W3: Surface markings, peritoneal cavity and peritoneum

Question 1

What is the abdomen proper separated from the pelvis by?

Answer 1

The pelvis inlet

Question 2

How far may the abdominal cavity extend superiorly?

Answer 2

4th intercostal space

Question 3

What can the anterior abdomen be divided into?
What do the quadrants contain?

Answer 3

Either 9 regions or 4 quadrants

9 regions - right hypochondriac, epigastric, left hypochondriac, right lumbar, umbilical, left lumbar, right iliac, hypogastric (suprapubic region), left iliac

Iliac fossa = concave surface of ilium, used to describe quadrant

Quadrants. - right upper (liver + gallbladder), left upper (stomach and spleen), right lower (caecum and appendix), left lower (descending colon and sigmoid)

Question 4

Discuss 9 regions of surface abdo

Answer 4

Horizontal:
• Transpyloric plane – a horizontal line located midway between the suprasternal notch and the upper border of the pubic symphysis, approximately at the level of the lower border of the L1 vertebral body.
• Transtubercular plane – a horizontal line located midway between the transpyloric plane and the upper border of the pubic symphysis, corresponding to the level of the iliac tubercles and the L5 vertebral body

Vertical:
• Right mid-clavicular line - a vertical line extending inferiorly across the trunk from the midpoint of the right clavicle.
• Left mid-clavicular line – a vertical line extending inferiorly across the trunk from the midpoint of the left clavicle.

Question 5

Discuss quadrants of surface abdo. What are they created by?

Answer 5

Vertical line along the mid-line, passing from diploid to pubic symph, and a horizontal line though the umbilicus

Question 6

Causes of right upper quadrant pain

Answer 6

Cholecystitis
Cholangitis
Cholelithiasis
Colitis
Diverticulutis
Hepatic absess
Hepatitis
Kidney stones
Pyelonephritis

Question 7

What is diverticulitis?

Answer 7

Inflammation of pouch of large intestine

Question 8

Summarise causes of pain in different quadrants

Answer 8

Question 9

Causes of left upper quadrant pain

Answer 9

Angina
MI
Pericarditis
Oesophagitis
Gastritis
Peptic ulcer disease
Pancreatitis
Pancreatic cancer
Kidney stones
Pyelonephritis

Question 10

Cause of right lower quadrant pain

Answer 10

Appendicitis
Colitis
Diverticulitis
IBD
Ectopic pregnancy
Uterine fibroids
Ovarian mass
Ovarian torsion
Kidney stones
Pyelonephritis

Question 11

Causes of left lower quadrant pain

Answer 11

Colitis
Diverticulitis
IBD
Ectopic pregnancy
Uterine fibroids
Ovarian torsion
Kidney stones
Pyelonephritis

Question 12

Layers of peritoneum
Space between them

Answer 12

1. Visceral peritoneum covers the abdominal viscera.
2. Parietal peritoneum covers the walls of the abdominoplevic cavity

Space = peritoneal cavity

Can be divided into the greater and lesser sacs

Question 13

What is the parietal peritoneum made of?

Answer 13

Single layer of mesothelium

Question 14

What is mesentery?

Answer 14

Suspends intra-peritoneal organs from the posterior abdominal wall
Double layer of the mesentery

Question 15

What is the parietal peritoneum innervated by? What does this mean?

Answer 15

 innervated by somatic and visceral afferent nerves
 receives sensitive branches from the lower intercostal and upper lumbar nerves (T6-L3).

Sensation, including pain, pressure and temperature is well localised

Question 16

What is the visceral peritoneum innervated by?

Answer 16

Shares the same autonomic innveration as the viscera it surrounds
It is sensitive to stretch and chemical irritation only, which is poorly localised

Visceral peritoneum itself is not innervated, but the sub-mesothelial tissue is innervated by autonomous nerve system:

 sympathetic (T6-L3) and
 parasympathetic (S1-S3) and fibers from the Vagus

Question 17

What parts of the mesentery have specific names?

Answer 17

• Transverse mesocolon – suspends the transverse colon from the posterior abdominal wall.

• Sigmoid mesocolon – located within the left iliac fossa, suspending the sigmoid colon from the posterior
abdominal wall.

• Meso-appendix – a tiny piece of mesentery attaching the appendix to the posterior abdominal wall.

Question 18

Where may the abdominal cavity extend to superiorly?

Answer 18

Up to the 4th intercostal space

Question 19

What can the peritoneal cavity be divided into? What can these be further divided into?

Answer 19

Greater sac – the main part of the peritoneal cavity, which surrounds much of the abdominal viscera. May be further divided into
• Supracolic compartment: located superior to the transverse mesocolon and contains the stomach, spleen
and liver.
• Infracolic compartment: located inferior to the transverse mesocolon and contains the small bowel loops,
ascending and descending colon.

Lesser sac – located behind the stomach and opens into the greater sac via the epiploic foramen (foramen of Winslow).

Lesser sac relatively empty and between the stomach and the liver

Question 20

What joins the greater and lesser sacs?

Answer 20

epiploic foramen (foramen of Winslow).

Question 21

Discuss lesser sac in surgery

Answer 21

In healthy individuals, the lesser sac is usually empty and collapsed. Collections of fluid within the sac may be as a result of infection, ascites, pancreatitis, haemorrhage or bile leak. It is therefore critical that sur- geons explore the lesser sac when undertaking exploratory laparoscopic operations. An abdominal can- not be declared free of disease unless the lesser sac has been fully explored. Additionally, the location of the portal triad within the free edge of the lesser omentum (forming the anterior border of the epiploic foramen) allows surgeons to ligate the blood supply and biliary tree in procedures such as cholecystec- tomy (gallbladder removal).

Question 22

Discuss peritoneal pouches
Difference between males and females

Answer 22

The reflection of the parietal peritoneum onto the superior surfaces of the pelvic organs (bladder, uterus), creates pouches either side of these organs in which fluid can collect. These are:
• Recto-vesical pouch (males): found between the posterior surface of the upper part of the bladder and theanterior surface of the lower 1/3rd of the rectum.
• Vesicouterine pouch (females): found between the posterior surface of the bladder and the anterior surface of the uterus, descending adjacent to the anterior fornix of the vagina.
• Rectouterine pouch (females): also known as the pouch of Douglas. Located between the posterior surface of the uterus and the anterior surface of the rectum.

Question 23

Describe retroperitoneum
Difference between primary and secondary retroperitoneal organs

Answer 23

Organs that sit behind the parietal, and are therefore not entirely encased by peritoneum, are described as retroperitoneal.

Primary retroperitoneal organs are those that developed and subsequently remained within the retroperitoneum. Secondarily retroperitoneal organs are those that developed initially within the intraperitoneal compartment before retracting back to the posterior abdominal wall and the retroperitoneum before birth. The secondarily retroperitoneal organs are the ascending and descending colon.

Question 24

Discuss gas under diaphragm

Answer 24

Gas contained within the peritoneal cavity is called pneumoperitoneum. This is often caused by serious problems within the abdomen, including perforated bowel (due to conditions such as peptic ulcer disease, bowel obstruction, ischaemia, diverticulitis). It may also be caused by gas injected into the abdomen during operations.

The gas is clearly seen on erect chest X-rays, where it collects under the domes of the diaphragm. Here, the gas collects between the parietal peritoneum of the abdominal wall and the visceral peritoneum covering the surface of the liver.

Question 25

Draw difference between intraperitoneal and retroperitoneal structures

Answer 25

Question 26

Mneumonic to remember retroperitoneal organs

Answer 26

SADPUCKER
Suprarenal
Aorta/IVC
Duodenum (D2 and D3)
Pancreas (except tail)
Ureters
Colon - ascending and descending (secondarily retroperitoneal)
Kidneys
(O)esophagus
Rectum

Question 27

Discuss greater/lesser omentum

Answer 27

A large, fatty fold of peritoneum, called the greater omentum, hangs from the greater curvature of the stomach to cover the anterior abdominal viscera like an apron. The greater omentum inserts into the transverse colon at its distal end. The greater omentum functions to isolate regions of infection and inflammation within the abdomen by wrapping around and sticking to affected areas. The smaller lesser omentum runs from the lesser curvature of the stomach to the inferior edge of the liver. The free edge of the lesser omentum contains the portal triad of vessels: proper hepatic artery, common bile duct and the hepatic portal vein.

Lesser omentum is formed by the hepatogastric ligament and the hepatoduodenal ligament

Lesser omentum stops bleeding of liver

Question 28

Memorable dermatomes of anterior abdominal wall

Answer 28

T6 at xiphoid process

T10 at umbilicus

T12 at pubis