Abdominal Viscera & Peritoneum

In the development of the gut tube, what does the septum transversum become

the ventral mesentry

Define mesentery

A membranous fold attaching an organ to the body wall

Role of mesenteries and ligaments in the abdomen

provide pathways for vessels, nerves, and lymphatics to travel back and forth between abdominal organs

Location of ventral mesentery

Only found between the foregut and the upper portion of the duodenum

Ventral mesentery is pulled towards which side of the body

Ventral mesentery is pulled towards the right side of the body

What organs are associated with the ventral mesentery

liver

lesser curvature of the stomach

Location of the dorsal mesentery

Extends continuously from the foregut to the end of the hindgut

Dorsal mesentery is pulled towards which side of the body

Dorsal mesentery is pulled towards the left side of the body

What is the Dorsal mesentery associated with (what wall of the abdomen)

The posterior abdominal wall

How does the greater omentum form

The dorsal mesogastrium (attached to the stomach) grows and expands downward, forming a double-layered fold

Double layers of the peritoneum fuse together to form a large apron-like peritoneal fold hanging from the stomach - the greater omentum

What is the lesser omentum

A smaller peritoneal fold connecting the stomach to the liver.

When the anterior abdominal wall is reflected to expose the contents of the abdominal cavity, everything that can be seen is covered in what

peritoneum (thin, serous membrane)

What is the space between the parietal & visceral layers of peritoneum

the peritoneal cavity

What structures/otherwise are in the peritoneal cavity

No structures

Fluid occupies this space to allow movement and mobility of certain organs

The peritoneal cavity can be divided into 2. What are the 2 parts called

Greater sac – main compartment

Lesser sac – hidden from view

Where does the greater sac of the peritoneal cavity extend from & to

Extends from the Diaphragm to Pelvis

Where is the lesser sac of the peritoneal cavity / omental bursa

Posterior to → Stomach & greater omentum

Anterior to → Parietal peritoneum & pancreas

(yellow = lesser sac)

Name of opening between the greater & lesser sacs

The omental foramen / Epiploic foramen / Foramen of Winslow

(provides a direct communication between the greater & lesser sacs)

What is the sexual dimorphism with the peritoneal cavity

Males → Peritoneal cavity is completely closed

Females →There is an opening in the peritoneum through the uterine tubes (fallopian tubes & oviducts)

What parts of the abdominal viscera have a relationship to the peritoneum

All of it

Where is the parietal layer of peritoneum

Covers and lines the internal walls of the abdomen

Pink part of diagram

Where is the Visceral layer of peritoneum

Covers and invests abdominal organs that protrude into the peritoneal cavity

Blue part of diagram

In which layer of peritoneum is pain well localised. In which is it more generalised

Why is that the case?

Parietal = well localised (very sensitive) - Served by the same neurovasculature as the adjacent wall/structure

Visceral = generalised (referred) - Served by the same neurovasculature as the organ it is covering

What are some structures that are formed from peritoneum

Formed from more than one layer of peritoneum:

greater omentum

lesser omentum,

mesentery

peritoneal ligament

Boundaries of the Omental Foramen

Which of these is not a structure that is associated with, or derived from, peritoneum:

Fibrous pericardium

Mesentery

Omenta (greater & Lesser)

Peritoneal ligaments

Peritoneal recesses

Peritoneal fossae

Fibrous pericardium - this is to do with the heart

Role of mesentery

• provide pathways for vessels, nerves, and lymphatics to pass between abdominal organs

• helps to provide a continuous connection between the visceral and parietal peritoneum

• connect organs to the posterior abdominal wall

What is contained within mesentery

Contains fat as well as the arteries, veins, lymphatic vessels, and nerves that supply the abdominal organs

Mesentery are named according to what

the organs they connect

• Mesoesophagus (embryonic)

• Mesogastrium (embryonic)

• The “Mesentery” proper (of small bowel)

• Mesoappendix

• Transverse mesocolon

• Sigmoid mesocolon

How many layers of peritoneum make up the lesser omentum & greater omentum

Lesser = 2 layered peritoneal fold

Greater = 4 layered peritoneal fold

What does the lesser omentum connect

Connects the liver to the LESSER curvature of the stomach and the first part of the duodenum

The lesser omentum can be divided into 2 ligaments - what are they called and what is their structure

What does the greater omentum connect

Connects transverse colon to GREATER curvature of stomach

What does the greater omentum do

name the peritoneal ligaments of the liver

name the peritoneal ligaments of the stomach

name the peritoneal ligaments of the spleen

Ligaments can connect organs to what

Another organ or the abdominal wall

Name the peritoneal recesses

Paracolic gutters

Subphrenic recesses

Subhepatic space

Hepatorenal recess

Location of each of the peritoneal recesses

Paracolic gutters: between the abdominal wall and the lateral aspect of the ascending or descending colon

Subphrenic recesses: Located below the diaphragm

Subhepatic space: Immediately inferior to the liver

Hepatorenal recess: Extension of the subhepatic space between the visceral surface of the liver and the right kidney

Function of Paracolic gutters

Allows communication between the supracolic and infracolic regions of the greater sac

Important for peritoneal fluid flow

Function of Subphrenic recesses

Potential site for fluid collection

Function of Hepatorenal recess

Potential site for fluid collection

Which recess is split into right & left.

What is it split by

Subphrenic recesses

Separated into left and right by the falciform ligament

Abdominal organs can be intraperitoneal or retroperitoneal. What does this mean

Intraperitoneal organs

• almost entirely wrapped in visceral peritoneum

• usually suspended by mesentery in the abdominal cavity

• highly mobile

Retroperitoneal organs

• lie behind the peritoneal cavity with only part of its surface covered by peritoneum.

• generally immobile

Which of these organs is intraperitoneal / retroperitoneal

Stomach

Duodenum

Small Intestine

Transverse colon

Rectum

Liver

Pancreas

Aorta

intraperitoneal | retroperitoneal

Name the intraperitoneal organs

• Stomach

• Liver

• Spleen

• Tail of the pancreas

• Duodenum: 1st part

• Jejunum

• Ileum

• Cecum & appendix

• Transverse colon

• Sigmoid colon

What defines something as primary or secondary retroperitoneal

1° - Primary retroperitoneal structures are retroperitoneal from the start of their development.

2° - Secondary retroperitoneal structures were once suspended within the abdominal cavity by mesentery but migrated posteriorly to end up behind the peritoneum.

Name the primary & secondary retroperitoneal structures of the abdomen

What are infraperitoneal organs

& example

Defined as being beneath the peritoneal cavity

Only part of its surface is covered by peritoneum

E.g. rectum (distal 2/3rds) & urinary bladder

What defines the boundary between supra & infracolic abdominal compartments

the transverse mesocolon

Where is defined as supracolic

Visceral structures below the diaphragm and above the transverse mesocolon

Label these as either supra/infracolic viscera:

Pancreas

Appendix

Liver

Distal esophagus

Rectum

Gallbladder

Large colon

Duodenum

Cecum

Stomach

Spleen

Anus

Small intestine

Split these into foregut, midgut & hindgut:

• Duodenum

• Jejunum

• Stomach

• Pancreas

• Appendix

• Sigmoid colon

• Cecum

• Distal esophagus

• Gallbladder

• Rectum & Anal Canal

• Transverse colon

• Ascending colon

• Spleen*

• Ileum

• Liver

• Descending colon

Arterial supply to foregut

Celiac trunk: Branches from the abdominal aorta at the level of T12

Arterial supply to midgut

Superior mesenteric artery: Branches from the abdominal aorta at the level of L1

Arterial supply to hindgut

Inferior mesenteric artery: Branches from the abdominal aorta at the level of L3

What is peritonitis

Infection can occur if gas, faecal matter or bacteria enter the peritoneal cavity which would result in inflammation of the peritoneum

Can be caused by exudate (fluid/pus that seeped out from an inflamed organ/vessel) , ascitic fluid & paracentesis (surgical puncture of peritoneal cavity)

What are Peritoneal adhesions & examples

fibrous bands that form abnormal connections, e.g.:

▪ Visceral peritoneum attaching to an adjacent organ

▪ Visceral peritoneum attaching to the parietal peritoneum

How do Peritoneal adhesions form

Form as a result of damage (acquired through injury, infection or surgery) to the peritoneal surface when sticky fibrin appears in order to assist with the healing process

Problems & complications with Peritoneal adhesions

Adhesions limit the normal movement of viscera and could lead to complications:

• intestinal obstruction (a.k.a. volvulus)

• Chronic pain

What is a laparotomy

Surgical incision into abdominal cavity prior to major surgery

What is an adhesiotomy

Surgical separation of adhesions

What is an omental bursa herniation

Part of GI tract (usually a loop of the small intestine) can pass through the omental foramen (Epiploic foramen of Winslow) and become twisted and strangulated inside the lesser sac

Is an omental bursa herniation common/rare

rare

What is treatment for an omental bursa herniation

Surgery is required to manually reposition and free the trapped intestinal tract

Boundaries of the omental (epiploic) foramen

what are these

Dark macular spots found on peritoneal layers (visceral & parietal)

From intraperitoneal spillage & spread of India ink from preoperative endoscopic tattooing

At what point is an embryo called a foetus

At week 9

Where does the foregut extend from

From the mouth to the 1st part of the duodenum

Is the peritoneum attached to all of the abdominal wall (anterior & posterior)

It is attached to the complete posterior wall & some of the front

2 layers of peritoneum come together to form what 3 types of structures

a ligament, mesentery, or omentum

largest continuous compartment in the body

Peritoneum

What is the Pringle manoeuvre

a surgical technique used to control bleeding during liver surgery, particularly when there is bleeding from the liver or its vascular structures.

It involves temporarily clamping the hepatoduodenal ligament, which contains the portal vein, hepatic artery, and common bile duct. By clamping this ligament, blood flow to the liver is reduced, which helps control bleeding from the liver, especially during procedures like liver resections or trauma surgery.

The maneuver is often used to determine whether the source of bleeding is from the liver itself or from other areas, such as the surrounding blood vessels. If bleeding stops when the Pringle maneuver is applied, the bleeding is likely from the liver's blood supply. If bleeding continues, the source may be outside of the liver (e.g., from the retroperitoneum).

Some organs are connected to the abdominal wall by a mesentery and can move within the abdominal cavity. Name some of these organs

Small intestine

Transverse colon

Sigmoid colon

Appendix

The gastrocolic ligament connects the stomach to what

The transverse colon

The Falciform ligament connects the liver to what

anterior abdominal wall and the diaphragm

Which ligament is important in hypertension

The coronary ligament

Which organs have mesentery and which don’t (which groups of organs)

Intraperitoneal organs have mesentery

Retroperitoneal organs don’t have mesentery

The embryonic aorta has how many unpaired branches

Name them

The embryonic aorta has 3 unpaired branches:

the celiac trunk

the superior mesenteric artery

the inferior mesenteric artery

The appendix is associated with what dermatone

T10