Week 1: Overview of the abdomen Flashcards
Describe the major parts of the abdomen
The abdomen is composed of
- abdominal wall
- abdominal cavity
- abdominal viscera
Describe the parts of the abdominal viscera
6 listed
- GI tract and associated organs
- liver
- gallbladder
- pancreas
- spleen
- urinary system (kidney and ureters)
Functions of the muscles of the abdominal wall
- move trunk
- protect viscera
- assist in respiration
- increase intra-abdominal pressure to facilitate micturation, defecation and parturition
What is micturation?
urination
What is defactation?
Bowel movement
What is parturition?
childbirth
What are the muscles of the abdominal wall?
external oblique
internal oblique
transverse abdominus
rectus abdominus
Identify
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Identify and function
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Identify
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What is the linea alba?
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(white line)
is where the aponeuroses from each side interdigitate in the midline between the paired rectus muscles
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Identify
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What is the tendinous intersections?
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are transverse fibrous bands where the rectus sheath attaches to the rectus abdominus muscle
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Identify
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These muscles are often called a ‘six-pack’
Rectus abdominus
Muscles of the abdominal wall from superficial to deep
external oblique
internal oblique
transverse abdominus
The flat muscles end in flat tendons called aponeuroses that form a sheath around the rectus abdominus
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What is the arcuate line?
the arcuate line is where the posterior rectus sheath ends, below it, the rectus abdominus muscle rests on a fascial layer called the transversalis fascia
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Identify
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What is the transversalis fascia?
a fascial layer that the rectus abdominus muscle rests on
The anterior rectus sheath is formed by?
the aponeurosis of the external oblique and part of the aponeurosis of the internal oblique
The posterior rectus sheath is formed by?
the rest of the aponeurosis of the internal oblique and the aponeurosis of the transverse abdominus
The internal oblique aponeurosis contributes to?
both the anterior and posterior rectus sheath
Describe the inferior portion of the posterior rectus sheath
The inferior one-third of the posterior rectus sheath is absent because all three aponeuroses go anterior to the rectus abdominus muscle
Identify
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Describe the innervation of the anterior abdominal wall
anterior or ventral rami of T7-L1 spinal nerves
T7 - T11 abdominal nerves
T7 to T11 are continuations of the intercostal nerves
their accompanying vessels are continuations of the intercostal arteries and veins
T12 abominal nerves
subcostal nerve and vessels
L1 splits into?
iliohypogastric and ilioinguinal nerves
Neurovascular supply to the abdominal wall
- T7-L1 intercostal nerves, arteries and veins
- T12 subcostal nerve, arteries and veins
- L1 iliohypogastric and ilioinguinal nerves
- superior epigastric and musculophrenic arteries (terminal branches of the internal thoracic artery)
- superior and inferior epigastric arteries run posterior to the rectus abdominus within the posterior rectus sheath
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Identify
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Describe the abdominal quadrants and their contents
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Right upper quadrant contents
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Left upper quadrant contents
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Right lower quadrant contents
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Left lower quadrant contents
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epigastric pain region
referred pain from the foregut
Umbilical region pain
referred pain from the midgut
Pubic region pain
referred pain from the hindgut
Structure of the peritoneum
peritoneum is simple squamous (serous) epithelium lining the abdominal cavity and reflecting onto viscera
Location of parietal peritoneum
parietal peritoneum lines the internal surface of the abdominal wall
Visceral peritoneum location
visceral peritoneum covers the viscera
The parietal and visceral peritoneum become continuous at?
the mesentery
Function of the mesentery
provides a path for blood vessels, nerves and lymphatics to reach abdominal organs
Visceral and parietal peritoneum at the mesentery
are continuous
What is the peritoneal cavity?
The peritoneal cavity is a potential space between the parietal and visceral peritoneum that contains only serous peritoneal fluid which allows the organs to move without friction
Does the peritoneal cavity differ among the sexes?
In men, the peritoneal cavity is closed
in women, the uterine tubes open into the peritoneal cavity and thus, is a potential route for spread of infection
What does it mean to be intraperitoneal?
organs covered on all sides by peritoneum
What does it mean to be retroperitoneal?
Organs covered only on one side of peritoneum
Any organ that has a mesentery is?
intraperitoneal
Describe how the peritoneum surrounds organs
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Describe innervation of the parietal peritoneum
parietal peritoneum shares sensory innervation with the abdominal wall from spinal nerves T7-L1
Describe parietal peritoneum and referred pain
sharp, somatic pain localized along the T7-L1 dermatome
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Describe innervation of visceral peritoneum and referred pain
the visceral peritoneum shares innervation with the viscera so pain originating from the abdominal viscera or visceral peritoneum is diffuse, dull referred pain
Pain from the foregut refers to?
epigastric region
Pain from the midgut refers to?
umbilical region
Pain from the hindgut refers to?
pubic or hypogastric region
The peritoneal cavity is divided into?
greater and lesser sac
The greater sac comprises
most of the peritoneal cavity
The lesser sac comprises
a small compartment located posterior to the stomach and inferior to the liver
Lesser Sac AKA
omental bursa
Omental bursa AKA
lesser sac
Communication between the greater and lesser sacs
They communicate via the entrance into the lesser sac called the epiploic foramen of Winslow
Identify greater and lesser sac
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What is a mesentery?
a double layer of peritoneum reflecting from the abdominal wall to enclose viscera
Examples of mesenteries
- Mesenteries of the small intestine (Mesentery proper)
- colic mesenteries (Transverse mesocolon, sigmoid mesocolon)
Mesenteries of the stomach are called?
Omenta
The omenta attaches what to what?
the stomach to other organs and not to the abdominal wall like other mesenteries
What is an omentum?
a double-layer of peritoneum passing from the stomach to another organ
The stomach has how many omenta?
2
the greater omentum
the lesser omentum
Location of the greater omentum
passes from the stomach to the transverse colon and then drapes over it to form an apron in the greater sac
Location of the lesser omentum
passes from the stomach to the liver
the lesser omentum forms the anterior wall of the lesser sac along with the stomach
Where is the epiploic foramen?
posterior to the free edge of the lesser omentum
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Mesenteric ligaments
ligaments are parts of mesenteries between organs or organs and the body wall and are named according to their attachments
Identify and notice the ligaments
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Abdominal spaces and gutters
abdominall or peritoeal spaces and gutters allow the passage of infectious fluids between different compartments of the abdomen and pelvis
peritoneal fluid usually flows upward due to peristalsis (movement) of the intestines
When excess fluid (ascites) accumulates due to pathology, the fluid usually flows downward
Ascites flow can be limited by? the presence of mesenteries and ligaments
Peritoneal fluid flow
- peritoneal fluid usually flows upward due to peristalsis (movement) of the intestines
- When excess fluid (ascites) accumulates due to pathology, the fluid usually flows downward
Greater sac divisions
the transverse mesocolon divides the greater sac into the supracolic and infracolic compartments
Ascites flow limitations
- Ascites flow can be limited by the presence of mesenteries and ligaments
- the transverse mesocolon divides the greater sac into the supracolic and infracolic compartments limiting fluid flow except for laterally
- the phrenicocolic ligament restricts flow on the left
- in the infracolic compartment fluid flows through spaces to the right and left of the colon (paracolic gutters)
Describe peritoneal fluid flow
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Embryological origin of the GI tract
The GI tract can be divided into three regions based on embryological origin
Foregut (celiac trunk)
Midgut (superior mesenteric artery (SMA))
Hindgut (inferior mesenteric artery (IMA))
Parts of the foregut
- esophagus
- stomach
- first half of the duodenum
- liver
- pancreas
- gallbladder
- spleen
Foregut vascular supply
celiac trunk
Parts of the midgut
- 2nd hald of the duodenum
- jejunum
- ileum
- ascending colon
- first 2/3 of the transverse colon
Midgut vascular supply
SMA or superior mesenteric artery
Parts of the hindgut
- last 1/3 of the transverse colon
- descending colon
- sigmoid colon
- rectum
Divisions of the small intestine
Duodenum
Jejunum
Ileum
Divisions of the large intestines
- Ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
Hindgut vascular supply
IMA or Inferior mesenteric artery
Anastomoses and vascular obstruction in the gut
branches of unpaired visceral arteries anastomose at junctions between gut regions and can provide collateral circulation if there is a vascular obstruction
Collateral circulation at the foregut-midgut junction
the superior pancreaticoduodenal artery which is a branch of the celiac trunk anastomoses with the inferior pancreaticoduodenal artery which is a branch of the SMA
Collateral circulation at the midgut-hindgut junction
Near the splenic or right flexure, The middle colic artery from the SMA anastomoses with the left colic artery from the IMA
However, this watershed area is vulnerable to ischemia as the anastomosis is not robust
Anastomoses between the left, middle and right colic arteries form an arterial arch called the marginal artery
The intestinal branches of the SMA do not anastomose with branches of the celiac trunk or IMA rendering the loops of the small intestines susceptible to ischemia
Describe the divisions of the gut and their vascular supply
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some more anastamoses
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Describe gut vascular supply
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Question 1
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- Duodenum
- descending colon
- Kidney
Where are retroperitoneal structures and what are they covered by?
Posterior to the peritoneal cavity and they are covered by peritoneum on their anterior surface and do not have a mesentary
List of retroperitoneal structures
- Esophagus
- 2nd and 4th parts of the duodenum
- Ascending colon
- Descending colon
- rectum
- aorta
- IVC
- Ureters
- Kidneys
- suprarenals
Question 2
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The lesser omentum is made of what parts?
- Hepatoduodenal ligament
- Gastrohepatic ligament
Question 4
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Hepatoduodenal ligament
What is the pringle maneuver?
clamping the hepatoduodenal ligament to control bleeding from the liver
The hepatoduodenal ligament contains …
the portal triad
Question 5
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gastrocolic ligament
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The portal triad consists of what parts?
- Portal vein
- hepatic artery
- Common? bile duct
Question 6
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