of the right suprarenal body.
The Retro-Pancreatico-Duodenal Recess
When well developed, this recess (see ﬁg. 5) lies behind the ﬁrst and second portions of the duodenum and the head of the pancreas in relation to these parts. It may descend almost to the third part of the duodenum. I ﬁrst observed it, well marked, in a 17-cm. foetus (see ﬁg. 5).
1 This fossa ascends behinrl the fourth portion of the duodenum to the iluodeno-jejunal ﬂexure. It is related to the third part of the duodenum to the (approximate) extent shown in ﬁg. 2, and lies in front of the aorta. Its oriﬁce looks downwar s.
2 It is known that'bowel may protrude into the foran1en of Winslow. It is therefore possible that a piece of intestine could get into a persistent retro- ancrea.tico~duodenal recess or fossa. Inﬂammation might also extend to the up er part 0 the head of the pancreas should intlammator effusions, from the stomach or uodenum especially, collect in such a recess. One shoul also remember that “au niveau de la portion supérieure [of the duodenum] la circonférence [of the head of the pancreas] présente un prolongement tantét it peine indiqué, tantot assez développé pour (lepasser la face postérieure du duodenum; c’est le prolongement supérieur ou rét1'odu0dé-nal” (Charpy in Poirier’s Anatomy, 1905, vol. iv. p. 822).
As in the 20-cm. foetus, a ﬁgure of which as seen in mesial section is given in Part IV. of my “Studies,” the pylorus, in this foetus, is placed opposite the disc between the eleventh and twelfth dorsal vertebrae; and the third portion of the duodenum, in the middle line, lies opposite the disc between the ﬁrst and second lumbar vertebrae. The recess descends to a distance of 1 mm. from the third part of the duodenum.
Lying in this recess, between the duodenum and head of the pancreas in front and the inferior vena cava and the right suprarenal body behind, is a process of the caudate (Spigelian) lobe.
The anterior wall of the recess is of course continuous above with the postero—external surface of the fold which contains the hepatic artery. This fold represents a part of the meso—duodenum (see footnote, ﬁg. 1).
The retro-pancreatico—duodenal recess is also present, well marked, in an 11-cm. foetus. Here it descends behind the ﬁrst part of the duodenum, and behind the upper half of the head of the pancreas and an exactly corresponding part of the second portion of the duodenum. Its posterior wall is formed by a small part of the right kidney in addition to the right suprarenal body and the inferior vena cava.
The recess is also seen in a 20-cm. foetus, but is related to the head of the pancreas only to a slight extent. I have since studied it in other foetuses.
In many there is a recess lying simply behind the ﬁrst portion of the duodenum without coming into direct relation with the head of the pancreas. But,I am inclined to think that the caudate lobe (prdcess) of the liver, as it lies in this recess, .comes into contact with the head of the pancreas more frequently than I at ﬁrst thought. Unless a section be made, in a downward direction, through the ﬁrst part of the duodenum and the head of the pancreas, the true relations of the recess may readily be overlooked.
In a full-time foetus there is a retro-pancreatico-duodenal recess which descends behind the ﬁrst portion of the duodenum and the upper part of the head of the pancreas. It also descends, in front of the right suprarenal body, behind the second portion of the duodenum in its upper half. The caudate lobe of the liver, although coming into contact with the upper part of the head of the pancreas, does not descend to the bottom of the recess (of. ﬁg. 5). The anterior and posterior walls of the lower part of the recess thus come into contact with one another.
The retro-pancreatico-duodenal recess,‘ which should be looked for in the adult, is present in a 37-mm. foetus; and in it was lodged a portion of the liver. This I removed, exposing the smooth parietal peritoneum which forms the posterior wall of the recess.
- 1 It is best to retain this name, even if the recess do not come into direct relation with the pancreas.
In a 25-mm. embryo the duodenum forms a small loop which lies in a plane markedly transverse (see ﬁg. 6). The liver lies in contact 'with the whole of the upper surface of this loop.
As the liver becomes relatively reduced in size the duodenum is pushed into a more frontal plane, and a deﬁnite recess is formed. This tends to become smaller and smaller, the meso—duodenum fusing with the parietal peritoneum from below upwards, until ultimately the peritoneum covering the posterior surfaces of the ﬁrst and second portions of the duodenum and head of the pancreas may be completely soldered down. Should the second part of the duodenum alone become adherent to the parietal peritoneum, or to the left surface of the genito-mesenteric fold (see ﬁg. 1), the retro—pancreatico—duodenal fossa is of course formed. Although the recess be present, the mesentery of the intestinal loop has already adhered to the anterior lamina of the meso—duodenum within the duodenal loop of the 37-mm. foetus (see ﬁg. 8, “secondary root—area ”).
In the 25-mm. embryo intestinal torsion is still incomplete (see ﬁg. 6).
In association with the recess in the larger foetuses, the colon, passing from the front of the right kidney, has to course markedly forwards upon the second portion of the duodenum to reach the ﬁrst portion of the duodenum and the region of the pylorus (see ﬁg. 5). All three structuresduodenum, pancreas, and transverse colon—are propped forwards, as it were, by the caudate lobe of the liver. The posterior surface of the head of the pancreas looks decidedly upwards as well as backwards (see fig. 5).
Chiefly Concerning the Development of the Duodenum
Mall has already drawn attention to the large size of the embryonic duodenufn.
In my 25-mm. embryo it is seen that the ornphalo-mesenteric vessels pass behind a portion of the alimentary canal (see fig. 6, “duodenum ") ; and one can have little doubt that this at least is part of the duodenum. From the point where these vessels come into this relation with the bowel, the intestine passes markedly backwards towards the posterior (dorsal) abdominal wall, and, bending inwards to some extent, comes into contact with the mesial mesentery at the neck of the intestinal loop. This inward bend is well shown in Mall’s ﬁg. 10 of a 28-mm. foetus.
The intestine now passes forwards and becomes continuous with Mall’s third loop (loop A in ﬁg. 6).
The part which thus passes forwards into A forms with the part that passes backwards a loop, the convex surface of which looks backwards and also inwards (see “ﬁg. 6); and at the summit of the curve the small intestine actually adheres, just abovethe splenic ﬂexure, to the right surface of the mesial mesentery at the neck of the intestinal loop.‘
FIG. 6.-—-Embryo 25 mm. long dissected to show the intestinal loop. The head is represented more erect than is normal ; and the trunk has been somewhat straightened. Loop A overlaps the om halo-mesenteric vessels; and the parts of the small intestine in front of the knifeblade :3 so meet in front of these vessels. The omphalo-mesenteric vessels, which lie in a ridge of peritoneum, cross in front of loop D ; and this loop has a limb on each side of these vessels. The appendix is already distinguished by its small diameter. The splenic flexure lies immediately below the stomach in the middle line. The root of the mesentery of the terminal intestine is still mesial. There is no Meckel’s diverticulum. The anterior surface of the large stomach looks upwards as well as forwards Studies of the Intestine and Peritoneum in the Human Foetus 497
It is jammed against this mesentery by the large liver. The part of the small intestine which extends backwards and inwards and is crossed by the vitelline vein is without doubt the duodenum. It is in the median line at its posterior extremity; and this is relatively ﬁxed in position. Therefore, as the duodenum elongates, a more pronounced loop, concave towards the left, is formed.
Already its ﬁrst, second, and third parts are distinguishable.
I have already noted that it lies, with part of the liver directly above it, in a plane which is markedly transverse (horizontal). The manner in which the retro-pancreatico-duodenal recess is deﬁnitely formed has also been indicated. .
But the fourth (ascending) portion of the duodenum has yet to be formed.
The small intestine now begins to work its way under the large, moving about an axis which passes from the median posterior extremity of the duodenum to the caecum, still in the umbilical oriﬁce of my 37-mm. foetus.
This movement has progressed to a considerable extent in this foetus
‘ (see ﬁg. 7).
The splenic ﬂexure has now passed as far to the left as it can (see ﬁg. 8). The left part of the transverse colon is now formed, and the terminal intestine passes downwards, and then downwards and inwards, skirting the right margin of the left testis (see ﬁg. 7). The root of its mesentery is still mesial, however. ‘
The small intestine appears to have pressed the mesentery of the colic portion of the intestinal loop upwards and backwards against the mesoduodenum, to the whole of which, within the concavity of the duodenal loop, it now ﬁrmly adheres, although the serous surfaces of the duodenum are still free. Thus is formed the secondary root-area (see ﬁg. 8).
In the full-time foetus (see ﬁg. 1) the fusions of the peritoneum in relation to the meso-duodenum have been arrested at a stage not much more advanced than this. A genito-mesenteric fold has developed which takes the place of the root of the mesentery and also anchors the duodenum.
The colon has gone on growing, and the caecum lies in the right iliac fossa. The left part of the transverse colon is formed, and the root of its mesentery is practically in the position it occupies in the adult.
- 1 Only the examination of more material can determine if this occur normally. Here, again, there can be absolutely no doubt that two normal endothelial surfaces of peritoneum had adhered to one another.
The great omentum, adhering to the colon, helps to support this to the right of the meso—duodenum (“secondary root-area ”).
In the 37-mm. foetus the upper part of the jejunum, having now worked its way to the left, is already directed upwards to form a short fourth portion of the duodenum (see fig. 7). It is fused along its right border to the peritoneum of the intestinal loop Where this adheres to the mesoduodenum along the inner part of the circumference of the head of the pancreas. Its mesenteric border now becomes the upper part of the root of the mesentery.
FIG. 7.—Foetus 37 mm. long, 6. The interrupted lines in A indicate the position of the lower border of the liver and of the umbilical oriﬁce. The upper border of the oriﬁce lies 0 posite the lower border of the liver. In B the interrupted line indicates the course of the (111 enum. The parts of the intestine and mesentery which correspond are indicated by ﬁgures. The stomach and first part of the colon (passing backwards from the umbilicus) lie in a more horizontal plane than the ﬁgures appear to indicate. Normally, the testes and the descending colon are in contact with, and completely concealed in front by, small intestine. But the posterior abdominal wall has been straightened by traction exerted upon it through the hook, and they are thus rendered visible.
It is stated in Poirier’s Anatomy that the root of the mesentery upon the fourth portion of the duodenum is something new, the result of a process of adhesion of the peritoneum of the intestinal loop to the meso-duodenum between the superior mesenteric artery and the duodeno—jejunal ﬂexure.
But all the evidence I have is in favour of this part of the root of the mesentery being simply the intestinal border of the mesentery of the small intestine. It has always been present.
Fm. 8.—Dia.gram to illustrate the arrangement of the peritoneum in a. 37-mm. foetus. The ciecum is supposed to have been pulled from the umbilical oriﬁce (in which it lay) towards the right. The posterior (direct) layer of the great omentum has been cut at its junction with the anterior (reﬂected) layer. The mesentery of the intestinal loop has fused to the mesoduodenum where this covers the head of the pancreas, and the “secondary root-area. "is thus formed. The anterior and posterior surfaces of the duodenum are still free; and the retropancreatico-duodenal space contains part of the liver. The roots of the meso-gastrium and meso-duodenum, and the root of the mesentery of the intestinal loop (secondary root-area) and that of the terminal intestine, are still practically in the middle line
This view of the origin of the fourth portion of the duodenum is further supported by the fact that the fossae which may lie behind this part never extend behind the head of the pancreas.
The root of the mesentery is completed by the fusion, to the parietal peritoneum and to the duodenum, of the colic portion of the mesentery of 500 Mr Douglas G. Reid
the intestinal loop, downwards to the line of the ileo—colic vessels (see ﬁgs. 1, 4, 5, 9, 10).
A blood-vessel lying in a sheet of peritoneum forms a relatively rigid bar about which, as an axis, one part of the sheet may rotate towards another part.
I have already shown that such a plication may determine the position of the arteries along the root of the pelvic mesocolon (see my “Studies,” Part II.).
In the same way, such a plication will determine the position of the ileo—colic vessels along the root of the mesentery, since the more passive colic part of the mesentery of the intestinal loop can, as a rule, solder to the posterior peritoneum downwards to the line of these vessels, about which the small intestinal part of the mesentery of the intestinal loop has rotated forwards, but no farther. The development of the genito-mesenteric fold, however, may cause a displacement of the root of the mesentery from this line (see my “Studies,” Part I.).
The intermediate retro-duodenal fossa would appear to result from the soldering down of the bowel which forms the fourth portion of the duodenum occurring ﬁrst along the left aspect of the head "of the pancreas and the superior mesenteric artery, and in the region Where the inferior mesenteric vein may come into relation with the superior duodenal fold. If the adhesion extend towards the left, the fossa will become shallower, and may ﬁnally be obliterated.
The part of the bowel which is most ﬁxed through its relations to other relatively immovable parts is the part which ﬁrst tends to solder down.‘
The Relations or the Peritoneum or the Intestinal Loop to the Duodenum
The colon usually lies parallel to the ﬁrst portion of the duodenum. It lies along the lower border, or upon the anterior surface of this part (see ﬁgs. 5, 9).
In five out of twenty foetuses (20 per cent. of cases) it forms a small loop (the right colic loop of J onnesco) as it lies opposite the duodenum.
There are two chief arrangements (see ﬁg. 9).
(1) The peritoneum of the intestinal loop becomes adherent to the whole of the permanently anterior lamina of the meso-duodenum up to the lower border of the ﬁrst part of the duodenum. At this level it bends downWards upon itself, so that the previously posterior surface of the colon becomes anterior, and a short transverse mesocolon persists which may subsequently disappear as the result of fusion (see ﬁg. 9, A). This is the condition which is already present in my 37-mm. foetus (see fig. 8). The meso—gastrium and the transverse mesocolon are still quite free from one another, but almost meet at the level of the lower border of the ﬁrst part of the duodenum. The lower part of the root of the meso-gastrium and the upper limit of the secondary root-area lie close together (closer than could well be indicated in the ﬁgure).
- 1 Jamming of viscera between relatively immovable parts may help to determine adhesion. Thus in four out of thirteen specimens the left extremity of the transverse colon is jammed between the ancreas and the spleen, and adheres, as in the adult, to the inferior surface of the body 0 the pancreas. In the other nine cases, althou h the colon is in contact with the body of the pancreas, there is no such jamming, an a ﬁssure, the walls of which are lined by the meso-gastrium, intervenes between the colon and the pancreas.
FIG. 9.—Diagram to show the arrangement of the peritoneum opposite the duodenum. The angle marked + may disappear through fusion. In the left root-fold are lodged the ileo-colic artery and vein, nerve ﬁlaments, and a number of lymphatic nodes. This fold is described in Part II. of my “ Studies.”
(2) There is the same disposition without the persistence of a mesocolon (see fig. 9, B).
It has been noted in Part III. of my “Studies” that, after an arrangement has been acquired as described under (1), a secondary movement may occur of the transverse colon towards the left and headwards.
The colon and peritoneum of the intestinal loop always completely cover the meso-duodenum below and to the right of the pylorus.
In the 25—mm. embryo the meso-gastrium is free exactly to the extent indicated in ﬁg. 8 for the 37-mm. foetus, but has not begun to project downwards beyond the stomach as in that foetus. Later it will fuse with the transverse mesocolon and colon, and still later the right omental process appears. When this develops, it extends, therefore, over the peritoneum of the intestinal loop, and not overvthe meso-duodenum such as is ﬁgured and described in the classics (see also ﬁg. 10).
Fig. 10. 10.-—Foetus 127 cm. long. The peritoneum between the duodenum and the transverse colon belongs to the mesentery of the intestinal loop, and is not meso-duodenum. Therefore in this foetus had the right omental process developed later, it would have extended over peritoneum of the intestinal loop, not over meso-duodenum such as is ﬁgured and described in the classics (e.g. Poirier’s Anatomy). In all the other fcetuses the mesu-duodenum to the right of and below the pylorus is completely covered by the transverse colon and the mesentery of the intestinal loop (see fig. 9). The ﬁgures and descriptions given in the books dealing with the development of the peritoneum are inaccurate in this respect. The terminal intestine forms a loop which lies in the right iliac fossa.
The Special Relations of the Duodenum
(1) The caudate lobe (process) of the liver may lie directly behind the ﬁrst and second portions of the duodenum, as has already been described. (2) The right suprarenal body may descend behind the duodenum to a marked extent (see ﬁg. 5) ; and even when the caudate lobe lay in front of it to ‘the extent shown in ﬁg. 5, it came into direct relation, below the liver, with the lower end of the second portion of the duodenum. When there is no marked recess it also comes into direct relation with the duodenum at the angle between its ﬁrst and second parts. Indeed, it often descends behind the second portion to_the upper part of the junction of this with the third portion.
In the full-time foetus mentioned it lay behind the upper half of the second part of the duodenum. It may also come into _contact with the head of the pancreas (of. ﬁg. 5) to the right side of the inferior vena cava. The left suprarenal body is an immediate relation of the duodenum at the duodeno-jejunal ﬂexure.
(3) The genito-mesenteric fold gains an attachment to the duodenum (see ﬁg. 1). The suspensory muscle of Treitz} “as Professor Cleland is in the habit of pointing out in his lectures, seems to have more importance than is usually attributed to it. . . . The duodenum may curve downwards even as far as the right iliac fossa,2 and yet its junction with the jejunum is always on the left side of the superior mesenteric artery, beneath the transverse mesocolon, owing to the suspension of this part of the small intestine by the musculus suspensorius duodeni.” This muscle undoubtedly tends to become hypertrophied when the duodenum is unusually free (see my paper “Imperfect Torsion of the Intestinal Loop,” Journal of Anatomy and Physiology, vol. xlii.).
But I have pointed out another probable cause of downward displacement of the duodenum. This is the traction which may apparently be exerted upon the duodenum at the junction of its second and third parts by the genito-mesenteric fold.
In an adult the duodenum, at this junction, descended to the level of the disc between the last lumbar and ﬁrst sacral vertebrae (see ﬁg. 3). This was most probably due to the unusually large cirrhotic liver.
Nevertheless, the genito-mesenteric fold should be kept in mind as another probable cause of some degree of downward displacement of the duodenum (see also footnote, ﬁg. 1).
(4) The left root-fold lies in the foetus in front of the fourth portion of the duodenum, along the line of the root of the mesentery passing outwards towards the caecum (see ﬁgs. 4-, 5, 9, 10).
- 1 A good ﬁgure of this muscle is given in Spalteholz’s Atlas (fig. 633). 2 It is interesting to note all the abnormal contents of this fossa—duodenum, trans verse colon, pelvic colon, liver, lower extremity of right kidney, testis of adult, etc. See also ﬁg. 10. 504 Mr Douglas G. Reid
(5) The pelvic colon may ascend to the duodenum, and may also be distinctly overlapped by the left root—fold.1
The Genesis of Certain Folds of Peritoneum in Relation to the Duodenum
I have already shown (“ Studies,” Part III.) that if the “bloodless” fold of Treves adhere to the abdominal wall, it may become enormous through stretching during the descent of the caecum. I have also shown that folds may be present at the periphery of “the superior area of gastric adhesion” (“bare area”). A distinct fold may also be seen sometimes at the lower limit of the adhesions which bind the ascending colon to the parietal peritoneum.
In ﬁg. 4 a fold is illustrated which lies at a bend of the bowel, and at the lower limit of the adhesions ﬁxing down a part of the jejunum. It is very similar in appearance to the inferior duodenal fold which is present, as is also the superior, in a number of my 12 to 22-cm. foetuses.
Folds (see ﬁgs. 2, 3) may also be seen at the duodeno—_jejunal ﬂexure connecting the bowel at this point with the transverse mesocolon.
At these points the connective elements of two originally distinct peritoneal sheets have, of course, become continuous with one another.
Just as in the case of the “ bloodless” fold, traction upon these connective elements, where they are continuous, will naturally tend to elongate them into a fold, provided the area of adhesion be not too diffuse. This will tend to occur most where stress is greatest, eg. at the duodeno-jejunal ﬂexure.
At this ﬂexure there is not only the traction exerted directly upon the adhering connective elements by the jejunum itself, but the stomach presses downwards upon the bowel, and the upper horizontal coils of small intestine press upon it from left to right. Stress also concentrates itself upon the duodenum at the angle between its third and fourth portions. Here there is the pressure exerted upon it from left to right by the upper horizontal coils, and from below by the vertical coils of small intestine.
Through traction upon the connective element of the outer coat» of the bowel some muscle ﬁbres of the gut may also be drawn, as it were, into a peritoneal fold (see my paper on “The Caeco—appendicular Fold,” Journal of Anatomy and Physiology, vol. xlvi.).
- 1 Should adhesions develop between the upper part of an omega loop of pelvic colon and the third part of the duodenum and adjoining mesentery and parietal peritoneum, the pelvic colon may remain permanently ﬁxed in the abdominal cavity. I have recently seen this condition, due to strong adhesions, in two adult bodies otherwise normal as regards peritoneal adhesions. Apart from the question of this impairing the functional activity of the bowel, it is possible that in such cases diﬁculties might arise in an attempt to pull downwards the right limb of the omega loop in the operation of excision of the rectum by the sacral route where the growth is found to extend far upwards.
Traction or pressure exerted upon peritoneum on each side of a bloodvessel may also, in some "cases, produce a vascular fold. I have described such a fold in connection with the genito—mesenteric fold (“ Studies,” Part I., Journal of Anatomy and Physiology, vol. xlv.).
This idea is further illustrated in an 18—c1n. foetus. Here the upper part of the inferior mesenteric vein, taking its usual arched course, lay, above a point indicated by + in ﬁg. 2, along the free margin of a fold of peritoneum which formed the anterior wall of a fossa 2'5 mm. deep. The left border of the fourth portion of the duodenum, up to the duodenojejunal ﬂexure, was lodged in this fossa, but did not adhere to the fold. Had the duodenum adhered to the upper half of the fold, quite a typical superior duodenal fold, containing’ the inferior mesenteric Vein, and fossa would have been formed. V
Thus, if, as in this case, the fourth part of the duodenum, being practically ﬁxed below, whilst at the duodeno—_jejunal ﬂexure it is in contact with the pancreas and adheres to some extent to the transverse mesocolon, remain free behind, it may, during growth, ﬁnd space for itself by burrowing its way, as it were, under the vein.
These views, of course, do not imply that endothelium is dragged off some other part in order to coat the fold which is produced. In some cases such a fold may disappear later through fusion with adjacent peritoneum.
The cystocolic ligament is present in 30 per cent. of foetuses. I have included in this some cases in which the colon adheres directly to the body of the gall-bladder. In the two cases I have mentioned_in which there is a well-marked retro-pancreatico-duodenal recess the colon and duodenum, adhering together, are propped forwards, as it Were, by the caudate-lobe of the liver lying in this recess (see ﬁg. 5); and both adhere directly to the body of the gall-bladder at the angle between the ﬁrst and second parts of the duodenum. The endothelial surfaces, thus brought together, are directly continuous with those of the lesser omentum.
Thus we have the birth of What obviously could become later a deﬁnite cystocolic fold continuous with the lesser omentum, and passing over the duodenum, to the colon. I have indicated in Part III. of my “Studies” that a direct adhesion of the colon to the lesser omentum may sometimes also give rise to this ligament.
Peritoneal bands consequent upon inﬂammation may also, of course, arise through direct adhesions and subsequent elongation the result of traction.
The Subdivision of the Abdominal Cavity by Peritoneal Folds and Adhesions
A. Subdivisions of the Greater Sac of Peritoneum
(1) In two adult bodies dissected at Cambridge, Lent Term, 1913, I found the great omentuin adhering to the anterior abdominal wall along an uninterrupted line from a point a little to the right of the middle line outwards to the right abdominal wall (see ﬁg. 11). Thus a compartment was formed between the transverse colon and great omentum below and the visceral surface of the liver above.
Fig. 11. This figure, constructed from three specimens (two adults and a foetus) examined by me in the Cambridge dissecting-room, Lent Term, 1913, illustrates the subdivision, more or less complete, of the abdominal cavity by peritoneal folds and adhesions. A and B indicate the two compartments of the lesser sac (represented by an interrupted line) resulting from the continuity of the superior and inferior areas of gastric adhesion. D and 0 indicate the compartments formed through an adhesion, in both adults, of the great omentum to the anterior and right abdominal walls. E and F are the compartments, below the mesentery, to the right and left of the genito-mesenteric fold. The pelvic colon (the M-shaped form was resent. well marked, in one of the adults) occupies compartment F; the caecum and appen ix, and part of the ileum, occupy compartment E. S indicates the compartment for the spleen. It is closed in front and below by the splenic process of peritoneum. M and N are the compartments on each side of the falciform ligament.
Inﬂammatory effusions from the stomach, liver, or gall-bladder would‘ readily have collected in it; and it would have formed an important barrier in restricting their spread into the general peritoneal cavity. It formed, as it were, a ready-made abscess cavity (see ﬁg. 11, D) shutting off the right portion of the recess, between the liver and the transverse colon and mesocolon, to which the name of the hepato—c0lic recess may be given.
(2) The pre-splenic fold of the splenic process of peritoneum is present normally in the adult. The sub-splenic part of this process is also sometimes seen as a distinct fold in the adult.‘ When fully developed it adheres to the diaphragm; and in several adults I have noted that, as the presplenic fold lies between the spleen and the diaphragm, it adhered to the diaphragm, as well as to the diaphragmatic surface of the spleen. Thus the spleen comes to lie in a deﬁnite compartment,closed in front and below by the splenic process. This compartment may be termed the splenic compartment or recess (see ﬁg. 11, S).
(3) The space beneath the transverse colon and mesocolon to the left of the duodeno-jejunal ﬂexure, and below the root of the mesentery, may be termed the sub-mesenteric recess. The genito-mesenteric fold, when present, divides this into right and left sub-mesenteric recesses (see ﬁg. 11, E, F).
The caecum2 and appendix lie in the right recess; the pelvic colon lies in the left.
In some cases, as in one which I record in another paper, it would appear to be best to cut through the left (genito-mesenteric) wall (to which the appendix and meso—appendix adhere) of the right sub-mesenteric recess in order to reach the appendix. If this can be done, considerable tearing and rough usage of the peritoneum by the surgeon would be avoided. The small intestine should ﬁrst be pulled forwards. The genito—mesenteric fold isthus exposed.
- 1 Since describing it I have seen the sub-splenic fold, distinct and well marked, in two adults. In both it adhered to the diaphragm and formed the suspensory ligament of the spleen. In one it co-existed with the phreno-colic-ligament of Tol t ; in the other, Toldt’s ligament had not developed.
- 2 It is, of course, important to remember that, in the adult, the caocum may he found lying in the central region of the abdomen at any point between the umbilicus (at which it lies in my 37-mm. foetus) and pelvic cavity, into which it may also descend.
In the right lateral region I found the caccum of an adult wedged between the liver and the diaphragm. Engel has noted a similar case. In this region it may also lie at any level below the liver In my 12- to 22-cm. fwtuses it lies in front of the right kidney, or immediately below it. In this latter situation the appendix is usually in a retro-colic plane, and, as a rule, after ascending to the kidney is bent downwards and thus accommodates itself to the space available between the kidney and the parietal peritoneum below this prominent organ.
If the lower part of the ascending colon be free, the caccum may be pushed upwards by coils of small intestine, but yet could be pulled downwards by the surgeon (see my paper in the Journal of Anatomy and Physiology, vol. xlvi. p. 239).
The ceccum has also been found lying in the left iliac fossa. “Remarquons—que le czecum peut faire partie de toute les hernies ombilicale, crurale, inguinale, et meme du cote gauche.”
(4) Above the root of the mesentery, and below the transverse colon and mesocolon, is the supra-mesenteric recess or compartment (see ﬁg. 11, O).
(5) The right and left suhdiaphragmatic recesses are placed between the liver and the diaphragm on each side of the falciform ligament (see fig. 11, M, N).1 _,
B. Subdivisions of the Lesser Sac of Peritonenm
I have already shown that, through the continuity of the superior with the inferior area of gastric adhesion, the lesser sac of peritoneum may be subdivided into two compartments—(a) the hepatic or minor compartment (see fig. 11, A), and (b) the major compartment (see ﬁg. 11, B).
In the papers I have now published on the intestine and peritoneum new names have been introduced into anatomy ; and I have named the parts only after a careful study of their relations (primitive and ultimate). At the same time, I have kept in mind any importance that these parts might have, or acquire, especially from a surgical or gynaecological point of view. I have avoided, as far as possible, altering any name given to a part by its original discoverer. But in some cases this was really necessary as the descriptions given were most inadequate. In some cases one had to add another name to an old one. Thus there are two areas of gastric adhesion, not simply one area which is “ bare” as regards its peritoneum. There are also two root-folds.
The following is a list of some of the names I have introduced :—
1. The Genito-mesenteric Fold.
2. The Root-folds and Root-fossae.
- (a) The Left or Superior Root-fold and Root-fossae.
- (b) The Right or Inferior Root-fold (Mesenterico-caecal Fold of Jonnesco) and Root-fossa.
3. The Caeco-appendicular Fold.
4. The Pelvic (Jonnesco) or Ilio-pelvic Colon.
- (a) The M-shaped Form.
- (b) The Compressed Omega Form.
- (c) The Compressed and Incompletely Inverted Omega Form. (There is also (cl) an Omega (Treves) Form.)
5. The Splenic Process of Peritoneum.
- (a) The Pre-splenic Part or Fold.
- (b) The Sub—splenic Part or Fold.
6. The Areas of Gastric Adhesion.
- (a) The Superior Area of Gastric Adhesion (“bare area”)
- (b) The Inferior Area of Gastric Adhesion.
7. The Supra-adhesion Foramen. (The Spigelian Uncus (described in my “ Studies,” Part IV.) when present abuts against this foramen.)
- (a) The Retro - pancreatico - duodenal Fossa.
- (b) The Superior Retro-duodenal Fossa.
- (c) The Intermediate, Middle, or Lateral Retro-duodenal Fossa.
- (d) The Inferior Retro-duodenal F ossa (Retro-duodenal Fossa of J onnesco).
8. The Retro-duodenal Fossae.
9. The Retro-pancreatico-duodenal Recess.
- 1 In operating for perforated astric ulcer “ the sub-diaphragmatic spaces are. especially liable to be overlooked ” (Treves, anual of Operative Surgery). “ Special attention should be directed to the space between the diaphragm and the liver on each side of the sus ensory li ament, (and) the space between the stomach and the spleen ” (Alexis Thomson an Miles, Manual of Surgery).
|Historic Disclaimer - information about historic embryology pages|
|Embryology History | Historic Embryology Papers)|
Cite this page: Hill, M.A. (2020, July 3) Embryology Paper - Studies of the intestine and peritoneum in the human foetus - part 6. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Studies_of_the_intestine_and_peritoneum_in_the_human_foetus_-_part_6
- © Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G