Anatomy of Abdomino-Pelvic Cavity (M1 30/10) Flashcards
What is peritoneum?
Peritoneum: a continuous transparent membrane which lines the abdominal cavity and covers the abdominal organs (or viscera).
The visceral and parietal peritoneum are made up of a layer of simple squamous epithelial cells, called mesothelium.
The parietal peritoneum lines the internal surface of the abdominopelvic wall. It is derived from somatic mesoderm in the embryo.
The visceral peritoneum folds to cover the majority of the abdominal organs. It is derived from splanchnic mesoderm in the embryo.
The peritoneal cavity is a space between the parietal and visceral peritoneum. It contains a small amount of lubricating fluid.
What is catheterisation of the bladder?
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Peritoneum Reflections
JUST WATCH THIS:
https://www.youtube.com/watch?v=Uo3jDAXR_Ww
In the Peritoneum reflections have special names:
- Mesentery is double layer of visceral peritoneum between organs and attatches them to the posterior abdominal wall. EG- surrounds the transverse colon (and attatches to the posterior abdominal wall) and small intestine (and attatches to the posterior abdominal wall) .
- Omentum is also a double layer of visceral peritoneum, but between the stomach and other organs (the greater omentum and the lesser omentum).
Intraperitoneal & Retroperitoneal Organs
The abdominal viscera can be divided anatomically by their relationship with the peritoneum. There are two main groups:
Intraperitoneal Organs: are completely covered in visceral peritoneum, anteriorly and posteriorly. Examples include the stomach, liver and spleen. They are suspended by mesentary from the posterior abdominal wall. They get their neurovasculature supply from viscera within mesentaries.
Retroperitoneal Organs: these organs are only covered in peritoneum on their anterior surface. A useful mnemonic to help in recalling which abdominal viscera are retroperitoneal is SAD PUCKER:
S = Suprarenal (adrenal) Glands
A = Aorta/IVC
D =Duodenum (except the duodenal cap- first 2cm)
P = Pancreas (except the tail)
U = Ureters
C = Colon (ascending and descending parts)
K = Kidneys
E = (O)esophagus
R = Rectum
The part of the peitoneal sac that lies behind the stomach and the liver is known as the lesser sac.
Apertures of the Diaphragm
The diaphragm seperates the thoracic cavity from the abdominal cavity, but it has three apertures/ holes:
- Vena Caval Foramen: an orifice in the right lobe of the central tendon of the diaphragm. It allows the vena cava and branches of the right phrenic nerve to pass through. Is the highest of the three and situated at the level of T8.
- Oesophagal Hiatus: is an opening in the diaphragm through which the oesophagus and the vagus nerve pass. Is at the level of T10
- Aortic Hiatus: The opening in the diaphragm through which the aorta and thoracic duct pass. T12
Vena Cava (8 letters) – Passes through the diaphragm at T8.
Oesophagus (10 letters) – Passes through the diaphragm at T10.
Aortic Hiatus (12 letters) – Passes through the diaphragm at T12.
Kidneys
- Lie on the retro-peritoneal wall (sit behind other organs in the abdomen).
- The kidneys are paired retroperitoneal structures (these organs are only covered in peritoneum on their anterior surface). They are normally located between the transverse processes of T12-L3 vertebra. The are on each side of the spinal cord at this level.
- The 12th ribs and the posterier part of the diaphragm lie behind the kidneys.
- The nerves that lie behind/ posterior to the kidneys are the subcostal, iliohypogastic and ilioinguinal.
- What lies in front of the kidneys is different for the right and left kidneys.
- Anteriorly to the right kidney lies the liver (which is the reason why the right kidney is a bit lower than the left) the right colic flexure/ hepatic flexure, the descending part of the duodenum, suprarenal/ adrenal gland.
- Anteriorly to the left kidney lies left colic flexure/ splenic flexure, stomach, spleen, pancreas, suprarenal gland.
- The kidney has three capsules which surround it. Immediately surrounding the kidney, we’ve got the fibrous capsule which adheres to the surface of the kidney. And then we’ve got perinephric fat and then we’ve got the renal fascia.
Ureters
- The ureters are two thick tubes which act to transport urine from the kidney to the bladder. They are 25cm long
- The ureters are funnel-shaped and s-shaped tubes that carry urine from the kidneys
- The ureteric walls are comprised of smooth muscle, which contracts to produce peristaltic waves. This propels the urine towards the bladder.
- The ureters leave the kidney behind/posterior to the renal vessels.
- The urethral sphincters are two muscles used to control the exit of urine in the urinary bladder through the urethra.
- They have a special 1-way valve system that normally prevents urine from flowing back up the ureters in the direction of the kidneys. Vesicoureteral reflux (VUR) is the backward flow of urine from the bladder into the kidneys.
- The upper ureter is supplied by the renal artery and by branches from the gonadal artery (testicular/ ovarian) and aorta.
- The middle ureter is derived from the common iliac and gonadal arteries.
- The distal ureter is supplied by branches of the common iliac and internal iliac branches.
- The ureters have three places where they are very narrow: the pelvic-ureteric junction, the pelvic brim, the ureteric orifice.
Bladder
- Has a capacity of 300ml
- The bladder largely serves two functions:
Temporary store of urine – The bladder is a hollow organ. The walls are very distensible, with a folded internal lining (known as rugae), this allows it to hold up to 600ml.
Assists in the expulsion of urine – During voiding, the musculature of the bladder contracts, and the sphincters relax.
- Please see gray’s anatomy and add to this!
Segments of kidney
Each kidney has 5 segmental branches so can be divided into 5 segments:
Apical: apex/top
Caudal: tail/bottom
Anterior superior (front-middle- but top, but apical on top)
Anterior inferior (front-midddle-but bottom, but caudal below)
Posterior (back- middle- apical on top, caudal below)
Cavities of the human body?
The cavities of the human body can be split into two:
The dorsal cavity: this includes the cranial cavity (skull) and spinal cavity (the spinal cord inside the spine).
The ventral cavity: this includes the thoracic cavity (lungs and heart enclosed by the ribcage) the abdomino-pelvic cavity (the abdominal cavity is all the organs enclosed by the ribcage and pelvis, the pelvic cavity contains bladder, anus, reproductive system).
What is the posterior abdominal wall?
This is the back part of the abdominal cavity, including the organs that are at the back. The organs in the back are: kidneys, suprarenal glands, ureters and bladder. The blood vessells are the aorta and vena cava.
9 region model of abdominal regions is associated with differential diagnosis
Top row:
Right Hypochondriac
Middle: Epigastric
Left hypochondriac
Middle row:
Right lumbar
Umbilical
Left lumbar
Bottom row:
Right Iliac Fossa
Hypogastric
Left Iliac Fossa
What is the retroperitoneal cavity?
Peritoneum is the membrane that lines the abdominal cavity
Outer layer: parietal membrane
Inner layer: visceral membrane
A single layer of flattened mesothelial cells with immune function lie over a connective tissue base
Forms a serous membrane: secretes a lubricating fluid which reduces friction from muscle movement.
Add the practical notes on!!!!
uThe potential space between the parietal and visceral layers is known as the peritoneal cavity.
Muscles of the posterior abdominal wall?
There are five muscles in the posterior abdominal wall:
Quadratus Lumborum
Iliacus
Psoas Major
Psoas Minor
Diaphragm
Blood supply of posterior abdominal wall
The abdominal aorta supplies all the abdominal organs and it begins at T12 and ends at L4, where it divides into the right and left common iliac arteries. All the arteries are divisions of the aorta.
Suprarenal arteries: supply blood to the adrenal glands.
Renal areries: supply blood to the kidneys.
Testicular/ovarian (gonadal) arteries
Lumbar arteries
Right and left common iliac arteries.
Median sacral artery
