8 Peritoneal and GI development 1 Flashcards
What is the peritoneum?
Thin serous membrane that lines the walls of the abdominal & pelvic cavities & “clothes” the viscera (organs)
What is the parietal peritoneum?
Lines the walls of the abdominal and pelvic cavities
What is the visceral peritoneum?
Covers the viscera (organs)
What is the peritoneal cavity? What is it divided into?
- Potential space between the parietal and visceral peritoneum
- Divided into greater and lesser sacs
What is peritoneal fluid?
- Small amount of serous fluid that the peritoneum secretes
* Lubricates the surfaces of the peritoneum to allow distension and free movement between the viscera (organs)
What structures do the peritoneum form?
- Omenta (greater and lesser)
- Mesenteries
- Ligaments
What is the difference in the peritoneal cavities of males and females?
Clinical risk?
- In males, the peritoneum is a closed cavity
- In females, there is communication with the exterior through the uterine tubes, the uterus, and the vagina
• Risk - may allow the spread of infection from the exterior to inside the peritoneal cavity
Where is the extraperitoneal tissue (connective tissue) found?
Between the parietal peritoneum and the fascial lining of the abdomen and pelvic walls (transversalis fascia)
What does retroperitoneal mean?
Any structure outside the peritoneal cavity
How is the peritoneal cavity divided?
- Greater sac:
• Main compartment
• Extends from the diaphragm down into the pelvis - Lesser sac (omental bursa):
• Smaller and lies behind the stomach and lesser omentum
• Extends slightly into the greater omentum
What structures allows free communications between the greater and less omentum?
Epiploic foramen of Winslow
What is the function of the epiploic foramen (omental foreamen/ foramen of Winslow)?
The greater and lesser sacs are in free communication via epiploic foramen
What are the triad of vessels in the free border of the lesser omentum?
- Portal vein - posteriorly
- Hepatic artery proper - anteriorly to the left
- Common bile duct - anteriorly to the right
What is the greater omentum?
- Derived from dorsal mesentery
- Attached to greater curvature of stomach and 1st part of duodenum
- Descends like an apron anterior to the small intestine before ascending to the transverses colon
- Consists of a double layer of visceral peritoneum folded upon itself (descending and ascending parts) => 4 layers in total
- Contains fat overlying the transverse colon and much of the small intestine
What structure is the “Policeman of the abdomen”? Function?
- Greater omentum
* Drawn to diseased or perforated structures to seal them off
What is the lesser omentum?
• Derived from the ventral mesentery
• Passes from the lesser curvature of the stomach
& 1st part of duodenum to
the inferior border of the
liver
• It can be subdivided
into the hepatogastric & hepatoduodenal ligaments
What is the hepatoduodenal ligament?
The free edge of the lesser omentum containing the portal vein, hepatic artery proper & common bile duct
What are mesenteries?
- Derived from the dorsal mesentery
- Tissue formed by a double layer of visceral peritoneum
- Suspend the abdominal viscera (organs) from the posterior abdominal wall
- Conduits for blood vessels, nerves & lymphatics
Name the mesenteries in the abdomen
- Small intestine:
• The mesentery
2. Colon: • Ascending • Transverse • Descending • Sigmoid mesocolons
- Vermiform appendix:
• Mesoappendix - Rectum:
• Mesorectum
What is the The Mesentery? Where does base start? Which structures does it cross? How long? Contains branches of which structures?
- A fan shaped double-layered fold of peritoneum connecting the jejunum and ileum to the posterior abdominal wall
- Its base starts at L2 and pass obliquely downwards to just above the right sacroiliac joint
- It crosses the 3rd part of the duodenum, the aorta and IVC, the right gonadal vessels and right ureter
- ~20 cm long
- It contains branches of the SMA and SMV, with nerves and lymphatics
What are the anastomotic arcade differences between the jejunum and ileum?
• The SMA branches are a series of anastomotic arcades within The mesentery
- Jejunum:
• Has few arcades
• Long vasa recta - Ileum:
• Has many arcades
• Short vasa recta
Sigmoid mesocolon:
What is it?
Root?
Transmits which vessels?
- Double-layered fold of peritoneum that connects the sigmoid colon to the posterior abdominal wall.
- Root:
• In the left iliac fossa, crossing the bifurcation of the left common iliac vessels and the left ureter - Transmits:
• The sigmoid branches of the inferior mesenteric vessels plus nerves and lymphatics
As parts of the intestine’s move from being retroperitoneal to intraperitoneal, little folds of peritoneum may be raised or form little recesses such as the ___ recesses
Paraduodenal recesses
Transverse mesocolon:
Function?
Root?
Carries branches?
- Suspends the transverse colon from the posterior abdominal wall
- Root:
• Just inferior to the pancreas - Carries branches of the middle colic vessels
Transverse mesocolon divides the peritoneal cavity (greater sac) into which compartments?
- Supracolic
2. Infracolic