Abdominal Cavity, Contents And Major Viscera Wk9 Flashcards
What is the abdominal cavity?
- It is by far, the largest anatomical cavity of the body by volume
- Much of it lies under the cover of
- Lower Ribs
- &
- Domes of the Diaphragm
- An appreciable amount of the abdominal cavity projects backwards into the pelvis just in front of the buttocks
- It is continuous with the pelvic cavity, inferiorly
- It is the cavity for:
- The Digestive Tract
- Late Pregnancy (Primarily in the Pelvis)
What are the gross anatomical features of the abdominal cavity?
- Diaphragm (Superior)
- Pelvic Brim (Inferior- Imaginary)
- Anterolateral Abdomino-pelvic Wall (Ant-Lat)
- Posterior Abdominal Wall (Posterior)
What are the points of reference on the abdomen?
• 2 Vertical planes
• One on each side of the midline
• A line joining the mid-clavicular point to the mid-
inguinal point.
• It passes just lateral to the tip of the ninth costal
cartilage - which is palpable as a distinct step along the costal margin
• 2 Horizontal planes
• Based on lines drawn between easily palpable
bony points
• Subcostal plane ◦
• A line drawn joining the lowermost bony point of
the rib cage - usually 10th costal cartilage
• body of the L3 vertebra; the origin of the inferior mesenteric artery and 3rd part of the duodenum lie on this plane
• Trans-tubercular plane ◦
• A line uniting the two tubercles of the iliac crests
• upper border of the L5 vertebra and the
confluence of the common iliac veins (i.e. IVC origin) lie on this plane
What are other points of reference?
- Linea Alba
: Xiphoid process
: Pubic symphysis - The umbilicus
What are tissue layers of the abdominal cavity?
- Skin
- Tissue layers of the walls of the abdomen and pelvis
- Anterolateral wall of the abdomen
- Posterior wall of the abdomen
- Walls of the pelvis
- Transversalis Fascia
- Peritoneum
- A lining that forms the deepest tissue envelope housing viscera of the abdomen & pelvis
- Hence known as the ‘epithelium’
What is peritoneum?
- Also known as the pavement epithelium
- It is a one-cell thick tissue membrane
- It lines the:
- Interior surfaces of all of the abdominal wall
- Except Area of the Coronary Ligament
- This is a small area between the liver and the diaphragm
- Known as the Bare Area of the Liver
- Surfaces of all viscera of abdomen
- Except Bare Area of the Liver
- It is classified histologically as Simple Squamous Epithelium
- It shares its characteristics with other epithelia that line inner walls of the body and its organs (in other regions)
What are two variants of peritoneum?
• Two variants of peritoneum are recognised
• Parietal peritoneum
• Visceral peritoneum
• Despite having separate names, these variants of epithelium are continuations of the same layer of membrane
• It is given two separate names depending on its relative location & functions
• The 2 separate sheets of abdominal epithelium
• Parietal peritoneum
– Lines inner walls of the abdomen,
diaphragm and pelvis
• Visceral peritoneum
– Lines visceral organs of the abdomen
What is each layer of the peritoneum innervated by?
• Parietal peritoneum
– Innervated by sensory division of the somatic nervous system
• Its pain sensations are sharp & localised
• Visceral peritoneum
– Innervated by the sensory division of the autonomic nervous system
• Its pain sensations are not ‘localised‘ but perceived as ‘non-defined’ discomfort
What is the peritoneal cavity?
- The cavity that is created between parietal and visceral peritoneum is known as the peritoneal cavity
- It is one of the spaces derived from the coelomic cavity of the embryo
- Others being the
- Pleural cavities around the lungs
- &
- Pericardial cavity around the heart.
- The peritoneal cavity is
- The largest fluid-filled cavity in the body
- It secretes approximately 50 mL of fluid per day
- Its fluid acts as a lubricant and has anti-inflammatory properties
What are gross anatomical features of viscera of the abdomen and pelvis?
- Taken together, viscera of the abdomen are deployed anatomically in relation to a cavity created by boundaries of the peritoneum
- Structures are said to be either
- Within the compartment created by boundaries of the peritoneum
- These are Peritoneal organs
- Outside the compartment created by boundaries of the peritoneum
- These are Extraperitoneal Organs
What are peritoneal organs covered with visceral peritoneum called?
Intraperitoneal organs
What are sub-classifications of extra-peritoneal organs?
- Lying in front of the peritoneal sac
- Pre-peritoneal structures (conceptual)
- Exists only conceptually
- Normally, no structure is found in this area
- This space can be invaded pathologically at the level of the pelvis
- Lying behind the peritoneal sac
- Post-or Retro-peritoneal structures
- The term ‘Post-peritoneal’ is not much used
Peritoneal relationship to peritoneal sac
Covered on all sides or substantially by visceral peritoneum
Intraperitoneal relationship to peritoneal sac
Typical clinical usage: term refers to the abdominal viscera that appear to be ‘inside’ the peritoneal cavity when sac is opened
Extraperitoneal relationship to peritoneal sac
Outside the peritoneal sac
Retroperitoneal relationship to peritoneal sac
Behind the peritoneal sac or not surrounded substantially by peritoneum
What is the gross anatomy of retroperitoneal organs?
- Some visceral organs of the abdomen thus lie outside of the cover of the parietal peritoneum
- These organs are found lying in relation to the posterior abdominal wall
- In these cases the peritoneum will only line one side of such organs
- Such organs are thus referred to as retroperitoneal organs
- These include kidneys & Great Vessels
What does it mean for kidneys to be retroperitoneal structures?
- Kidneys are located within the abdomen
- They are attached to the posterior abdominal wall
- They lie posteriorly to the posterior surface of the parietal peritoneum
- Only their anterior surfaces enjoy covering of the parietal peritoneum
- They are thus, said to be retropritoneal structures
How to remember which abdominopelvic organs are retroperitoneal?
SAD PUCKER
S = Suprarenal (adrenal) glands
A = Aorta/inferior vena cava
D = duodenum (second and third segments)
P = Pancreas U = Ureters (Proximal 50%) C = Colon (ascending and descending only) K = Kidneys ER = Oesophagus
What is the gross anatomy of the abdominal cavity peritoneum?
• The abdominal cavity and its viscera are lined with 2 sheets of epithelium
• Parietal peritoneum
– It lines the internal surface of the abdominal wall
– It blends with visceral peritoneum where these meet
• Visceral peritoneum
– Lines visceral organs as a single continuous sheet of epithelium
• Visceral peritoneum will reflect (i.e. jump or change direction) from one organ to the next as a continuous sheet between adjacent organs
• In some tissues, the epithelium will double back on itself, giving rise to two layers of visceral peritoneum
• The parietal peritoneum does not always cover all surfaces of all organs or walls of abdomen
What is the bare area of the liver?
• It is that part of the liver whose surface is not covered by visceral peritoneum
• When parietal peritoneum of the inferior surface of the diaphragm dives inferiorly to cover the surface of the liver
• In 3D This forms somewhat of a crown over the liver
– This then is known as the coronary ligament
• Some part of the liver ends up without any periotoneal covering
• This is the ‘bare area’ of the liver
• It is important clinically be
What are double folds of visceral peritoneum called?
These double folds can be referred to as either:
– Ligament
– Omentum
– Mesentery
What is a ligament of the abdomen?
– Any double fold of visceral peritoneum that joins any two abdominal organs
– Any double fold of visceral peritoneum that attaches a visceral organ to the posterior abdominal wall
What is an omentum?
– A double fold of peritoneum that starts on the curvatures of the stomach and connects it to other abdominal viscera
– Between the two layers of visceral peritoneum is found fat, peritoneal fluid and white blood cells
What is the greater omentum?
– A double fold of peritoneum that starts on the greater curvature of the stomach and connects it to the transverse colon
– It is also known as the ‘Policeman or Policewoman’ of the abdomen
– Also known as the Abdominal Apron
– It is chemotactic and capable of moving
What is the lesser omentum?
A double fold of peritoneum that starts on the lesser curvatures of the stomach and connects it to the liver
What is a mesentery?
Any double fold of peritoneum starting on the intestines and ending back on the intestines and containing neurovascular structures between the two layers of peritoneum
What are colic compartments?
• The abdomen is divided into
– Supracolic Compartment
– Infracolic Compartment
• The dividing line is determined by the attachments of the transverse mesocolon
What is the supracolic compartment?
• Also known as the: – Sub-diaphragmatic space – Sub-phrenic Space • Divided into 4 sub-spaces as follows: • Coronary Ligament – Left & Right Sub-phrenic spaces • Falciform Ligament divides the space into – Sub-hepatics Spaces • Left Sub-hepatic Space • Right Sub-hepatic Space – Hepatorenal Pouch of Rutherford Morrison
What is the infra-colic compartment?
• It is that part of the Abdominal Cavity that is:
– Inferior to Transverse mesocolon (i.e. mesentery of the transverse colon)
– Superior to The Pelvic Inlet
• Its Visceral Organs Include
– Small intestine
– Ascending
– Descending colon
• Its Anatomical Spaces of Importance are:
– Recto-uterine Pouch (not found in males)
– Recto-Vesical Pouch
What is the coealiac trunk?
• FormedfromBranchesofthe Abdominal Aorta at Vertebral Level L1 From: • leftgastricartery • splenicartery • commonhepatic
What supplies the jejunoileum?
- The superior mesenteric artery supplies the whole small intestine and extends branches up to the middle third of the transverse colon.
- Neuronal innervation is via the vagus nerve (CN X)
What supplies the large intestines?
The inferior mesenteric artery is supplies blood to the left third of the transverse colon and to the sigmoid colon
