The peritoneal cavity

Question 1

What is the peritoneum?

Answer 1

The abdominal cavity is lined by a simple squamous epithelium.
Made up of the visceral (around organs) and parietal (abdominal wall)

Question 2

What is the visceral peritoneum?

Answer 2

Covers the bowel and mesentery
The visceral peritoneum has the same autonomic nerve supply as the viscera it covers. Unlike the parietal peritoneum, pain from the visceral peritoneum is poorly localised and the visceral peritoneum is only sensitive to stretch and chemical irritation. Pain is referred to the associated dermatome.

Question 3

What is the parietal peritoneum?

Answer 3

Covers inside of abdominal wall
It receives the same somatic nerve supply as the region of the abdominal wall that it lines; therefore, pain from the parietal peritoneum is well localised. Parietal peritoneum is sensitive to pressure, pain, laceration and temperature.

Question 4

What is the parietal cavity?

Answer 4

Potential space between the parietal and visceral peritoneum
Normally contains a thin layer of fluid which acts as a lubricant, enabling free movement of the abdominal viscera, and the antibodies in the fluid fight infection.

Question 5

What is Ascites?

Answer 5

Ascites is the abnormal buildup of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity. Symptoms may include increased abdominal size, increased weight, abdominal discomfort, and shortness of breath. Complications can include spontaneous bacterial peritonitis

Question 6

What’s the difference between intra and retro peritoneal?

Answer 6

Some parts of the gastrointestinal tract are suspended by a mesentery and are able to move quite freely (intraperitoneal) whilst others are more firmly attached (retroperitoneal).

Question 7

Which organs are intraperitoneal?

Answer 7

Intraperitoneal organs are enveloped by visceral peritoneum.
Can be remembered as:
Stand - Stomach and Spleen
In - Ileum
Great Britain - Gallbladder
Look - Liver
Jubilantly - Jejunum
To Clouds - Transverse Colon

Question 8

Which organs are retroperitoneal?

Answer 8

Retroperitoneal organs are not associated with visceral peritoneum; they are only covered in parietal peritoneum, and that peritoneum only covers their anterior surface.
Can be remembered as:
S = Suprarenal (adrenal) Glands
A = Aorta/IVC
D =Duodenum (except the proximal 2cm, the duodenal cap)
P = Pancreas (except the tail)
U = Ureters
C = Colon (ascending and descending parts)
K = Kidneys
E = (O)esophagus
R = Rectum

Question 9

What is the mesentery?

Answer 9

A mesentery is a double layer of visceral peritoneum. It connects an intraperitoneal organ to (usually) the posterior abdominal wall. It provides a pathway for nerves, blood vessels and lymphatics to travel from the body wall to the viscera.

Question 10

What is the function of the mesentery?

Answer 10

Suspends the small and large intestine from the posterior abdominal wall; anchoring them in place, whilst still allowing some movement.
Provides a conduit for blood vessels, nerves and lymphatic vessels.
Postulated to play a pathological role in inflammatory diseases such as Crohn’s disease.

Question 11

What is the blood supply of the mesentery?

Answer 11

The superior and inferior mesenteric arteries arise from the abdominal aorta and travel in the mesentery to supply the abdominal viscera. These vessels also give rise to branches that supply the mesentery itself.

Question 12

What are the omenta?

Answer 12

The omenta are sheets of visceral peritoneum that extend from the stomach and proximal part of the duodenum to other abdominal organs.

Question 13

What are the features of the greater omentum?

Answer 13

The greater omentum consists of four layers of visceral peritoneum. It descends from the greater curvature of the stomach and proximal part of the duodenum, then folds back up and attaches to the anterior surface of the transverse colon.
It has a role in immunity and is sometimes referred to as the ‘abdominal policeman’ because it can migrate to infected viscera or to the site of surgical disturbance.

Question 14

What are the features of the lesser omentum?

Answer 14

The lesser omentum is a double layer of visceral peritoneum, and is considerably smaller than the greater and attaches from the lesser curvature of the stomach and the proximal part of the duodenum to the liver.
It consists of two parts: the hepatogastric ligament (the flat, broad sheet) and the hepatoduodenal ligament (the free edge, containing the portal triad).

Question 15

What is the Gastrocolic ligament?

Answer 15

Gastrocolic ligament: a portion of the greater omentum that stretches from the greater curvature of the stomach to the transverse colon. It forms part of the anterior wall of the lesser sac.

Question 16

What is the Splenorenal ligament?

Answer 16

Splenorenal ligament: derived from the peritoneum, where the wall of the general peritoneal cavity comes into contact with the omental bursa between the left kidney and the spleen

Question 17

What is the Hepatoduodenal ligament?

Answer 17

Hepatoduodenal ligament: the portion of the lesser omentum extending between the porta hepatis of the liver and the superior part of the duodenum. Running inside it are the following structures collectively known as the portal triad

Question 18

What is the Gastrosplenic ligament?

Answer 18

Gastrosplenic ligament: made of peritoneum that connects the greater curvature of stomach with the hilum of the spleen.

Question 19

What is the Hepatogastric ligament?

Answer 19

Hepatogastric ligament: connects the liver to the lesser curvature of the stomach. It contains the right and the left gastric arteries. In the abdominal cavity it separates the greater and lesser sacs on the right.

Question 20

What is the Falciform ligament?

Answer 20

Falciform ligament: attaches the liver to the front body wall, and separates the liver into the left medial lobe and left lateral lobe.

Question 21

What is the midline median umbilical ligament?

Answer 21

Midline median umbilical ligament: a midline tubular structure that stretches from the apex of the bladder and connects to the umbilicus. A vestigial remnant of two embryonic structures: the cloaca and the allantois.

Question 22

What is the medial umbilical ligament?

Answer 22

Medial umbilical ligaments: a paired structure found in human anatomy. It is on the deep surface of the anterior abdominal wall, and is covered by the medial umbilical folds. Remnant of the umbilical arteries.

Question 23

What is ligamentum teres?

Answer 23

Ligamentum teres: the remnant of the umbilical vein that exists in the free edge of the falciform ligament of the liver.

Question 24

What is the left triangular ligament?

Answer 24

Left triangular ligament: connects the posterior part of the upper surface of the left lobe of the liver to the diaphragm; its anterior layer is continuous with the left

Question 25

What is the greater sac?

Answer 25

The greater sac is the larger portion of the peritoneal cavity. It is further divided into two compartments by the mesentery of the transverse colon (known as the transverse mesocolon):
Supracolic compartment – lies above the transverse mesocolon and contains the stomach, liver and spleen.
Infracolic compartment – lies below the transverse mesocolon and contains the small intestine, ascending and descending colon.

Question 26

What is the lesser sac?

Answer 26

The lesser sac lies posteriorly to the stomach and lesser omentum. It allows the stomach to move freely against the structures posterior and inferior to it.

Question 27

What is the epiploic foramen?

Answer 27

The lesser omentum is connected with the greater sac through an opening in the lesser omentum – the epiploic foramen (of Winslow).
The epiploic foramen is situated posterior to the free edge of the lesser omentum (the hepatoduodenal ligament).

Question 28

What is the porta hepatis?

Answer 28

Where two major blood vessels enter the liver, the portal vein and the hepatic artery and the bile leaves the liver in the bile duct. These three structures together are the portal triad and run in the free edge of the lesser omentum.

Question 29

What determines the ability to palpate an organ?

Answer 29

If something is above the costal margin e.g. spleen, left lobe of the liver it cannot be palpated transabdominally.

Question 30

How do infections spread in the abdomen?

Answer 30

Once bacteria are in the cavity they can spread rapidly and widely. The tend to ‘gravitate’ to the lowest place which is behind the right lobe of the liver when lying flat and into the pelvis when upright. Tumours may also spread through the cavity.

Question 31

How does Peritoneal dialysis work?

Answer 31

Peritoneal dialysis can occur because the peritoneum is semi-permeable (small molecules can pass through but larger molecules like proteins cannot). In patients with renal failure, it may be possible to draw waste products from the blood into the peritoneal cavity and then drain them out of the cavity.

Question 32

How does the mobility of an organ affect the presentation of disease in that organ?

Answer 32

Mobile parts of the abdominal contents, like the ileum or appendix will move with the movement of the body and breathing. Diseases which cause inflammation of the surface of these organs will cause pain on moving and breathing. Organs that are fixed such as the kidney will not produce pain with movement.

Question 33

With the patient in a supine position, where might fluid collect in the abdomen?

Answer 33

Posterior to the liver

Question 34

Where does the base of the appendix lie (surface marking and internally)?

Answer 34

2/3 of the way from the umbilicus to the anterior superior iliac spine, McBurnies point.

Question 35

Which parts of the bowel have a mesentery?

Answer 35

The first 1cm of duodenum, all of the jejunum and ilium, the transverse and sigmoid colon and the appendix.