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apex of the bladder below, where it usually becomes much stouter. Lateral to the urachus, and some distance from it (Fig. 965), will be found, in the same fatty tissue, (b) two stouter fibrous cords, the obliterated umbilical arteries (O.T. obliterated hypogastric arteries), forming the plica umbilicalis lateralis dextra and sinistra. Traced upwards, these also become more slender, and approach the urachus, along with which they are connected to the umbilicus. Below, Lesser omentum.. they grow thicker, and can be followed backwards along the side wall of the pelvis to the hypogastric arteries, which they join. (c) More laterally still, the inferior epigastric arteries are seen running upwards and medially from the external iliac trunk on each side.

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When the anterior abdominal wall is examined from behind, it will be seen that these five structures, which lie on the front of the peritoneum, carry that membrane inwards towards the abdominal cavity in the form of five more or less distinct ridges, known as the plica umbilicalis media, plicæ umbilicales laterales, and plicæ

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epigastrica, respectively. In FIG. 964.-DIAGRAMMATIC MEDIAN SECTION OF

relation to these are found on each side three peritoneal fossæ, known as the foveæ inguinales (O.T. inguinal pouches or fossæ).

Epiploic foramen

Pancreas

Duodenum, transverse part Transverse colon

FEMALE BODY, to

show the peritoneum on vertical tracing. The great sac of the peritoneum is blue and is represented as being much larger than in nature; the bursa omentalis is coloured red; the peritoneum in section is shown as a white line: and a white arrow is passed through the epiploic foramen from the great sac into the bursa omentalis.

The fovea inguinalis lateralis lies lateral to the inferior epigastric artery, and corresponds to the position of the abdominal inguinal ring. At its bottom is often found a dimple-like depression of the peritoneum, indicating the point from which the processus vaginalis passed down, in connexion with the descent of the testis. The fovea inguinalis medialis is situated between the inferior epigastric and the obliterated umbilical arteries; whilst the fovea supravesicalis lies to the medial side of the obliterated umbilical artery, namely, between it and the urachus.

Between the inferior epigastric artery laterally, the margin of the rectus abdominis muscle medially, and the inguinal ligament below, there is a small triangular region, called Hesselbach's triangle. The obliterated umbilical artery, in passing upwards, crosses this triangle, dividing it into a lateral and a medial part. The middle inguinal fossa corresponds to the lateral division of the triangle, and the medial fossa to its medial division.

Still another fossa of the peritoneum is seen in this region, just beneath the medial part of the inguinal ligament, corresponding to the position of the femoral ring, and consequently known as the fovea femoralis. It may be added that the ductus deferens crosses the lateral part of the fovea femoralis, and the obliterated umbilical artery its medial part. The significance of those fossæ is referred to in connexion with the applied anatomy of the inguinal and femoral regions.

Near the median plane, above the umbilicus, the peritoneum is carried back from the anterior abdominal wall and diaphragm to the parietal surface of the liver in the form of a crescentic fold, the falciform ligament of the liver (described with the liver), which connects the liver to the abdominal wall. This fold lies somewhat to the right of the median plane, and extends almost as low down as the umbilicus.

It consists of two layers of peritoneum, between which, in the lower border of t fold, runs the round ligament of the liver-the remains of the left umbilical ve of the foetus.

Posterior Wall of the General Peritoneal Cavity. The peritoneum clothing ti anterior abdominal wall is continued on to the inferior surface of the diaphrag Thence it is reflected on to the superior surface of the liver, and there the anteri wall of the great sac becomes continuous with the posterior wall. The peritoneu on the posterior wall first clothes the superior surface of the liver, then turns roul its anterior border, and is continued back on the inferior surface as far as the attach ment of the lesser omentum, where it quits the liver and passes down, as tim anterior layer of the lesser omentum, to the stomach and the duodenum.

The line of reflection of the peritoneum from diaphragm to liver is interrupted near the medi plane by the falciform ligament. The portion lying to the right of this fold forms the super layer of the coronary ligament; that to the left of it, the superior layer of the left triangula ligament of the liver.

The extent to which the peritoneum passes uninterruptedly back on the inferior surface of the liver varies according as it is traced at the right, the left, or the middle portion of the liver. clothes the right portion as far back as the inferior edge of the uncovered area of the liver, whet it is reflected on to the posterior wall of the abdomen and the superior extremity of the righ kidney (constituting the hepato-renal ligament), as the inferior layer of the coronary ligament On the left portion it is continued back as far as the posterior border of the left lobe-or evta a little way on to its superior surface-whence it passes to the diaphragm as the inferior laye of the left triangular ligament. The middle region of the under surface it clothes only as far a the porta hepatis and the fossa of the ductus venosus; from those the peritoneum is carried dow as the anterior layer of the lesser omentum.

The peritoneum, which passes back on the inferior surface of the diaphragm to the left of thị liver, is continued down on the posterior abdominal wall, behind the fundus of the stomach and the spleen, until the left kidney is reached. It covers the superior and lateral part of the kidney. and is then carried forwards as the lieno-renal ligament to the spleen, around which it pass -clothing its renal, phrenic, and gastric surfaces-as far as the hilum (Fig. 966); from that is carried to the stomach as the left layer of the gastro-splenic ligament. Similarly, the inferior layer of the left triangular ligament is continued down on the posterior part of the diaphragm to the oesophagus, the anterior and left sides of which it clothes. It also forms a little fold at the left of the oesophagus, known as the gastro-phrenic ligament (see p. 1241 and Fig. 969).

At the right side, the portion of the peritoneum which forms the inferior layer of the coronary ligament is carried down over the right kidney (and inferior part of the supra-renal gland) to the duodenum and right colic flexure, over both of which it passes.

We shall now follow down the peritoneum forming the posterior wall of the general peritoneal cavity-which we have already traced to the stomach-as seer in a sagittal section (Fig. 964).

Having reached the lesser curvature of the stomach, it passes down over the front of that organ, clothing it completely as far as the greater curvature. Fron that it descends, and is usually adherent to the transverse colon, forming the anterior layer of the gastro-colic ligament. Thence it passes onwards as th most anterior fold of the greater omentum. Arrived at the inferior border of the greater omentum, the membrane returns on itself, and passes upwards towards the transverse colon, forming the most posterior layer of that omentum. After meeting and covering the posterior aspect of the transverse colon (Fig. 964), it is then continued, as the posterior layer of the transverse mesocolon, to the posterior abdominal wall, which it reaches at the anterior border of the pancreas (Fig. 969).

From the anterior border of the pancreas it is continued downwards again clothing first the lower surface of the pancreas, then the front of the third portion of the duodenum, and, below that, the posterior abdominal wall. From the latter however, it is soon carried forwards again by the branches of the superior mesenteric vessels passing to the small intestine. Running out along those, it forms the superior (or, more correctly, the right) layer of the obliquely placed mesentery (Fig. 964): on reaching the small bowel at the border of the mesentery, it invests that tube, giving it its serous coat, and then returns-as the inferior, or left, layer of the mesentery-to the posterior abdominal wall, on which it runs down, covering the great vessels near the median plane, and the psoas major muscle and ureter at each side, to enter the pelvis. The mesentery is described at p. 1208.

Pelvic Peritoneum.-The arrangement of the peritoneum in the pelvis minor

s somewhat complicated, and is fully described in connexion with the several pelvic organs. A general account will suffice here.

Having passed over the superior aperture all round, it enters the pelvis minor, ind covers its walls as low as the pelvic floor, across which it passes to the various organs. Behind, it invests the pelvic colon completely, and forms a mesentery pelvic mesocolon) for it, as far down as the third sacral vertebra. There the colon oins the rectum proper, and the complete investment of the bowel ceases.

As the end of the pelvic colon is approached the two layers of its mesocolon ecome shorter, and when the rectum is reached, they separate, leaving its posterior Eurface uncovered, whilst the bowel is clothed in front and at the sides. Lower down, the membrane leaves the sides, and finally, at a point which is usually about 3 inches (7.5 cm., see p. 1224) above the anus, it leaves the anterior surface of the Dowel, and in the male is carried on to the posterior part of the bladder (here covered

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Ending of pelvic mesocolon

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Second sacral vertebra

[graphic]

Crescentic fold of peritoneum (rectogenital fold) Seminal vesicle beneath this

External iliac

vein

Pararectal fossa

Ureter (cut)

External iliac artery

Rectum

Inferior epigastric artery

6647

Ureter

Paravesical fossa

Plica vesicalis transversa

Rectus

Pyramidalis

Sacral nerves

Urinary bladder

Pararectal fossa

Ureter (cut)
Hypogastric artery
Obturator nerve

-Ureter

Ductus deferens

Obliterated umbilical artery

Iliacus

External iliac artery

Fossa -obturatoria (Waldeyer)

Median umbilical ligament (urachus)

FIG. 965. THE PERITONEUM OF THE PELVIC CAVITY.

The pelvis of a thin male subject aged 60 was sawn across obliquely. Owing to the absence of fat the various pelvic organs are visible through the peritoneum, though not quite so distinctly as represented here. The urinary bladder and rectum were both empty and contracted; the paravesical and pararectal fossæ, as a result, are very well marked,

by the seminal vesicles and deferent ducts), forming the floor of the excavatio recto-vesicalis (recto-vesical pouch), between those organs. It then covers the superior surface of the bladder, and passing off from its sides to the walls of the pelvis, constitutes the so-called false ligaments of the bladder. From the apex of the bladder it is carried on to the anterior abdominal wall by the middle umbilical ligament, thus forming the plica pubovesicalis (O.T. the superior or anterior false ligament of the bladder).

In the female (Fig. 964), the peritoneum, on leaving the rectum, passes to the posterior wall of the vagina, the superior portion of which it covers. From that it is continued up over the posterior surface and fundus of the uterus, and down on its anterior surface as far as the junction of the cervix and body (Fig. 964). Here it passes from the uterus to the bladder, which it partly covers, as in the male, and is then carried on to the anterior abdominal wall. Between the rectum behind, and the uterus and vagina in front, is situated the excavatio rectouterina [cavum Douglasi] (O.T. pouch of Douglas), the entrance of which is limited, on each side,

by a fold passing from the cervix of the uterus around the sides of the pouch towards the rectum; these are the plica rectouterinæ [Douglasi] (O.T. folds of Douglas and they contain in their interior the musculi rectouterini (O.T. utero-sacral ligaments), two bands of fibrous tissue with plain muscle fibres intermixed, which pass from the cervix of the uterus, backwards on each side of the rectum, to blend with the connective tissue on the front of the lower part of the sacrum.

Similarly, in front of the uterus, between it and the bladder, is found the much smaller excavatio vesicouterina (utero-vesical pouch). Finally, the peritoneum is prolonged as a wide fold from each margin of the uterus to the side wall of the pelvis, constituting the ligamentum latum uteri (broad ligament of the uterus). within which are contained the uterine tube, the ovary, the ligamentum teres, and other structures (see pp. 1315 et seq.).

When the bladder is empty, there is seen at each side, between it and the pelvic wall, a considerable peritoneal depression-the paravesical fossa (Fig. 965). This fossa is traversed by a peritoneal fold-the plica vesicalis transversa-which runs transversely laterally from the superior surface of the empty bladder, and, when well marked, passes to the neighbourhood of the abdominal inguinal ring,

Above the bladder, on each side of the middle umbilical ligament, is found the internal inguinal fovea already referred to (p. 1235). Both of these fossæ are practically obliterated by distension of the bladder.

Similarly, there is seen at each side of the empty rectum, on the posterior pelvic wall, a large depression, which may be known as the pararectal fossa (Fig. 965). When the rectum is empty and contracted, these fosse are occupied by intestine; during distension, the rectum, increasing in width, expels the intestine and practically obliterates the fossa.

Transverse Tracing of the Peritoneum.-If the peritoneum is followed transversely around the abdomen, just above the level of the iliac crest (Fig. 968), few difficulties will be encountered. From the anterior abdominal wall it passes round on each side to the back, lining the sides and the posterior wall. Passing medially on the posterior wall, it meets the colon-ascending on the right side, descending on the left-over which it is carried, in each case covering the bowel in front and at the sides only, and leaving the posterior surface bare, as a rule. Sometimes, however, the covering is complete, and a short mesentery is formed. It is next continued medially over the psoas muscles, the ureters, and the great vessels, on the front of which it meets the superior mesenteric artery and vein running downwards to the intestines. From both sides it passes forwards on these vessels, forming the right and left layers of the mesentery; and finally, having reached the intestine, it clothes it completely, and the two portions become continuous on the bowel.

A transverse tracing at a higher level would include the bursa omentalis; it will, therefore, be well to study this portion of the peritoneal cavity before describing such a tracing.

Bursa Omentalis (O.T. Lesser Sac of the Peritoneum).—The omental bursa, as already pointed out, is a diverticulum of the great sac. It lies behind the stomach and adjacent organs, and communicates with the general cavity by a constricted passage, called the foramen epiploicum [Winslowi]. If the general cavity is compared, as already suggested, to a bag, the anterior layer of which clothes the anterior wall and sides of the abdomen, and the posterior layer covers the viscera lying on the posterior wall, the bursa omentalis would correspond to a pocket lying behind the stomach, lesser omentum and part of the liver, and opening into its cavity by a narrow mouth, on the right side, just below the liver. From this opening the pocket passes to the left behind the lesser omentum and stomach, as far as the spleen, up behind the caudate lobe of the liver, and down behind the stomach and gastro-colic ligament.

As in the case of the general peritoneal cavity, it will, of course, be understood that the two walls of the bursa omentalis and the boundaries of the epiploic foramen are normally in contact. We shall first consider this opening, and then trace the layers of the omental bursa.

Foramen Epiploicum (Winslowi) (Fig. 966).-This, the constricted passage which leads from the general peritoneal cavity into the bursa omentalis, is situated just below and behind the porta hepatis. It is bounded anteriorly by the right, free

border of the hepato-duodenal ligament, passing up from the superior part of the duodenum to the porta hepatis, and containing between its two layers the portal vein, hepatic artery, and bile-duct. Posteriorly, lies the inferior vena cava, covered, of course, by peritoneum. Above, is placed the caudate process of

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Omental bursa

[graphic]
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4131

Gastro-splenic
ligament

Spleen

Lieno-renal ligament

Left kidney

Diaphragm

Great sac

Great sac Gastro-splenic ligament Lieno-renal ligament

Stomach

Left kidney

Pancreas
Left supra-renal gland

Aorta

FIG. 966.-TRANSVERSE SECTION OF ABDOMEN AT LEVEL OF EPIPLOIC FORAMEN.

the liver. And below, lies the superior part of the duodenum with the hepatic artery running forwards and to the right beneath the foramen, before turning up into the lesser omentum. It should be remembered that, normally, the various boundaries of the foramen lie in contact, and that its cavity can only be said to exist as such when its walls are drawn apart.

Beyond the foramen epiploicum is a small portion of the omental bursa

Omental bursa

Falciform ligament

Aorta

Liver

Inferior

Right kidney
Inferior vena cava

Epiploic foramen

Duodenum; superior part

Liver

Gastro-duodenal artery

Bile-duct

Great sac

Right kidney

Right supra-renal gland
Inferior vena cava

Portal vein

FIG. 967.-TRANSVERSE SECTION OF ABDOMEN IMMEDIATELY BELOW EPIPLOIC FORAMEN.

termed the vestibulum bursæ omentalis, lying below the processus caudatus of the caudate lobe of the liver, and above the superior part of the duodenum and the head of the pancreas. The anterior wall of this portion is formed by the hepatoduodenal ligament, with the bile-duct, hepatic artery, and portal vein. The

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