Gut Book 2: Abdominal Organization, Peritoneum & Peritoneal Reflections Flashcards
Two methods of surface division
1: nine areas like a tic-tac-toe grid. Mid-clavicular lines passing vertically, horizontal lines : subcostal (passes just inferior to the tenth rib) and transtubercular (passes through the tubercles of the iliac crests)
2: Two perpendicular lines which intersect at the umbilicus that divide the anterior body wall into four quadrants.
Abdominopelvic cavity limits
area enclosed by the muscular and osseous elements which form the abdominal and pelvic walls, between the thoracoabdominal diaphragm above and the pelvic diaphragm below. Formally, the lower limit of the abdominal cavity is the pelvic brim. However, abdominal structures such as the small intestine extend into the area that lies inferior to the pelvic brim, the area referred to as the TRUE PELVIS.
Abdominopelvic cavity: Connective tissue lining (superficial to deep)
Transversalis fascia
Extraperitoneal connective tissue
Peritoneum
Transversalis fascia
lines the entire abdominopelvic cavity, however, does NOT extend into mesenteries which attach viscera to the posterior abdominal wall
Extraperitoneal connective tissue
a loose areolar and fatty layer located between transversalis fascia and parietal peritoneum. This layer also underlies all visceral peritoneum and is, therefore, also referred to as SUBSEROUS FASCIA.
Peritoneum
- a mesothelial layer (simple squamous epithelium of mesodermal origin) which lines the abdominopelvic cavity (PARIETAL) and covers the organs suspended within it and forms all mesenteries (VISCERAL)
- Mesothelium, along with an accompanying layer of submesothelial connective tissue, form a SEROSA which secretes a thin, watery (serous) fluid that reduces friction between opposing peritoneal surfaces.
- The peritoneum is thought of as a closed sac into which the abdominal organs are pushed and suspended. The area within the peritoneal sac is referred to as the PERITONEAL CAVITY and its only normal content is serous fluid.
Why are modalities (pain, pressure, heat, cold) found in skin easily localized to the body wall internally?
The body wall, both externally and internally, is a somatic structure. Parietal peritoneum is supplied by vessels, lymphatics and nerves common to the external body wall and therefore the same modalities found in skin are easily localized to the body wall internally due to its precise spinal innervation.
Rebound tenderness
(pushing on the body wall during palpation in an area of inflammation effectively stretching the parietal peritoneum, letting go abruptly causing increase in pain at the site of palpation) is a result of the precise innervation of the body wall re: parietal peritoneal innervation.
The same modalities are poorly localized to the visceral peritoneum due to the diffuse nature of its autonomic innervation.
Peritonitis
inflammation of the peritoneum, due to air, blood, bacteria, or fecal matter accumulating within the peritoneal cavity from abdominal lacerations, diverticulitis, ruptured appendix, or GI ulcers, results in extreme pain as the visceral and parietal layers appose one another during normal movements (walking, respiration, peristalsis)
What is housed in the abdominal cavity vs. peritoneal cavity?
ABdominal organs are housed in the abdominal cavity; serous fluid is housed in the peritoneal cavity.
Paracentesis
Removal of ascitic fluid is accomplished. Accumulation of excess serous fluid within the peritoneal cavity is referred to as ASCITES. A syringe or trocar inserted at the linea alba superior to the urinary bladder is used to draw off the excess fluid. Depending on the cause of the ascites, liters of fluid can accumulate that need to be removed.
Ascites
Accumulation of excess serous fluid within the peritoneal cavity
Intraperitoneal injections
Due to the large surface area presented by the peritoneum and its absorptive nature, anesthesia and antibiotics can be administered by injecting them into the peritoneal cavity.
Peritoneal lavage
washing the peritoneum with sterile water and antibiotics following abdominal surggeries; used to reduce the occurrence of peritonitis.
Peritoneal dialysis
In patients with renal failure, hypertonic solutions can be injected into the peritoneal cavity and then withdrawn after soluble metabolites have traversed blood vessels into the peritoneal cavity.
Peritoneal adhesions
Peritoneal inflammation, due to infection or endometriosis, can lead to adhesions forming between opposing layers of peritoneum, be it between adjacent layers of visceral peritoneum or between visceral and parietal peritoneum. Either will cause pain or impede the normal movement between organs or between the organs and the body wall. These can be alleviated through adhesiotomy, surgically incising the opposed layers of peritoneum.
Endometriosis
Monthly sloughing of the endometrium, lining of the uterus, does not occur in a one way direction. The uterine tubes are open to the peritoneal cavity. Since the peritoneum provides a nutritive environment, endometrial cells which seed the peritoneal cavity develop into “islands” of endometrial tissue which respond to monthly hormonal changes, thereby effectively “spot welding” coils of intestine to one another as well as to the colon and body wall, resulting in peritoneal adhesions which are painful and may eventually impede the movement of intestinal contents.
Divisions of the peritoneal cavity
Greater and lesser peritoneal sac.
Greater peritoneal sac
includes all areas within the peritoneal cavity except the area housed within the omental bursa.
Mesenteries
duplications of peritoneum which are reflected against one another (two layers) as parietal peritoneum transitions into visceral peritoneum; often referred to as PERITONEAL LIGAMENTS; possess a core of extraperitoneal CT in which vessels, nerves and lymphatics course to and from organs.
What does peritonealized (=intraperitoneal) mean?
Organs covered and suspended by a mesentery are referred to as peritonealized or intraperitoneal.
Organs covered only by peritoneum on one surface are said to be…
retroperitoneal, extraperitoneal or subperitoneal. Retroperitoneal structures are affixed directly to the posterior abdominal wall and are NOT suspended by a mesentery.
Primarily retroperitoneal organs…
originally developed in a retroperitoneal position,i.e. kidney.
Secondarily retroperitoneal organs…
were originally peritonealized, but upon fixation to the posterior body wall during development, became retroperitoneal (duodenum, ascending and descending colon)
Abdominopelvic peritoneal cavity compartments
Supracolic and infracolic, divided tansversely at the level of the transverse colon by the passage of the transverse mesocolon.
Infracolic compartment
peritonealized area directly inferior to the transverse colon and its associated mesocolon.
Houses the small intestine
Subdivisions of the infracolic compartment
Right and left infracolic compartments, divided by the passage of the mesentery proper
Mesentery Proper
dorsal mesentery attaching jejunum and ileum to the posterior abdominal wall along a line from the re-entry point of the duodenum into the peritoneal cavity to the cecum thereby dividing the infracolic compartment into right and left halves.
Right infracolic compartment Boundaries
Superior- transverse colon and its mesocolon
Right- ascending colon
Left- right side of the root of the mesentery
Inferiorly- root of the mesentery and cecum at ileocecal junction
Right infracolic compartment fluid movement
Fluid in this area must first pass to the left infracolic compartment before draining into the pelvic peritoneal cavity.
Left infracolic compartment boundaries
Superior- transverse colon and its mesocolon
Right- left side of the root of the mesentery
Left- descending colon
Inferior- sigmoid colon
Left infracolic compartment: fluid movement
When standing, fluid in this area passes directly into the pelvic peritoneal cavity.
Paracolic Gutters
paired, right and left areas of the infracolic compartment which exist lateral to the ascending and descending colon.
Right paracolic gutter communicates with…
the hepatorenal recess above and the pelvic peritoneal cavity below
The left paracolic gutter connections…
is closed superiorly by the phrenicocolic ligament and opens inferiorly to the pelvic peritoneal cavity.
Paraduodenal folds & fossae
inconstant folds/ elevations of posterior body wall peritoneum at the re-entry point of the duodenum from a retroperitoneal position to the peritonealized proximal jejunum (duodenojejunal flexure): Supraduodenal fold & Fossae Infraduodenal fold & fossae Retroduodenal fossa Paraduodenal fold & fossae
Supraduodenal fold
located above the duodenojejunal flexure; ; houses the supraduodenal fossae posterior to it that is entered from below
Infraduodenal fold
located below duodenojejunal flexure; houses the infraduodenal fossa which is entered from above.
Retroduodenal fossa
peritoneal recess located dorsal to part 4 of the duodenum as it re-peritonealizes
Paraduodenal fold
located to the left of the duodenum, raised by the underlying inferior mesenteric vein; houses the paraduodenal fossa.
Internal (duodenal) hernia
All of the paraduodenal fossae can become confluent leading to the formation of an internal (duodenal) hernia at the duodenojejunal flexure during development. Most are asymptomatic, discovered at autopsy or during dissection. However, they can strangulate necessitating surgical repair. If surgical repair is necessary, care must be taken to spare the inferior mesenteric v. and ascending branch of the left colic a.
Supracolic compartment definition
Peritonealized area between the thoracoabdominal diaphragm and the transverse colon and its associated mesocolon.
Supracolic compartment contents
stomach, spleen, liver, gall bladder, and part one of the duodenum
Subdivision of the supracolic compartment
is done by the lesser omentum thereby forming the omental bursa.
Mesenteries
attachments of the gut to the body wall. There are dorsal and ventral ones.
Dorsal mesenteries
Greater omentum, gastrophrenic ligament, gastrosplenic ligament, phrenicosplenic ligament, splenorenal ligament, phrenicocolic ligament, mesoappendi, transverse mesocolon, sigmoid mesocolon
Greater omentum
a. extension of dorsal mesentery from the greater curvature of the stomach and proximal duodenum.
b. extends anteriorly over the small intestine, loops back to the transverse colon where it fuses with itself to form the gastrocolic ligament
What is housed in the greater omentum?
inferior recess of the lesser peritoneal sac.
Greater omentum clinical correlation
the Greater omentum is highly mobile and can effectively “wall off” areas which are inflamed so as to protect the other abdominal organs from the spread of infection. It also protects the abdominal organs from trauma and insulates the trunk preventing loss of heat.
Gastrophrenic ligament
fundus of stomach to diaphragm
gastrosplenic ligament
greater curvature of stomach to spleen
phrenicosplenic ligament
= sustentaculum lienis- from diaphragm to the left colic flexure; supports the spleen and prevents ascites from entering the supracolic compartment via the left paracolic gutter
mesoappendix
posterior abdominal wall to vermiform appendix
transverse mesocolon
posterior abdominal wall to transverse colon
Sigmoid mesocolon
posterior abdominopelvic area to sigmoid colon
Ventral mesenteries
Lesser omentum, omental bursa (lesser peritoneal sac), falciform ligament, coronary ligaments, triangular ligaments
Lesser omentum
extends from the lesser curvature of the stomach and duodenum to the hilum of the liver (porta hepatis) and, therefore, is divisible into: hepatogastric ligament and hepatoduodenal ligament.
Note: the proper hepatic artery, portal vein and common bile duct travel within the extreme right edge of the hepatoduodenal ligament.
Omental bursa (lesser peritoneal sac)
located posterior to the lesser omentum.
Boundaries: Anterior: hepatoduodeonal ligament Superior: visceral surface of the liver Posterior: IVC and right crus of the diaphragm Inferior: part one of the duodenum
Epiploic foramen (winslow)
entrance to the omental bursa
Falciform ligament
ventral attachment of the liver to the body wall; houses the ligamentum teres hepatitis (obliterated umbilical vein) within its inferior edge.
Peritoneum that envelops the liver in the adult is of what origin?
Recall that the liver devlops within the ventral mesogastrium. Therefore, the peritoneum that envelops the liver in the adult is of ventral origin.
Coronary ligaments
peritoneum which attaches the superior surface of the liver to the abdominal surfaces of the diaphragm (divisible into anterior, posterior, left and right); encircles the superior surface of the liver like a crown; hence coronary. Think: coronation
Triangular ligaments
where anterior and posterior coronary ligaments meet they form right and left triangular ligaments, respectively.
bare area of the liver
identified as an area which is not peritonealized. Since left and right anterior and posterior coronary ligaments meet only laterally relative to the liver forming the triangular ligaments, the area between lies in direct contact with the visceral surface of the diaphragm
Clinical correlation: hepatorenal abscess
When patients with significant purulent ascites are recumbent, fluid in the abdominopelvic peritoneal cavity can drain to the supracolic compartment by passing along the right paracolic gutter to the hepatorenal recess where an hepatorenal/ subphrenic abscess can form. An abscess here can dissect through the vertebrocostal trigone to involve the thoracic cavity.
With repeated turning of the body during sleep, ascitic fluid can enter the omental bursa via the epiploic foramen and disseminate infection to the area behind the stomach (stomach bed).
Fluid from other sources, i.e. accumulations of gastric fluid as a result of a perforated gastric ulcer, can accumulate in the omental bursa.
pancreatic pseudocyst
fluid from an inflamed pancreas can “leak” into the omental bursa resulting in a pancreatic pseudocyst.
