thin serous membrane - site.iugaza.edu.pssite.iugaza.edu.ps/eshaqoura/files/abd.cavity-1-peritoneum.pdf · thin serous membrane lining the walls of the abdominal and pelvic cavities

The peritoneum is the thin serous membrane lining the walls of the abdominal and pelvic cavities and covering the abdominal and pelvic viscera.

The peritoneum can be regarded as a balloon into which organs are pressed from outside.

GENERAL ARRANGEMENT OF THE PERITONIUM

In males, this is a closed cavity; but in females, communication with the exterior occurs through the uterine tubes, the uterus, and the vagina.


Between the parietal peritoneum and the

fascial lining of the abdominal and pelvic

walls is a layer of connective tissue called

the extraperitoneal tissue.

It varies in amount in different regions

and, in the area of the kidneys, contains a

large amount of fat.

The visceral peritoneum is closely bound

to the underlying viscus by only a small

amount of connective tissue.



The peritoneal cavity is the largest cavity in the

body, and the surface area of the parietal and

visceral layers is enormous.

peritoneal

cavity

greater sac lesser sac

The greater sac is the

main compartment of

the peritoneal cavity

and extends from the

diaphragm down into

the pelvis.

The lesser sac is

smaller and lies

behind the stomach.


The greater and lesser sacs are in free communication with one another through an oval window called the opening of lesser sac, or the epiploic foramen.

The peritoneum secretes a small amount of serous fluid, the peritoneal fluid, which lubricates the surfaces of the peritoneum and allows free movement between the viscera.


The terms intraperitoneal and

retroperitoneal are used to describe the

relationship of various organs to their

peritoneal covering.

An organ is said to be intraperitoneal if is

almost totally covered with visceral

peritoneum, e.g., stomach, jejunum,

ileum, and spleen.

INTRAPERITONEAL AND RETROPERITONEAL

RELATIONSHIPS

Retroperitoneal organs lie behind the peritoneum and are only partially covered with visceral peritoneum.

The pancreas and the ascending and descending parts of the colon are examples of retroperitoneal organs.

No organ, however, is actually within the peritoneal cavity.

An intraperitoneal organ, such as the stomach appears to be surrounded by the peritoneal cavity but it is covered with visceral peritoneum and is attached to other organs by omenta.

INTRAPERITONEAL AND RETROPERITONEAL

RELATIONSHIPS

PERITONEAL LIGAMENTS

Peritoneal ligaments are two-layered folds of peritoneum that connect solid viscera to the abdominal walls. (They do not possess the dense fibrous tissue seen in ligaments associated with bones).

The liver, for example, is

connected to the diaphragm by the falciform ligament, the coronary ligament, and the right and left triangular ligaments.

OMENTA

Omenta are two-layered folds of peritoneum that connect the stomach to another viscus.

The greater omentum connects the greater curvature of the stomach to the transverse colon.

It hangs down like an apron in front of the coils of the small intestine and is folded back on itself to be attached to the transverse colon.

The lesser omentum suspends the lesser curvature of the stomach from the fissure of the ligamentum venosum and the porta hepatis on the undersurface of the liver.

The gastrosplenic omentum (ligament) connects the stomach to the hilum of the spleen.

OMENTA

MESENTERIES

Mesenteries are two-layered folds of peritoneum connecting parts of the intestines to the posterior abdominal wall, for example, the mesentery of the small intestine, the transverse mesocolon, and the sigmoid mesocolon.

The peritoneal ligaments, omenta, and mesenteries permit blood, lymph

vessels, and nerves to reach the viscera.

PERITONEUM AS SEEN ON TRANSVERSE SECTIONS OF

THE ABDOMEN

At the Level of the Fourth Lumbar Vertebra

The parietal peritoneum lining the anterior abdominal wall below the umbilicus is smooth, apart from the low ridges produced by the:

1. median umbilical ligament (the urachus, the remains of the fetal allantois, which passes from the apex of the bladder to the umbilicus).

2. lateral umbilical ligaments (the obliterated umbilical arteries, which pass from the internal iliac arteries to the umbilicus.

The parietal peritoneum passes onto the posterior abdominal wall and becomes continuous with the visceral peritoneum covering the sides and anterior surfaces of the ascending colon and descending colon.


THE ABDOMEN

In the region of the aorta and inferior vena cava, the parietal peritoneum becomes continuous with the mesentery of the small intestine.

Note that the peritoneum forms a continuous layer that can be traced around the abdominal cavity without interruption.


THE ABDOMEN

At the Level of the Twelfth Thoracic Vertebra

The parietal peritoneum lining the anterior abdominal wall forms a sickle-shaped fold called the falciform ligament.

This connects the anterior surface of the liver to the anterior abdominal wall above the umbilicus and to the diaphragm.


THE ABDOMEN

In the free border of the ligament, where the two layers of peritoneum are continuous with each other, lies the ligamentum teres.

This is the obliterated umbilical vein of the fetus, which passes upward to enter the groove between the quadrate lobe and the left lobe of the liver.


THE ABDOMEN

If the parietal peritoneum is

followed around the

abdominal wall on the left

side, it reaches the lateral

margin of the left kidney.

Here it becomes

continuous with the

visceral peritoneum

covering the lateral margin

and part of the anterior

surface of the left kidney.


THE ABDOMEN

The peritoneum then leaves the kidney and passes to the hilum of the spleen as the posterior layer of

the splenicorenal (lienorenal) ligament.


THE ABDOMEN

The visceral peritoneum covers the spleen and, on reaching the hilum again, is reflected onto the greater curvature of the stomach as the anterior layer of the gastrosplenic omentum (ligament).

The visceral peritoneum covers the anterior surface of the stomach and leaves the lesser curvature to form the anterior layer of the lesser omentum.


THE ABDOMEN

On the right, the lesser omentum has a free border, and here the peritoneum folds around the bile duct, hepatic artery, and portal vein.

The free border of the lesser omentum forms the anterior margin of the opening into the lesser sac.


THE ABDOMEN

The peritoneum forms the posterior layer of the lesser omentum and becomes continuous with the visceral layer of peritoneum covering the posterior wall of the stomach.

Note that here the peritoneum forms the anterior wall of the lesser sac.


THE ABDOMEN

At the greater

curvature of the

stomach, the

peritoneum leaves the

stomach, forming the

posterior layer of the

gastrosplenic

omentum (ligament),

and reaches the hilum

of the spleen.


THE ABDOMEN

Here it is reflected backward to the posterior abdominal wall, forming the anterior layer of the splenicorenal ligament.

The peritoneum now covers the anterior surface of the pancreas, the aorta, and the inferior vena cava, forming the posterior wall of the lesser sac.


THE ABDOMEN

The peritoneum passes onto the anterior surface of the right kidney and sweeps around the lateral abdominal wall to reach the anterior abdominal wall.

Once again, note that the peritoneum forms a continuous layer around the abdomen.


THE ABDOMEN

PERITONEUM AS SEEN ON SAGITTAL

SECTION OF THE ABDOMEN AND PELVIS

The parietal peritoneum lining the anterior abdominal wall can be traced upward to the left of the falciform ligament to reach the undersurface of the diaphragm.

Here, it is reflected onto the upper surface of the liver as the anterior layer of the left triangular ligament.

The visceral peritoneum then covers the anterior and inferior surfaces of the liver until it reaches the porta hepatis.

Here, the peritoneum passes

to the lesser curvature of the

stomach as the anterior layer

of the lesser omentum.

Having covered the anterior

surface of the stomach, the

peritoneum leaves the

greater curvature, forming the

anterior layer of the greater

omentum.

PERITONEUM AS SEEN ON SAGITTAL SECTION OF THE

ABDOMEN AND PELVIS

The greater omentum hangs down as a fold in front of the coils of intestine and contains within it the lower part of the lesser sac.

Having reached the lowest limit of the greater omentum, the peritoneum folds upward and forms the posterior layer of the greater omentum.


ABDOMEN AND PELVIS

On reaching the inferior border of the transverse colon, the peritoneum covers its posterior surface and then leaves the colon to form the posterior layer of the transverse mesocolon.

The peritoneum then passes to the anterior border of the pancreas and runs downward anterior to the third part of the duodenum.


ABDOMEN AND PELVIS

The peritoneum now leaves the posterior abdominal wall as the anterior layer of the mesentery of the small intestine.

The visceral peritoneum covers the jejunum and then forms the posterior layer of the mesentery.


ABDOMEN AND PELVIS

On returning to the posterior abdominal wall, the peritoneum runs downward into the pelvis and covers the anterior surface of the upper part of the rectum.

From here, it is reflected onto the posterior surface of the upper part of the vagina, forming the important rectouterine pouch (pouch of Douglas).


ABDOMEN AND PELVIS

In the male, the peritoneum is reflected onto the upper part of the posterior surface of the bladder and the seminal vesicles, forming the rectovesical pouch.


ABDOMEN AND PELVIS

The peritoneum passes over

the upper surface of the uterus

in the female and is reflected

from its anterior surface onto

the upper surface of the

bladder.

In both sexes, the

peritoneum passes from the

bladder onto the anterior

abdominal wall.

PERITONEAL POUCHES, RECESSES, SPACES,

AND GUTTERS

Lesser Sac

The lesser sac is an extensive peritoneal pouch situated behind the lesser omentum and stomach and lying in front of structures situated on the posterior abdominal wall.

It projects upward as far as the diaphragm and downward between the layers of the greater omentum.

The lower part of

the lesser sac is

often obliterated by

the adherence of

the anterior layers

of the greater

omentum to the

posterior layers.

Lesser Sac

Its left margin

is formed by

the spleen and

the

gastrosplenic

omentum and

splenicorenal

ligaments.

Lesser Sac

Below it is formed by the left free border of the greater omentum.

The right margin of the sac opens into the greater sac—that is, the main part of the peritoneal cavity—through the opening of the lesser sac, or epiploic foramen.

Below the opening, the right margin formed by the right free border of the greater omentum.

Lesser Sac

• Anteriorly: The free border of the lesser omentum, containing the bile duct, the hepatic artery, and the portal vein.

The bile duct lies to the right and in front, the hepatic artery lies to the left and in front, and the portal vein lies posteriorly.

Boundaries of the epiploic foramen

• Posteriorly: The

inferior vena

cava.

• Superiorly: The

caudate process

of the caudate

lobe of the liver.

• Inferiorly: The first

part of the

duodenum.

Boundaries of the epiploic foramen

Close to the duodenojejunal junction may be

four small pocket like pouches of peritoneum

called the superior, inferior, paraduodenal, and

retro duodenal recesses.

Duodenal Recesses

The presence of folds of peritoneum close to the cecum creates three peritoneal recesses: the superior , inferior, and the retrocecal recesses.

These recesses in the peritoneal lining occasionally form deep pouches.

Cecal Recesses

The intersigmoid recess is situated at the apex of the

inverted, V-shaped root of the sigmoid mesocolon.

Its mouth opens downward and lies in front of the left

ureter.

Intersigmoid Recess

The various peritoneal pouches and recesses described in the previous

paragraphs may become sites for the development of internal abdominal

herniae

The existence of the intraperitoneal subphrenic spaces is the result of the complicated arrangement of the peritoneum in the region of the liver.

The right and left anterior subphrenic spaces lie between the diaphragm and the liver, one on each side of the falciform ligament.

Subphrenic Spaces

The right posterior subphrenic space lies between the right lobe of the liver, the right kidney, and the right colic flexure.

The right extraperitoneal space lies between the layers of the coronary ligament and is therefore situated between the liver and the diaphragm.

Subphrenic Spaces

The paracolic gutters lie on the lateral and medial sides of the ascending and descending colons, respectively.

The right medial paracolic gutter is closed off from the pelvic cavity inferiorly by the mesentery of the small intestine, whereas the others are in free communication with the pelvic cavity.

Paracolic Gutters

The right lateral paracolic gutter is in communication with the right posterior subphrenic space, but the left lateral gutter is separated from the area around the spleen by the phrenicocolic ligament, a fold of peritoneum that passes from the left colic flexure to the diaphragm.

Paracolic Gutters

The subphrenic spaces and the

paracolic gutters are clinically

important because they may be sites

for the collection and movement of

infected peritoneal fluid.

Paracolic Gutters

NERVE SUPPLY OF THE PERITONEUM

The parietal peritoneum is sensitive to

pain, temperature, touch, and

pressure.

The parietal peritoneum lining the

anterior abdominal wall is supplied by

the lower six thoracic and first lumbar

nerves—that is, the same nerves that

innervate the overlying muscles and

skin.

The central part of the diaphragmatic

peritoneum is supplied by the phrenic nerves.

The peripheral part of the diaphragmatic

peritoneum is supplied by the lower six thoracic nerves.

The parietal peritoneum in the pelvis is

mainly supplied by the obturator nerve, a

branch of the lumbar plexus.


The visceral peritoneum is sensitive to stretch and tearing and is not sensitive to touch, pressure, or temperature.

It is supplied by autonomic afferent nerves that supply the viscera or are traveling in the mesenteries.

Overdistension of a viscus leads to the sensation of pain.

The mesenteries of the small and large intestines are sensitive to mechanical stretching.


FUNCTIONS OF THE PERITONEUM

The peritoneal fluid, which is pale yellow and somewhat viscid, contains leukocytes.

It is secreted by the peritoneum and ensures that the mobile viscera glide easily on one an other.

As a result of the movements of the diaphragm and the abdominal muscles, together with the peristaltic movements of the intestinal tract, the peritoneal fluid is not static.

Experimental evidence has shown that particulate matter introduced into the lower part of the peritoneal cavity reaches the subphrenic peritoneal spaces rapidly, whatever the position of the body.

It seems that intraperitoneal movement of fluid toward the diaphragm is continuous, and there it is quickly absorbed into the subperitoneal lymphatic capillaries.


This can be explained on the basis that the area of peritoneum is extensive in the region of the diaphragm and the respiratory movements of the diaphragm aid lymph flow in the lymph vessels.

The peritoneal coverings of the intestine tend to stick together in the presence of infection. The greater omentum, which is kept constantly on the move by the peristalsis of the neighboring intestinal tract, may adhere to other peritoneal surfaces around a focus of infection.

In this manner, many of the intraperitoneal infections are sealed off and remain localized.


The peritoneal folds play an important part in suspending the various organs within the peritoneal cavity and serve as a means of conveying the blood vessels, lymphatics, and nerves to these organs.

Large amounts of fat are stored in the peritoneal ligaments and mesenteries, and especially large amounts can be found in the greater omentum.


The peritoneal cavity is divided into an upper part within the abdomen and a lower part in the pelvis.

The attachment of the transverse mesocolon and the mesentery of the small intestine to the posterior abdominal wall provides natural peritoneal barriers that may hinder the movement of infected peritoneal fluid from the upper part to the lower part of the peritoneal cavity.

MOVEMENT OF PERITONEAL FLUID

It is interesting to note that when the patient is in the supine position the right subphrenic peritoneal space and the pelvic cavity are the lowest areas of the peritoneal cavity and the region of the pelvic brim is the highest area.

MOVEMENT OF PERITONEAL FLUID

PERITONEAL INFECTION

Infection may gain entrance to the peritoneal cavity through several routes:

from the interior of the gastrointestinal tract and gallbladder,

through the anterior abdominal wall,

via the uterine tubes in females ,

from the blood.

Collection of infected peritoneal fluid in one of the subphrenic spaces is often accompanied by infection of the pleural cavity.

It is common to find a localized empyerna in a patient with a subphrenic abscess.

It is believed that the infection spreads from the peritoneum to the pleura via the diaphragmatic lymph vessels.

A patient with a subphrenic abscess may complain of pain over the shoulder.

PERITONEAL INFECTION

To avoid the accumulation of infected fluid in the sub phrenic spaces and to delay the absorption of toxins from intraperitoneal infections, it is common nursing practice to sit a patient up in bed with the back at an angle of 45° In this position, the infected peritoneal

fluid tends to gravitate downward into the pelvic cavity, where the rate of toxin absorption is slow.

The greater omentum is often referred to by the surgeons as the abdominal policeman.

The lower and the right and left margins are free, and it moves about the peritoneal cavity in response to the peristaltic movements of the neighboring gut.

In the first 2 years of life it is poorly developed and thus is less protective in a young child.

THE GRAETER OMENTUM LOCALIZATION OF INFECTION

Later, however, in an acutely inflamed appendix, for example, the inflammatory exudate causes the omentum to adhere to the appendix and wrap itself around the infected organ.

By this means, the infection is often localized to a small area of the peritoneal cavity, thus saving the patient from a serious diffuse peritonitis.

GREATER OMENTUM

The greater omentum has been found to plug the neck of a hernial sac and prevent the entrance of coils of small intestine.

Surgeons sometimes use the omentum to buttress an intestinal anastomosis or in the closure of a perforated gastric or duodenal ulcer.

The greater omentum may undergo torsion, and if extensive, the blood supply to a part of it may be cut off, causing necrosis

ASCITES

Ascites is essentially an excessive accumulation of peritoneal fluid within the peritoneal cavity.

Ascites can occur secondary to hepatic cirrhosis, malignant disease, or congestive heart failure.

In a thin patient, as much as 1500 ml has to accumulate before ascites can be recognized clinically.

In obese individuals, a far greater amount has to collect before it can be detected.

PERITONEAL PAIN FROM THE PARITAL PERITONEUM

Abdominal pain originating from the parietal peritoneum is therefore of the somatic type and can be precisely localized; it is usually severe.

An inflamed parietal peritoneum is extremely sensitive to stretching.

This fact is made use of clinically in diagnosing peritonitis.

Pressure is applied to the abdominal wall with a single finger over the site of the inflammation.

The pressure is then removed by suddenly withdrawing the finger.

The abdominal wall rebounds, resulting in extreme local pain, which is known as rebound tenderness.

It should always be remembered that the parietal peritoneum in the pelvis is innervated by the obturator nerve and can be palpated by means of a rectal or vaginal examination.

An inflamed appendix may hang down into the pelvis and irritate the parietal peritoneum.

A pelvic examination can detect extreme tenderness of the parietal peritoneum on the right side.

PERITONEAL PAIN FROM THE PARITAL PERITONEUM

The visceral peritoneum, including the mesenteries, is innervated by autonomic afferent nerves.

Stretch caused by overdistension of a viscus or pulling on a mesentery gives rise to the sensation of pain.

Because the gastrointestinal tract arises embryologically as a midline structure and receives a bilateral nerve supply, pain is referred to the midline.

Pain arising from an abdominal viscus is dull and poorly localized.

PERITONEAL PAIN FROM THE VISAERAL PERITONEUM

PERITONEAL DIALYSIS

Because the peritoneum is a semipermeable membrane,allows rapid bidirectional transfer of substances across it self.

Because the surface area of the peritoneum is enormous, this transfer property has been made use of in patients with acute renal insufficiency.

The efficiency of this method is only a fraction of that achieved by hemodialysis.

A watery solution, the dialysate, is introduced through a catheter through a small midline incision through the anterior abdominal wall below the umbilicus.

The technique is the same as peritoneal lavage.

The products of metabolism, such as urea, diffuse through the peritoneal lining cells from the blood vessels into the dialysate and are removed from the patient.

INTERNAL ABDOMINAL HERNIA

Occasionally, a loop of intestine enters a peritoneal pouch or recess (e.g., the lesser sac or the duodenal recesses) and becomes strangulated at the edges of the recess.

Remember that important structures form the boundaries of the entrance into the lesser sac and that the inferior mesenteric vein often lies in the anterior wall of the paraduodenal recess.

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thin serous membrane - site.iugaza.edu.pssite.iugaza.edu.ps/eshaqoura/files/abd.cavity-1-peritoneum.pdf · thin serous membrane lining the walls of the abdominal and pelvic cavities