Anatomy 10

Question 1

What is the parietal peritoneum?

Answer 1

Lines the abdominal wall.

• It can be seen with naked eye and is innervated by the somatic nerves that supply the overlying muscles and skin of the abdominal wall.
• Pain from the parietal peritoneum is usually sharp, severe, and well localised to the abdominal wall.

Question 2

What is the visceral peritoneum?

Answer 2

Covers the abdominal viscera.

• It is adhered to the surface of the viscera and cannot be seen with the naked eye.
• The visceral peritoneum is innervated by visceral sensory nerves. These nerves convey ‘painful’ sensations back to the CNS along the path of the sympathetic nerves that innervate the organ/structure it covers.
• Pain from the visceral peritoneum can be severe. It is usually dull and diffuse (i.e. it cannot be pinpointed to a specific location).
• ‘Painful’ sensations from the visceral peritoneum may be perceived as nausea or distension.

Question 3

Where does the peritoneal cavity lie?

Answer 3

Between the parietal and visceral peritoneum

Question 4

In a healthy abdomen what lies in the peritoneal cavity and what does it do?

Answer 4

Peritoneal fluid
Allows the viscera to slide freely alongside each other

Question 5

What is meant by intraperitoneal?

Answer 5

Almost completely covered by peritoneum e.g. the stomach

Question 6

What is meant by retroperitoneal?

Answer 6

Posterior to the peritoneum, hence only covered by peritoneum on their anterior surface e.g. the pancreas and abdominal aorta.

Question 7

What is meant by secondarily retroperitoneal?

Answer 7

These organs were intraperitoneal in early development but came to be ‘stuck down’ onto the posterior abdominal wall.

Question 8

What do the Mesenteries, Omenta, Ligaments, Folds do?

Answer 8

• They are all composed of peritoneum and connect organs to each other and to the abdominal wall.
• They may carry blood vessels, nerves, and lymphatics to the viscera.
• They contain a variable amount of fat; some are usually very fatty (the omenta).

Question 9

What are the mesenteries?

Answer 9

Folds of peritoneum that contain fat and suspend the small
intestine and parts of the large intestine from the posterior abdominal wall.

Arteries that supply the intestine (from the abdominal aorta) and veins that drain the gut (tributaries of the portal venous system) are embedded in the mesenteries.

Question 10

What are the greater and lesser omenta?

Answer 10

Folds of peritoneum that are usually fatty and connect the stomach to other organs.

• The greater omentum hangs from the greater curvature of the stomach and lies superficial to the small intestine.
• The lesser omentum connects the stomach and duodenum (the first part of the small intestine) to the liver. The hepatic artery, the hepatic portal vein, and the bile duct (the ‘portal triad’) are embedded within its free edge.

Question 11

What are ligaments?

Answer 11

Folds of peritoneum that connect organs to each other or to the
abdominal wall.

Question 12

What is the falciform ligament?

Answer 12

Connects the anterior surface of the liver to the anterior abdominal wall

Question 13

What are the coronary and triangular ligaments?

Answer 13

Connect the superior surface of the liver to the diaphragm.

Question 14

What are the peritoneal folds?

Answer 14

Raised from the internal aspect of the lower abdominal wall and
are created by the structures they overlie.

Sometimes they are difficult to see

Question 15

What are the median umbilical folds?

Answer 15

Lie in the midline and represents the remnant of the urachus, an embryological structure that connected the bladder to the
umbilicus.

Question 16

What are the medial umbilical folds?

Answer 16

Found lateral to the median umbilical fold

These represent the remnants of the paired umbilical arteries, which returned venous blood to the placenta in foetal life.

Question 17

What are the lateral umbilical folds?

Answer 17

Found lateral to the medial umbilical folds

The inferior epigastric arteries lie deep to these peritoneal folds. They supply the anterior abdominal wall.

Question 18

What is the peritoneal cavity divided into?

Answer 18

The smaller lesser sac
The larger greater sac

Question 19

What is the smaller lesser sac?

Answer 19

(also called the omental bursa) is a space that lies posterior to the stomach and anterior to the pancreas.

Question 20

What is the larger greater sac?

Answer 20

Remaining part of the peritoneal cavity.

• The greater and lesser sacs communicate with each other via a passageway that lies posterior to the free edge of the lesser omentum, the epiploic foramen (also called the omental foramen).

Question 21

What does the gastrointestinal system develop from?

Answer 21

Develops from the embryonic gut tube which lies in the midline of the abdominal cavity, suspended from the posterior abdominal wall by the dorsal mesentery.

Question 22

What does the dorsal mesentery do?

Answer 22

Major branches of the abdominal aorta that supply the developing gut tube travel through the dorsal mesentery

Question 23

What does the ventral mesentery do?

Answer 23

Connects the stomach to the anterior abdominal wall. As the liver grows within it, the anterior part of the ventral mesentery becomes the falciform ligament and the posterior part becomes the lesser omentum.

Question 24

What did the growth, migration and rotation of organs during development cause?

Answer 24

Responsible for the formation of the lesser sac and results in some organs being ‘pushed’ onto the posterior abdominal wall and becoming retroperitoneal.

Question 25

What is peritonitis?

Answer 25

Peritonitis describes infection and inflammation of the peritoneum.

It may be localised or generalised (affecting the whole peritoneum).

Peritonitis may be caused by inflammation of an organ (e.g. the pancreas) or rupture of a hollow viscus (e.g. the 19 stomach or bowel).

Rupture of the intestine allows faecal matter and bacteria to
contaminate the peritoneum.

Because the peritoneum has a large surface area and is semi-permeable, peritonitis can lead to sepsis and is hence a life-threatening condition. Peritonitis is extremely painful.

Question 26

What are peritoneal adhesions?

Answer 26

In a healthy abdomen, a thin layer of peritoneal fluid allows the abdominal viscera to slide freely alongside each other.

Adhesions are pathological fibrous connections between the parietal and visceral peritoneum.

When the peritoneum is irritated (e.g. by infection) it produces fibrin which causes the parietal and visceral peritoneum to adhere to each other.

These connections may become fibrous. They can cause
chronic abdominal pain and they increase the risk of volvulus (twisting) of the intestine, because it can no longer move freely.

Question 27

What is ascites?

Answer 27

Ascites is an increased volume of peritoneal fluid.
It occurs secondary to other pathology, such heart failure, liver failure or intra-abdominal malignancy.

The abdomen may become very distended, and it is very uncomfortable.

An ascitic drain can be used to remove the fluid and relieve symptoms, but fluid will usually reaccumulate.