Gut Book 2: Abdominal Organization, Peritoneum & Peritoneal Reflections

Question 1

Two methods of surface division

Answer 1

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.

Question 2

Abdominopelvic cavity limits

Answer 2

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.

Question 3

Abdominopelvic cavity: Connective tissue lining (superficial to deep)

Answer 3

Transversalis fascia
Extraperitoneal connective tissue
Peritoneum

Question 4

Transversalis fascia

Answer 4

lines the entire abdominopelvic cavity, however, does NOT extend into mesenteries which attach viscera to the posterior abdominal wall

Question 5

Extraperitoneal connective tissue

Answer 5

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.

Question 6

Peritoneum

Answer 6

1. 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)
2. 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.
3. 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.

Question 7

Why are modalities (pain, pressure, heat, cold) found in skin easily localized to the body wall internally?

Answer 7

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.

Question 8

Rebound tenderness

Answer 8

(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.

Question 9

Peritonitis

Answer 9

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)

Question 10

What is housed in the abdominal cavity vs. peritoneal cavity?

Answer 10

ABdominal organs are housed in the abdominal cavity; serous fluid is housed in the peritoneal cavity.

Question 11

Paracentesis

Answer 11

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.

Question 12

Ascites

Answer 12

Accumulation of excess serous fluid within the peritoneal cavity

Question 13

Intraperitoneal injections

Answer 13

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.

Question 14

Peritoneal lavage

Answer 14

washing the peritoneum with sterile water and antibiotics following abdominal surggeries; used to reduce the occurrence of peritonitis.

Question 15

Peritoneal dialysis

Answer 15

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.

Question 16

Peritoneal adhesions

Answer 16

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.

Question 17

Endometriosis

Answer 17

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.

Question 18

Divisions of the peritoneal cavity

Answer 18

Greater and lesser peritoneal sac.

Question 19

Greater peritoneal sac

Answer 19

includes all areas within the peritoneal cavity except the area housed within the omental bursa.

Question 20

Mesenteries

Answer 20

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.

Question 21

What does peritonealized (=intraperitoneal) mean?

Answer 21

Organs covered and suspended by a mesentery are referred to as peritonealized or intraperitoneal.

Question 22

Organs covered only by peritoneum on one surface are said to be…

Answer 22

retroperitoneal, extraperitoneal or subperitoneal. Retroperitoneal structures are affixed directly to the posterior abdominal wall and are NOT suspended by a mesentery.

Question 23

Primarily retroperitoneal organs…

Answer 23

originally developed in a retroperitoneal position,i.e. kidney.

Question 24

Secondarily retroperitoneal organs…

Answer 24

were originally peritonealized, but upon fixation to the posterior body wall during development, became retroperitoneal (duodenum, ascending and descending colon)

Question 25

Abdominopelvic peritoneal cavity compartments

Answer 25

Supracolic and infracolic, divided tansversely at the level of the transverse colon by the passage of the transverse mesocolon.

Question 26

Infracolic compartment

Answer 26

peritonealized area directly inferior to the transverse colon and its associated mesocolon.
Houses the small intestine

Question 27

Subdivisions of the infracolic compartment

Answer 27

Right and left infracolic compartments, divided by the passage of the mesentery proper

Question 28

Mesentery Proper

Answer 28

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.

Question 29

Right infracolic compartment Boundaries

Answer 29

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

Question 30

Right infracolic compartment fluid movement

Answer 30

Fluid in this area must first pass to the left infracolic compartment before draining into the pelvic peritoneal cavity.

Question 31

Left infracolic compartment boundaries

Answer 31

Superior- transverse colon and its mesocolon
Right- left side of the root of the mesentery
Left- descending colon
Inferior- sigmoid colon

Question 32

Left infracolic compartment: fluid movement

Answer 32

When standing, fluid in this area passes directly into the pelvic peritoneal cavity.

Question 33

Paracolic Gutters

Answer 33

paired, right and left areas of the infracolic compartment which exist lateral to the ascending and descending colon.

Question 34

Right paracolic gutter communicates with…

Answer 34

the hepatorenal recess above and the pelvic peritoneal cavity below

Question 35

The left paracolic gutter connections…

Answer 35

is closed superiorly by the phrenicocolic ligament and opens inferiorly to the pelvic peritoneal cavity.

Question 36

Paraduodenal folds & fossae

Answer 36

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

Question 37

Supraduodenal fold

Answer 37

located above the duodenojejunal flexure; ; houses the supraduodenal fossae posterior to it that is entered from below

Question 38

Infraduodenal fold

Answer 38

located below duodenojejunal flexure; houses the infraduodenal fossa which is entered from above.

Question 39

Retroduodenal fossa

Answer 39

peritoneal recess located dorsal to part 4 of the duodenum as it re-peritonealizes

Question 40

Paraduodenal fold

Answer 40

located to the left of the duodenum, raised by the underlying inferior mesenteric vein; houses the paraduodenal fossa.

Question 41

Internal (duodenal) hernia

Answer 41

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.

Question 42

Supracolic compartment definition

Answer 42

Peritonealized area between the thoracoabdominal diaphragm and the transverse colon and its associated mesocolon.

Question 43

Supracolic compartment contents

Answer 43

stomach, spleen, liver, gall bladder, and part one of the duodenum

Question 44

Subdivision of the supracolic compartment

Answer 44

is done by the lesser omentum thereby forming the omental bursa.

Question 45

Mesenteries

Answer 45

attachments of the gut to the body wall. There are dorsal and ventral ones.

Question 46

Dorsal mesenteries

Answer 46

Greater omentum, gastrophrenic ligament, gastrosplenic ligament, phrenicosplenic ligament, splenorenal ligament, phrenicocolic ligament, mesoappendi, transverse mesocolon, sigmoid mesocolon

Question 47

Greater omentum

Answer 47

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

Question 48

What is housed in the greater omentum?

Answer 48

inferior recess of the lesser peritoneal sac.

Question 49

Greater omentum clinical correlation

Answer 49

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.

Question 50

Gastrophrenic ligament

Answer 50

fundus of stomach to diaphragm

Question 51

gastrosplenic ligament

Answer 51

greater curvature of stomach to spleen

Question 52

phrenicosplenic ligament

Answer 52

= 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

Question 53

mesoappendix

Answer 53

posterior abdominal wall to vermiform appendix

Question 54

transverse mesocolon

Answer 54

posterior abdominal wall to transverse colon

Question 55

Sigmoid mesocolon

Answer 55

posterior abdominopelvic area to sigmoid colon

Question 56

Ventral mesenteries

Answer 56

Lesser omentum, omental bursa (lesser peritoneal sac), falciform ligament, coronary ligaments, triangular ligaments

Question 57

Lesser omentum

Answer 57

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.

Question 58

Omental bursa (lesser peritoneal sac)

Answer 58

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

Question 59

Epiploic foramen (winslow)

Answer 59

entrance to the omental bursa

Question 60

Falciform ligament

Answer 60

ventral attachment of the liver to the body wall; houses the ligamentum teres hepatitis (obliterated umbilical vein) within its inferior edge.

Question 61

Peritoneum that envelops the liver in the adult is of what origin?

Answer 61

Recall that the liver devlops within the ventral mesogastrium. Therefore, the peritoneum that envelops the liver in the adult is of ventral origin.

Question 62

Coronary ligaments

Answer 62

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

Question 63

Triangular ligaments

Answer 63

where anterior and posterior coronary ligaments meet they form right and left triangular ligaments, respectively.

Question 64

bare area of the liver

Answer 64

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

Question 65

Clinical correlation: hepatorenal abscess

Answer 65

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.

Question 66

pancreatic pseudocyst

Answer 66

fluid from an inflamed pancreas can “leak” into the omental bursa resulting in a pancreatic pseudocyst.