Anatomy 2 Flashcards
What is a mesentary?
Double folded peritoneum which connect individual viscera to the posterior abdominal wall
What is the mesocolon?
It is a mesentary which connect to a component of the large intestine
What is the role of mesentary?
transmit the neurovascular structures from the posterior abdominal wall where they originate to the intraperitoneal viscera which they supply
Make the intraperitoneal structures more mobile
Why do intraperitoneal structures need to be mobile?
We need these structures to be mobile and flexible, for example the stomach needs to be able to expand to accommodate the influx of food, if it were retroperitoneal it would not be able to expand
Where does the nerve supply of the peritoneum come from?
The structure it lines
What is the implication of the peritoneum receiving a nerve supply from the structures it lines?
Thus there is a somatic nerve supply for the parietal peritoneum and a visceral nerve supply to the visceral peritoneum
Describe the progression of pain in appendicitis with regard to the nerve supply of the peritoneum
The appendix is intraperitoneal, thus
when the appendix becomes inflamed and swells the visceral mesentery around it becomes stretched.
It responds to this but the pain associated with it is dull and poorly localised.
It tends to be referred to the umbilical region.
Eventually the tip of the intraperitoneal appendix will impact on the parietal peritoneum. At this point the person will double over and they will be able to very effectively locate the source of the pain. i.e. the pain is being referred through the somatic nerve supply which is sharp, severe and well localised
Same pattern for pleura and pericardium
Is the peritoneal space real or potential?
The intraperitoneal viscera absolutely fill the abdominal cavity.
Thus the peritoneal space is a potential space only.
What is the role of the serous membrane?
The serous membrane is important for providing a friction free glide with the surrounding viscera especially as parts of the digestive system are peristalsing
What is peritoneal dialysis?
Dialysis fluid is put into the peritoneal space so that the fluid and electrolyte exchange can occur across the vast surface area
What is a potential danger associated with the peritoneal space?
It is a disadvantage if there are tumour seeding into the peritoneal space as it allows the rapid spread of tumour along the smooth serous surface
Where are the kidneys located?
On quadratus lumborum in the paravertibral gutters
Where do the ureters travel?
The ureters travel vertically down psoas and along the tips of the lumbar transverse processes
What can be said about unpaired retroperitoneal viscera?
They are secondarily retroperitoneal
What are the unpaired retroperitoneal viscera?
The duodenum, pancreas, bile duct, ascending and descending colon
What sort of mesentary is present during gut tube development?
Dorsal mesentary
Ventral mesentary
What happens to the ventral mesentary?
This will become the falciform ligament
What does it mean to be secondarily retroperitoneal?
All the structures deriving from the GIT initially possess a mesentery.
During development some of these structures lose their mesentery and become retroperitoneal.
These structures are said to be secondarily retroperitoneal.
Where are structures which are secondarily retroperitoneal located relative to those which are truly retroperitoneal?
§ These will lie in front of the structures which are truly retroperitoneal (the kidney, adrenals and ureter)
What happens to the mesentary of the secondarily retroperitoneal organs?
It is resorbed
Where is the stomach located?
Left upper quadrant
What are the subdivisions of the peritoneal cavity?
The greater sac and the lesser sac
What is contained within the greater sac?
The vast majority of the peritoneal cavity
Where is the lesser sac/omental bursa?
It is a space of the peritoneal cavity which is enclosed behind the stomach
What is the purpose of the lesser sac?
§ This is effectively a bursa behind the stomach so it has a nicer bed to expand and contract against. It is serous filled
What is the communication between the lesser and greater sac called?
The epiploic/omental foramen of winslow
What is twisting of the GIT called?
Torsion
Why is the mesentary divided up?
They provide neurovascular inputs to the gut, thus if one were to twist all of the gut would infarct - thus it is divided up into sections
Why do segments of the gut alternate between itnra and retroperitoneal?
It eliminates the possibility of the whole gut infarcting. The retroperitoneal parts provide strength and stability whilst the intraperitoneal parts are mobile (to better facilitate digestion)
What is the root of ‘The Mesentery’?
Where it leaves the posterior abdominal wall
What is ‘The mesentary’
The root of the mesentery attaching the small intestine is called the mesentery
What is the conformation of ‘The mesentary’?
It extends in an oblique line from the DJ flexure above to the ileo-cecal junction below
Crosses the 3rd part of the duodenum and then the aorta and IVC
And then the right psoas as it heads down to the ileo-caecal junction
What is the transverse mesocolon?
The transverse mesocolon is the double folded peritoneum connecting the transverse colon to the posterior abdominal wall
What is the sigmoid mesocolon?
The sigmoid mesocolon is the double folded peritoneum connecting the sigmoid colon to the posterior abdominal wall
Where is the root of the transverse mesocolon?
Across the front of the pancreas and the second part of the duodenum
Where is the root of the sigmoid mesocolon?
It has a small inverted V shaped attachment to the posterior abdominal wall in the left lower quadrant or left iliac fossa
Where does the lesser omentum attach to the stomach?
The lesser curvature
What is the path of the lesser omentum?
Runs via the liver to the abdominal wall, it then surrounds the liver and then goes up to the diaphragm (also considered to be a wall of the abdominal cavity)
It heads towards the visceral surface of the liver in the region of the porta hepatis
It splits to enclose the liver before heading to the top of the cavity and line under surface of the diaphragm.
At the top of the liver it is the coronary and triangular ligaments
The lesser omentum stops at the point where the duodenum becomes retroperitoneal ◊ This is the free edge of the lesser omentum ◊ Behind the free edge of the lesser omentum one reaches the space behind the stomach - the omental bursa
What is the path of the greater omentum?
Coming off the greater curvature of the stomach
Instead of diving back to the peritoneal wall it creates what is called the fatty apron
It comes off the greater curvature and sweeps all the way down to the suprapubic region and then comes back on itself - it gets impregnated with fat
Why is the greater omentum like 4 layers of peritoneum?
2 layers of greater omentum on its way down and then 2 on its way up towards the posterior abdominal wall
How does the greater omentum get to the abdominal wall - which abdominal wall does it go to?
When it goes back to the posterior wall it goes over the top of, and becomes stuck to, the transverse colon
Thus its attachment to the posterior wall is basically the same as the transverse mesocolon
What are the 2 divisions of the lesser omentum?
Hepatogastric
Hepatoduodenal
Where is the Hepatogastric part of the lesser omentum?
○ The part of the lesser omentum going from the stomach to the liver
Where is the Hepatoduodenal part of the lesser omentum?
The part of the lesser omentum gong from the duodenum to the liver
which parts of the greater curvature give rise to the fatty apron?
It is only the distal part of the first curvature and the first inch of the duodenum
What happens to the section of greater omentum that does not form the fatty apron?
The most superior part goes straight to the diaphragm (i.e. to the left dome)
This is called the gastro-phrenic ligament
The middle part of the stomach makes an impression on the visceral surface of the spleen
The greater omentum splits to enclose the spleen before heading back onto the posterior abdominal wall
Called the gastro-splenic ligament/gastro-lienal ligament