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as follows :-It forms the inferior boundary of the foramen epiploicum, and,

it is in relation to the caudate process of the liver, while the quadrate lobe lownwards over it and to the right. The hepatic artery is in contact for a

the superior border. Below, it rests on the head and neck of the pancreas. castro-duodenal artery, and the bile-duct lie in contact with it on the left

Aorta

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Fossa for caudate lobe Right Inferior phrenic vessels

Inferior Vena cava

Hepatic vein Hepatic artery Portal vein

Pylorus e-duct nd

ac ein

iac ery iliac vein

Fig. 932.—THE VISCERA AND VESSELS ON THE POSTERIOR ABDOMINAL WALL. liver, and most of the intestines have been removed. The peritoneum has been preserved on the idney, and the fossa for the caudate lobe. When the liver was taken out, the vena cava was left . The stomach bed is well shown. (From a body hardened by injection of chromic acid. )

hind them the duodenum comes into contact with the right aspect of the inferior The superior pancreatico-duodenal and the right gastro-epiploic vessels pass forwards ferior margin. oneal relations are similar to those of the pyloric end of the stomach for about an

therefore at first invested by peritoneum on the right and left aspects, and the passes upwards from its superior border as the right portion of the lesser omentum, e hepato-duodenal ligament, while from its inferior border the descending folds of the

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all of the the pancres Tean orifice

peritoneum pass downwards. The peritoneum is reflected from off the left surface on to the pancreas and abdominal wall, and forms a fold known as the right gastro-pancreatic fold, while the peritoneal covering of the right side is continued onwards along the whole of this part of the duodenum.

Pars Descendens.— The descending part (O.T. second portion) begins at the neck of the gall-bladder, passes down behind the transverse colon, and ends at the right side of the third or fourth lumbar vertebra. In length it measures 3} or 4 inches (807 to 10 cm.).

Its relations are as follows :—It lies on the right of the vertebral column and the inferior vena cava, from the first to the third or fourth lumbar vertebra, and is anterior to the pelvis

Top of omental bursa
Inferior vena cava

Left triangular ligament of liver
Lesser omentum (cut)

Esophageal opening in diaphragm

Gastro-phrenic ligament Right triangular

Corresponds to uncovered area of stomach ligament of liver

Gastro-splenic ligament (eut)

Pars Infer

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Phrenico-colic ligament
Transverse colon crossing duodenum
Head of pancreas

Left end of transverse mesocolon
Gastro-colic ligament (cut)

Left colic flexure
Transverse mesocolon (cut)

Root of mesentery (cut)
FIG. 933.—THE PERITONEAL RELATIONS OF THE DUODENUM, PANCREAS, SPLEEN, KIDNEYS, ETC.
From a body hardened by injections of formalin. When the liver, stomach and intestines were removed the

lines of the peritoneal reflections were carefully preserved. The peritoneum is coloured blue.
of the right kidney, the right renal vessels, and ureter, and also, to a varying extent, the front of
the right kidney itself; while, below the level of those structures, it rests upon the psoas majar
muscle.

The lateral aspect is in contact with the sloping inferior surfaces of the liver in its superior part, and with the right flexure of the colon below.

Peritoneal Relations. The anterior aspect is covered by peritoneum, except about its middle, where the root of the transverse mesocolon crosses the duodenum. Not infrequently, the transverse colon has no mesentery, but is itself in direct contact with the wall of the duodenum. In other cases, the colon is in contact with the peritoneal surface of the duodenum, below the line of reflection of the transverse mesocolon.

The head of the pancreas is in contact with its concave left margin, and occasionally overlaps it anteriorly and posteriorly; and along the margin of the pancreas, both anteriorly and poe. teriorly, are branches of the superior and inferior pancreatico-duodenal vessels, the veins often forming a dense network on the posterior aspect.

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er passing down behind the superior part of the duodenum, descends between reas and the descending part, nearly as far as its middle ; there it is joined ct, and the two, piercing the wall of the duodenum obliquely, open by a

inner aspect, about 3 to 4 inches (8-7 to 10 cm.) beyond the pylorus. -The inferior part (O.T. third portion) begins at the right side of a lumbar vertebra. It is described in two parts, pars horizontalis, ction, and pars ascendens; and it shows that arrangement in

talis runs more or less transversely to the left across the inferior vena cava two inches, and the pars ascendens passes very obliquely, or even vertically, the aorta and left psoas major muscle. Finally, having reached the inferior eas, it bends forwards, and passes into the jejunum. crossed (about the junction of its two divisions) by the superior mesenteric

the root of the mesentery (Fig. 933). On each side of this it is covered by ine. Posteriorly, the pars horizontalis lies across the vena cava inferior; the pars ne aorta, the left renal vein and occasionally also the artery, and the left psoas f which separate it from the vertebral column. Above, it is closely applied in o the head of the pancreas. The left side of the pars ascendens, which is free, h some coils of the small intestine. ations. The inferior part of the duodenum is covered by peritoneum on its nroughout, except where it is crossed by the superior mesenteric vessels and the tery, which contains these vessels (Fig. 933). * In addition, its ascending part

this membrane on its left side. nt of the root of the mesentery begins, above, quite close to the duodeno-jejunal front of the duodenum ; thence it runs down on the anterior aspect of the nd finally leaves the duodenum about the union of the two divisions of its third

| Fossæ. In the neighbourhood of the pars ascendens are found three ssæ of the peritoneum which are of some surgical interest ; they are nferior duodenal and the paraduodenal fossa (Fig. 934). Other rarer forms y present.

ascending part of the duodenum is drawn over to the right, and the n its left side and the posterior abdominal wall is examined, one or two Ids of peritoneum

Transverse meso. y be found cross- Transverse colon at angle from the to the abdominal fold has one edge

the duodenum, the parietal peri

the left of the whilst the third is bounds the opening 1 pouch which lies me fold, the recessus Duodenum jejunalis. Of these

Superior upper is termed the

duodenal fossa deno-jejunalis, and it

Inferior ed near the termina-V duodenal fossa The mesentery (cnt).

Inferior mesenteric vein he duodenum, with its

Left colic artery rected up and its free down. It sometimes

FIG. 934.—THE DUODENAL FOSSÆ AND FOLDS. s between its two layers The transverse colon and mesocolon have been thrown up, and the mination of the inferior mesentery has been turned to the right and cut. The paraduodenal eric vein. Behind it

fossa (of Landzert) is situated to the medial side of the inferior

mesenteric vein, between it and the terminal part of the duodenum. prolongation from the

It is not shown in the illustration. sus duodeno-jejunalis 1 the superior duodenal fossa. Its opening looks downwards, and will usually

the tip of a finger (Fig. 934). The second, known as the plica duodeno-mesocolica, ced lower down, at the side of the same part of the duodenum. Its free border is med upwards, as is the mouth of the inferior duodenal fossa, which lies behind it. latter is larger and more constant than the superior duodenal fossa, and is present

per cent. of bodies, whilst the superior is present in 50 per cent. (Jonnesco). Paraduodenal Fossa (fossa of Landzert). — This fossa, which is seen best in the

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infant, is placed some distance to the left of the ascending part of the duodenum. It is
produced by the inferior mesenteric vein raising up a fold of peritoneum, as it runs
medially along the side of the fossa, and then above it (see Fig. 934, where the vein, but
not the fossa, is shown). It is limited below by a special fold (the mesenterico-meso-

colic fold). According to Moynihan, this is the
only fossa to the left of the duodenum capable
of developing into the sac of a hernia ; and
when this occurs, the inferior mesenteric vein

always lies in the anterior margin of the orifice
plica circularis
Duodenal

of the sac (accompanied for some distance by
papilla the ascending branch of the left colic artery).
-Common open-
ing of bile and Peritoneal Relations of the Duodenum.-Whilst
pancreatic duct
Plica longitudi.

the relations of the peritoneum to the second and
nalis duodeni third portions of the duodenum are usually described

as in the foregoing account, it should perhaps be
pointed out, that it is not really the front, but the
right half of the circumference of the descending
portion which has a serous coat. Similarly, it is

the inferior and anterior half of the circumference Fig. 935.—THE PAPILLA DUODENI IN THE of the horizontal portion of the inferior part which INTERIOR OF THE DUODENUM.

is clothed by peritoneum, whilst considerably more

than half of the circumference of its ascending portion is covered; for the peritoneum forms a fold running in behind this portion, in additica to covering its left side and half its anterior aspect.

Interior of Duodenum.—No plicæ circulares are found in the duodenum for an inch or two beyond the pylorus. They then begin; at first as low, scattered, and irregular folds ; further down, they gradually become larger, more regular and more numerous; and by the time the middle of the descending part is reached they have attained a considerable development. In the inferior part of the duodenum the folds are large, prominent, and closely set.

On the inner aspect of the descending portion, about its middle-namely, 31 or 4 inches (87 to 10 cm.) beyond the pylorus—is seen a prominent papilla, on which the bile and pancreatic ducts open by a common orifice (Fig. 935). This is known as the papilla duodeni (Santorini).

The papilla duodeni is placed beneath, and protected by, a prominent, hood-like plica cireularis, which is situated immediately above it. From its lower margin a firm ridge of the mucous membrane, the plica longitudinalis duodeni, descends for a considerable distance, and acts as a frenum, which fixes the papilla and directs its apex somewhat downwards (Fig. 935) The papilla is prominent, and nipple or dome-shaped, and at its summit is placed the small orifice, which will usually admit the point of a pencil; the whole bears a close resemblance to the nozzle of a perfume-spray.

Nearly an inch higher up, and invariably on the ventral side of the papilla (sometimes as much as a } to 1 inch distant), is seen a second and smaller papilla, the caruncula minor of Santorini, at the point of which is placed the very small orifice of the accessory pancreatie duct. This second papilla seems to be constantly present, although sometimes so small that it may easily escape detection unless carefully sought for. When well developed, it may have a hood-like plica circularis and a little frenulum, like those of the bile papilla.

Structure of the Duodenum.—The tunica serosa, which is incomplete, has already been described in detail, in connexion with each part of the duodenum.

The tunica muscularis is well developed, and is pierced by the bile and pancreatie ducts, but otherwise calls for no special description.

The tela submucosa differs from that of the rest of the small intestine, in that it contains, especially in the superior half of the duodenum, the glandulæ duodenales [Brunneri). These are small acino-tubular glands, closely resembling the pyloric glands of the stomach ; they lie in the submucous coat, and send their ducts through the muscularis mucose to open on the surface between the glandulæ intestinales, or sometimes into these glands themselves (Fig. 929). They can be exposed by the removal of the peritoneal and muscular coats, and also some of the submucosa, when they appear as little round or flattened masses of a reddish-gray colour, varying in size from oth to 19th of an inch in diameter (-5 to 2:0 mm.). They form an almost continuous layer as far as the opening of the bile duct; beyond this they diminish progressively, and completely disappear near the duodeno-jejunal Rexure.

The tunica mucosa, which is thicker in the duodenum than in any other part of the small intestine, is covered throughout with broad, short villi.

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Various Forms of Duodenum.—Three different types of duodenum have been described — The annular, in which the curves separating the various parts are open, and the two remities come fairly close to one another. (2) The U-shaped, in which the horizontal part of

inferior part is very long, and the ascending part is nearly vertical; and (3) the V-shaped odenum, in which the horizontal portion of the inferior part is very short or absent. Vessels and Nerves.—The duodenum receives its blood from the superior and inferior creatico-duodenal arteries, branches of the gastro-duodenal and superior mesenteric arteries pectively. The blood is returned by the corresponding veins, the superior of which opens into superior mesenteric, and the inferior into the beginning of the portal vein. The lymph vessels of the duodenum follow for the most part the course of the blood-vessels. From the anterior surface, lymph vessels pass along the course of the inferior pancreaticowenal artery, and communicate with lymph glands found along the course of that vessel. ence they pass to the inferior cæliac glands, beside the origin of the superior mesenteric artery. The vessels from the posterior aspect accompany the superior pancreatico-duodenal artery, imunicate with the inferior gastric glands, and terminate in the cæliac glands. The nerves come from the cæliac plexus of the sympathetic. Flexura Duodenojejunalis. — When the ascending part of the duodenum ches the inferior surface of the pancreas, at a point opposite the left side of

first or second lumbar vertebra, it turns abruptly forwards, downwards, and the left, and passes into the jejunum. This abrupt bend is known as the deno-jejunal flexure. Unlike the rest of the duodenum, which is subject to siderable variations in position in different individuals, the duodeno-jejunal ure is fixed by a thin band of unstriped muscle, which is attached above to the ong connective tissue around the coeliac artery, as well as to the left crus of the phragm. This band passes posterior to the pancreas, and inferiorly it joins the scular coat of the duodenum at the flexure. It is known as the m. suspensorius deni (O.T. muscle of Treitz). The duodeno-jejunal flexure is occasionally directed to the right, and it lies at ariable distance from the root of the transverse mesocolon. When the attachat of the transverse mesocolon is low, the duodeno-jejunal flexure is in contact h it.

Duodenal Pouches or Diverticula. - Occasional diverticula are found passing from the denal wall in different directions. Such diverticula may be hernial protrusions of the ous and submucous coats through the muscular wall, termed false diverticula, or they may true” diverticula, in which all the coats are represented. Chey are usually situated on the aspect of the duodenum which is in contact with the pancreas, frequently in the neighbourhood of the orifice of the bile duct. Some of these appear to be due to the pressure from the interior of the duodenum, while rs, and the majority of the true diverticula, are rather congenital in origin, and are ibly associated with the diverticula which give rise to the liver and pancreas.

HEPAR.

The liver is the large glandular organ which secretes the fluid called bile ). It occupies the superior and mainly, the right portion of the abdominal cavity,

lies immediately below the diaphragm. Its secretion is conveyed away from it by the hepatic ducts and the bile-duct to duodenum. With the bile duct there is connected a pear-shaped diverticulum, gall-bladder (vesica fellea), which lies in contact with the liver, and which es apparently for the temporary storage of bile. In addition to secreting bile, the liver plays an important part in the abolism of both the carbohydrate and nitrogenous materials absorbed from the stine which are conveyed to it by the portal vein, and it also has to do with production and the destruction of some of the blood-cells. Physical Characters. The liver is a large irregularly shaped mass, of & lish-brown colour, soft and pliant to the touch, somewhat readily lacerated, and nly vascular. It is of uniform consistence throughout, and little of its internal structure can nade out by naked-eye examination. If, however, a torn surface is examined, liver tissue is seen to be somewhat granular. Under the investing peritoneum surface is somewhat mottled. This mottled or granular appearance is due to the lobules (lobuli hepatis) of

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