W3: Surface markings, peritoneal cavity and peritoneum Flashcards
What is the abdomen proper separated from the pelvis by?
The pelvis inlet
How far may the abdominal cavity extend superiorly?
4th intercostal space
What can the anterior abdomen be divided into?
What do the quadrants contain?
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)
Discuss 9 regions of surface abdo
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.
Discuss quadrants of surface abdo. What are they created by?
Vertical line along the mid-line, passing from diploid to pubic symph, and a horizontal line though the umbilicus
Causes of right upper quadrant pain
Cholecystitis
Cholangitis
Cholelithiasis
Colitis
Diverticulutis
Hepatic absess
Hepatitis
Kidney stones
Pyelonephritis
What is diverticulitis?
Inflammation of pouch of large intestine
Summarise causes of pain in different quadrants
Causes of left upper quadrant pain
Angina
MI
Pericarditis
Oesophagitis
Gastritis
Peptic ulcer disease
Pancreatitis
Pancreatic cancer
Kidney stones
Pyelonephritis
Cause of right lower quadrant pain
Appendicitis
Colitis
Diverticulitis
IBD
Ectopic pregnancy
Uterine fibroids
Ovarian mass
Ovarian torsion
Kidney stones
Pyelonephritis
Causes of left lower quadrant pain
Colitis
Diverticulitis
IBD
Ectopic pregnancy
Uterine fibroids
Ovarian torsion
Kidney stones
Pyelonephritis
Layers of peritoneum
Space between them
- Visceral peritoneum covers the abdominal viscera.
- Parietal peritoneum covers the walls of the abdominoplevic cavity
Space = peritoneal cavity
Can be divided into the greater and lesser sacs
What is the parietal peritoneum made of?
Single layer of mesothelium
What is mesentery?
Suspends intra-peritoneal organs from the posterior abdominal wall
Double layer of the mesentery
What is the parietal peritoneum innervated by? What does this mean?
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
What is the visceral peritoneum innervated by?
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
What parts of the mesentery have specific names?
• 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.
Where may the abdominal cavity extend to superiorly?
Up to the 4th intercostal space
What can the peritoneal cavity be divided into? What can these be further divided into?
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
What joins the greater and lesser sacs?
epiploic foramen (foramen of Winslow).
Discuss lesser sac in surgery
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).
Discuss peritoneal pouches
Difference between males and females
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.
Describe retroperitoneum
Difference between primary and secondary retroperitoneal organs
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.
Discuss gas under diaphragm
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.
Draw difference between intraperitoneal and retroperitoneal structures
Mneumonic to remember retroperitoneal organs
SADPUCKER
Suprarenal
Aorta/IVC
Duodenum (D2 and D3)
Pancreas (except tail)
Ureters
Colon - ascending and descending (secondarily retroperitoneal)
Kidneys
(O)esophagus
Rectum
Discuss greater/lesser omentum
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
Memorable dermatomes of anterior abdominal wall
T6 at xiphoid process
T10 at umbilicus
T12 at pubis
