Peritoneum and Peritoneal Cavity

Question 1

Define peritoneum, and identify the main types of it.

Answer 1

Peritoneum is a thing serous membrane.

• Parietal peritoneum lines the walls of the abdominal and pelvic cavities
• Visceral peritoneum covers the viscera

Question 2

State the name of the potential space present between the parietal and visceral peritoneum. Is this potential space open or closed ? What is the significance of this ?

Answer 2

Peritoneal cavity
In men, this potential space is completely closed
In women, the peritoneal cavity has a potential indirect communication with the exterior (hence infection can spread from the exterior into the peritoneal cavity in women)

Question 3

Identify the main parts of the peritoneal cavity, describing the location of each.

Answer 3

• Greater sac: Main compartment, extending from the diaphragm to the pelvis
• Lesser (omental bursa) sac: located posterior to the stomach and lesser omentum, but extends slightly into the greater omentum.

Question 4

Identify the liquid secreted by the peritoneum. What is the function of this liquid ?

Answer 4

The peritoneum secretes a small amount of serous fluid known as the peritoneal fluid

The peritoneal fluid lubricates the surfaces of the peritoneum to allow distention and free movement between the viscera (organs)

Question 5

What structures does the peritoneum make up ?

Answer 5

The peritoneum makes up the mesentries, the omenta (greater and lesser), and ligaments

Question 6

Describe a clinical significance of the peritoneal cavity.

Answer 6

• Peritoneal cavity can be used for peritoneal dialysis or fluid administration.
• Infection, bleeding, and other cells can spread through this cavity

Question 7

How do the greater and lesser sacs making up the peritoneal cavity communicate with each other ? What is the clinical significance of this ?

Answer 7

The greater and lesser sacs making up the peritoneal cavity communicate with each other via the epiploic foramen (i.e. omental foramen, i.e. foramen of Winslow).
Lesser sac can be approached during surgery via the omental foramen (e.g. if need to operate on pancreas)

Question 8

Describe the lesser omentum, especially in terms of:

• parts
• derived from
• path

Answer 8

LESSER OMENTUM

• Derived from ventral mesentery (i.e. anterior to the gut tube)
• Path: passes from lesser curvature of stomach and first part of duodenum to the inferior border of the liver
• Parts: hepatogastric and hepatoduodenal ligaments (latter is free edge of the lesser omemtum)

Question 9

Identify the contents of the hepatoduodenal ligament.

Answer 9

The hepatoduodenal ligament contains the portal triad:

• Hepatic portal vein
• Hepatic artery proper
• Common bile duct

Question 10

Identify a clinical method used if bleeding occurs as a result of attempted access through the omental foramen.

Answer 10

Pringle’s manoeuvre: during surgery, the hepatic artery proper and the portal vein can be compressed with fingers/haemostat to control bleeding.

Question 11

Identify the boundaries of the epiploic foramen.

Answer 11

Anterior: Hepatoduodenal ligament
Posterior: IVC
Superior: Caudate process of the caudate lobe of the liver
Inferior: First part of the duodenum

Question 12

Describe the greater omentum, especially in terms of:

• where derived from
• path
• parts

Answer 12

GREATER OMENTUM

• Derived from the dorsal mesentery (posterior to the gut tube)
• Path: attached to the greater curvature of the stomach, and first part of duodenum, hangs like an apron anterior to the small intestine, overlies the transverse colon and much of the small intestine.
• Parts: Double layer of visceral peritoneum folded upon itself

Question 13

True or false: the greater omentum contains fat.

Answer 13

True, the greater omentum does contain fat.

Question 14

What structure is known as the policeman of the abdomen ? Why ?

Answer 14

Greater omentum is the policeman of the abdomen.

If infection, greater omentum tries to wrap around it and contain it. If perforation, plugs perforation.

Question 15

Describe the mesentery, especially:

• where it is derived from
• what it is
• function
• location/path
• other special features

Answer 15

MESENTERY

• Derived from dorsal mesentery (posterior to the gut tube)
• Fan shaped tissue formed by a double layer of visceral peritoneum
• Function: Attach the jejunum and ileum to the posterior abdominal wall + conduit for branches of the superior mesenteric vessels, nerves, and lymphatics
• Location/path: its base starts just left of L2 and passes obliquely downward to the right ending just above the sacroiliac joint. It crosses the 3rd part of the duodenum, the aorta, and IVC, the right gonadal vessels, and right ureter
• Mesentery of the small intestine only referred to as the mesentery, but mesentery of other abdominal organs should be named according to corresponding organ (mesocolon, mesoappendix)

Question 16

How long is the mesentery ?

Answer 16

20 cm long

Question 17

Describe the sigmoid mesolon, especially:

• What it is
• Function
• Location/path

Answer 17

SIGMOID MESOLON

• Double layered fold of visceral peritoneum
• Function: connects the sigmoid colon to the posterior abdominal wall + transmits the sigmoid branches of the inferior mesenteric vessels along with nerves and lymphatics
• Location/path: Its root is in the iliac fossa + crosses the bifurcation of the left common iliac vessels, and crosses the left ureter

Question 18

Describe the function and location/path of the transverse mesocolon.

Answer 18

TRANSVERSE MESOCOLON

• Function: suspends transverse colon from the posterior abdominal wall + carries branches of the middle colic vessels
• Location/path: root is just inferior to the pancreas

Question 19

What compartments does the transverse mesocolon divide the peritoneal cavity (greater sac) into ?

Answer 19

The transverse mesocolon divides the greater sac into infracolic and supracolic compartments.

Question 20

What does the infracolonic compartment (created by the transverse mesocolon) contain ?

Answer 20

The infracolonic compartment contains duodenum, jejunum, ileum, ascending, and descending colon.

Question 21

What does the supracolonic compartment contain ?

Answer 21

The supracolic compartment contains duodenum, liver, gall bladder, stomach and spleen.

Question 22

Name the communication between infracolic and supracolic compartments. How is this created ?

Answer 22

The infracolic and supracolic compartments communicate through the paracolic gutters (grooves between the lateral aspects of the ascending or descending colon and the posterolateral abdominal wall).
Peritoneal reflections creates recesses, spaces, and gutters.

Question 23

Explain the clinical important of paracolic gutters.

Answer 23

If there is peritoneal fluid present (infection, abscess, blood), then these paracolic gutters will lead the fluid into certain sites.

• If patient is supine, fluid can accumulate in pelvic cavity of R posterior subhepatic space.
• If patient is recumbant, fluid can accumulate in pelvic cavity.

Question 24

Give the other names of the R posterior subhepatic space, describe its location, and explain its clinical importance.

Answer 24

• R posterior subhepatic space, also known as hepatorenal recess, also known as Morisson’s pouch.
• Located as part of the peritoneal cavity, on the R side between the liver and the right kidney and right suprerenal gland.
• Most patients in hospital are bed ridden, so in supine position. Consequently, the right posterior subhepatic space is the most likely site of infection/fluid accumulation.

Question 25

Explain what would happen if an excess amount of fluid were to flow into the R posterior subhepatic space (too much for it to be contained there).

Answer 25

Since the R posterior subhepatic space and the subphrenic recess are continuous anteriorly, the excess fluid would flow into this subphrenic recess.

Question 26

Explain where fluid would accumulate if the patient were to be in semi-recumbent position.

Answer 26

Fluid would accumulate in the pelvic cavity, starting with the deepest part of this cavity, notably:

• Rectovesical pouch in males (separates the rectum from urinary bladder)
• Rectouterine pouch (of Douglas) in females (separates rectum from uterus)

Females also have a vesicouterine pouch (separate urinary bladder from uterus)

Question 27

Define peritoneal folds, and identify the main peritoneal folds.

Answer 27

♦ A peritoneal fold is a reflection of peritoneum, often formed by peritoneum which covers blood vessels, ducts, or obliterated feotal vessels

♦ On the posterior surface of the anterior abdominal wall, there are:

• median umbilical fold, is the remnant of the urachus that extends from the urinary bladder, to the umbilicus
• 2 medial umbilical folds overlie remnants of the umbilical arteries
• 2 lateral umbilical folds are raised by the inferior epigastric arteries

Question 28

Define peritoneal ligaments.

Answer 28

Peritoneal ligaments are two layered folds of peritoneum that connect two organs together.

Question 29

Identify the main recesses present between the peritoneal folds, stating their location relative to these peritoneal folds.

Answer 29

• Supravesical fossa, on either side of the median umbilical fold
• Medial umbilical fossa, between medial and lateral umbilical folds
• Lateral umbilical fossa, lateral to the lateral umbilical folds

Question 30

What is the significance of the lateral umbilical fossa ?

Answer 30

The lateral umbilical fossa contains the deep inguinal ring.

Question 31

Identify and describe each possible peritoneal relationship.

Answer 31

INTRAPERITONEAL

• Almost totally covered with visceral peritoneum
• Suspended by a mesentery

RETROPERITONEAL

• Lie behind or outside the peritoneum
• Only partially covered with visceral peritoneum

SECONDARY RETROPERITONEAL
-Initially intraperitoneal but migrate retroperitoneally during embryogenesis and lost their mesentery

Question 32

Give examples of intraperitoneal organs.

Answer 32

Abdominal oesophagus
Stomach
First part of dudeonum
Liver
Gall bladder
All small intestine (i.e. jejunum and ileum)
Appendix
Caceum
Sigmoid colon

Question 33

Give examples of retroperitoneal organs.

Answer 33

• Circulatory: Abdominal aorta, IVC
• Digestive: Oesophagus (thoracic part), rectum (middle 1/3 with lower 1/3 totally extraperitoneal)
• Urinary: Suprarenal (adrenal glands), kidneys, ureters, bladder

Question 34

Give examples of secondary retroperitoneal organs.

Answer 34

• Pancreas (except its tail)
• Duodenum (except first part)
• Ascending and descending colon

Question 35

Describe the nerve supply of the parietal peritoneum.

Answer 35

The peritoneum lining the anterior abdominal wall is supplied by the same nerves that supply the overlying skin.
-T7 to L1

The diaphragmatic parietal peritoneum is supplied by the phrenic nerves
-C3 to C5

The pelvic parietal peritoneum is mainly supplied by the obturator nerves
-L2 to L4

Question 36

What sensations is the parietal peritoneum sensitive to ? Where is pain from the parietal peritoneum referred ?

Answer 36

Parietal peritoneum is sensitive to pain (well localised), temperature, touch, and pressure.

Pain from the parietal peritoneum will NOT refer, well-localised pain because pain originating from a certain area will be felt in same dermatome.

Question 37

Describe the nerve supply of the visceral peritoneum.

Answer 37

Visceral peritoneum is supplied by autonomic afferent nerves that also supply the viscera.

Question 38

What sensations is the visceral peritoneum sensitive to ? Where is the pain from the visceral peritoneum referred ?

Answer 38

The visceral peritoneum is sensitive only to stretch and tearing (which causes diffuse and poorly localised pain), but not to touch, pressure, or temperature.

The brain cannot localise visceral pain and this is often referred to a dermatome. Where the pain refers depends on the sympathetic supply of the visceral peritoneum. For instance, stomach receives sympathetics from T6-T9 so pain will refer to T6-T9 dermatomes (on L side since stomach is on the L side), while appendix receives sympathetics from T10 so pain will refer to T10 dermatome (around umbilicus).