Abdomen I Flashcards
Peritoneum and its Layers
Serous Membrane which forms the lining of the abdominal cavity
Composed of 2 layers:
PARIETAL
-lines the anterior, posterior, lateral walls of the abdomen. The inferior surface of Diaphragm and the pelvic cavity.
VISCERAL
-leaves the body wall to surround abdominal viscera. It is wrapped around the internal organs that are located inside the intraperitoneal space and is thinner than the parietal peritoneum.
What is between the parietal and visceral layers of the peritoneum?
The peritoneal cavity which is filled with serous fluid, to allow free movement of viscera
Subdivisions of the peritoneal cavity
GREATER SAC
- accounts for most of the space of the peritoneal cavity
- the first place you enter when you open the peritoneum
LESSER SAC
- a small space posterior to the lesser omentum, stomach, liver and inside the greater omentum.
- Continuous to the greater sac via the omental (epiploic) foramen
How do the greater and lesser sac of the peritoneal cavity communicate with each other?
Via the Epiploic foramen (Foramen of Winslow’)
Difference between lesser sac of males and females
Males- closed cavity
Females- The fallopian tube opens through it into the peritoneal cavity
Dorsal mesentery
Double layer of peritoneum
During development the gut tube (Foregut- midgut and hindgut) invaginates into the peritoneal cavity and is suspended from the posterior abdominal wall by this dorsal mesentery.
Names of the peritoneal folds (based on location in GIT):
(a) Stomach- Omentum [lesser and greater]
(b) Small intestine- Mesentery
(c) Large Intestine- Meso-colon [mesoappendix, transverse mesocolon, sigmoid mesocolon]
(d) Abdominal Organs- Ligament [Falciform]
Freely mobile organs
These organs are completely covered by visceral peritoneum so are freely mobile.
- stomach
- 1st part of duodenum
- jejunum
- ileum
- appendix
- transverse colon
- sigmoid colon
- liver
- spleen
Abdominal Viscera
The internal organs enclosed within the abdominal cavity
Retroperitoneal Organs
Organs which develop or come to lie upon the posterior abdominal wall, posterior to the visceral peritoneum.
SAD PUCKER
Suprarenal glands Aorta Duodenum (2nd/3rd parts) Pancreas Ureter Colon Kidney Esophagus Rectum
Ligament
Double layer of peritoneum which connects an organ with another or anterior abdominal wall e.g. Falciform ligament
Mesentery
Double layer of peritoneum which results from the invagination of the peritoneum by the small intestine
Omentum
Double layer of peritoneum passing from the stomach and first part of duodenum to adjacent organs.
- Greater omentum- greater curvature of stomach
- Lesser omentum- lesser curvature of stomach
Nerve supply to the peritoneum
Parietal peritoneum:
- Somatic nerves of the overlying muscles and skin (ex. diaphragmatic peritoneum by phrenic N.)
Visceral peritoneum:
- Autonomic nerves with the underlying viscera
What specific type of innervation does the Visceral peritoneum lack and what type does it have?
It doesn’t have a somatic innervation (it is insensitive to pain) but it receive sympathetic innervation (sensitive to stretch, tension and ischemia).
Blood supply of the 3 parts of the gut tube
(1) Foregut- Celiac trunk (T12)
(2) Midgut- Superior mesenteric artery (L1)
(3) Hindgut- Inferior mesenteric artery (L3)
Commonalities shared by the blood supply of the gut tube
- All 3 arteries are single unpaired branches
- All 3 arteries arise from the anterior surface of the Abdominal Aorta
- All 3 branches anastomose with each other, providing alternative routes of arterial supply
Organs of the Foregut
Stomach Liver Gallbladder Pancreas Spleen 1st half of duodenum
Organs of the Midgut
2nd half of duodenum Jejunum Ileum Cecum Ascending colon Two thirds of transverse colon
Organs of Hindgut
Left one third of transverse colon
Descending colon
Sigmoid colon
Rectum
Branches of the Celiac Trunk
Splenic
Left gastric
Common hepatic
Branches of the Superior Mesenteric Artery
Ileocolic
Right Colic
Middle Colic
Branches of the Inferior Mesenteric
Left Colic
Sigmoid branches
Superior rectal
Favorite number for the stomach
2
Rule of twos of the stomach
- 2 borders with 2 omenta (greater & lesser)
- 2 sacs (greater & lesser)
- 2 surfaces (anterior & posterior)
- 2 ends (cardiac & pyloric)
Divisions of the Stomach
Cardia, Fundus, Body, Pylorus (antrum, canal and sphincter)
Rugae
Mucosa of stomach which is thrown into folds to allow for dilation of the stomach
Blood supply to stomach
Celiac trunk
What separates the structures of the stomach bed, from the stomach?
Lesser Sac
Structures of the stomach bed
Spleen + 4 left and 4 transverse organs
4 LEFT: (left kidney, left suprarenal, left colic flexure, left crus of diaphragm)
4 TRANSVERSE (transverse colon, transverse mesocolon, body of pancreas and splenic artery)
Lesser Omentum
Formed from the ventral mesentery
Double layer of peritoneum extends from the porta hepatis of liver to the lesser curvature of stomach/ 1st part of duodenum.
Main components of Lesser Omentum
Hepatogastric and Hepatoduodenal ligaments
What occurs on the right side of the Lesser Omentum?
On the right side, its two layers become continuous to form the right free margin of lesser omentum, behind which the epiploic foramen is present
Structures at the free border of the Lesser Omentum
Bile duct, hepatic artery and portal vein
Greater Omentum
Formed from the dorsal mesentery.
Double layer of peritoneum which hangs down from the greater curvature of stomach, covering the transverse colon and abdominal viscera.
What does the greater omentum consist of?
Gastro splenic, gastrophrenic, gastrocolic and lienorenal (splenorenal)
Nickname of the Greater Omentum
Policeman of the abdomen. Functions to control infections and protect organs.
What part of the liver is not covered by the Peritoneum?
The “bare area” which lies between the upper and lower layers of coronary ligaments
5 peritoneal fold (ligaments) of liver
4 attached to the diaphragm and abdominal wall by the
- coronary ligament
- falciform ligament
- right triangular ligament
- left triangular ligament
1 attached to the stomach by the:
-lesser omentum
5 surfaces of the liver
- right
- anterior
- posterior
- superior
- inferior (visceral)
5 fissures of the Liver
- Fissure of ligamentum venosum (ductus venosus)
- Fissure for ligamentum teres (round ligament) OBLITERATED UMBILICAL VEINS
- Fossa of gall bladder
- Fissure of IVC
- Porta Hepatis
Porta Hepatis
Lies transversely between the quadrate and caudate lobes.
The structures are arranged in VAD (portal Vein, hepatic Artery, hepatic Duct) from posterior to anterior.
What divides the liver into the right and left anatomical lobe
Falciform ligament, fissure for ligamentum teres and venosum
Divide liver into left lobe and right anatomical lobe (containing caudate and quadrate)
What divides the liver into the right and left function lobes?
Fossa of gallbladder and IVC
This division is based on the blood supply. Divided into right lobe and left functional lobe (contain the caudate and quadrate)
Arterial blood supply of the liver
Blood comes from the hepatic proper artery and portal vein. Each divides into right/left branches.
What is the arterial supply of the caudate and quadrate lobes of the liver?
Left hepatic artery
Left branch of the portal vein
Venous system of the liver
Blood sinusoids to Central Veins to Hepatic Veins to IVC
What is the physiological difference in terms of blood volume and liver oxygen demand between the portal vein and the hepatic artery?
Portal vein: 75% blood and 50% Oxygen demand
Hepatic artery: 25% blood and 50% oxygen demand
Describe the biliary system path
This system is the flow of bile through a series of ducts.
(1) The right and left hepatic ducts come together to form a common hepatic duct.
(2) Bile enters the common hepatic duct via the cystic duct which comes from the gall bladder.
(3) The common hepatic duct transitions into the Common bile duct
(4) The main pancreatic duct (which supplies pancreatic juices) adds into the common bile duct
(5) Bile + Pancreatic juices then flow into the duodenum
From what opening does bile enter the duodenum and which part of the duodenum does it enter
Ampulla of Vater opens on major duodenal papillae at the 2nd part of the duodenum.
Muscle surrounding the lower end of bile duct, pancreatic duct and ampulla which controls the flow of Bile and Pancreatic secretions.
Sphincter of Oddi
3 parts of the Gall Bladder
Fundus, Body, Neck
FUNDUS: Lies at point farthest from the body of neck/cystic duct. This is the site of maximum tenderness in acute gall bladder inflammation.
BODY: The center of the gall bladder. Lies in the “Gall Bladder Fossa” on the inferior surface of the liver.
NECK: Point just before cystic duct. Common site of gall bladder stones.
Hartmann’s pouch
Sac at the posteromedial wall of the neck of the gall bladder. Common site for gall bladder stones.
Basics of the Celiac Trunk
The Artery of the Foregut
The first unpaired branches of the abdominal aorta at level T12 (it is a very short trunk)
It ends by dividing into 3 branches (left gastric, splenic, common hepatic) running in different directions (like Mercedes sign)
Left Gastric Artery
- 1st Branch of Celiac Trunk
- Moves upwards
- Enters lesser omentum
- Supplies branches to the esophagus + stomach
- Ends by astomosing with right gastric artery at lesser curvature of stomach
Splenic Artery
-2nd Branch of Celiac Trunk
- Runs along the superior border of pancreas
- Branches to spleen, pancreas and stomach
- Ends in the lienorenal ligament, giving spleen 5-6 terminal branches
Splenic artery branches to the stomach
- Short gastric arteries
- Left gastroepiploic artery aka gastro-omental
BOTH RUN IN THE GASTROSPLENIC LIGAMENT
How does the left gastroepiploic artery end?
By anastomosing with the right gastroepiploic artery at the greater curvature of stomach
Common Hepatic Artery
- 3rd branch of the celiac trunk
- Branches to the stomach, duodenum and liver.
(1) Gives Gastroduodenal branch
(2) Turn into hepatic artery proper (which gives right gastric)
(3) Gives off right and left hepatic
(4) Ends in Cystic artery branch of Right Hepatic Artery
Where does the Cystic Artery Branch of the Right Hepatic Artery go?
To the Gall Bladder
Branches of the Gastroduodenal artery
- Superior pancreaticduodenal
- Right gastro-omental
Supraduodenal artery
Branch of the common hepatic artery, which may arise from the gastroduodenal or the hepatic artery proper.
What is the spleen?
A large lymphoid organ related functionally to hematopoiesis (formation of blood cell components).
Largest gland the human body
The Liver
Where is the spleen located and how does it connect to the organs near to it?
It is wedged between the stomach and left kidney, connected to them via the gastrosplenic and lienorenal ligaments respectively.
The 2 surfaces of the spleen
DIAPHRAGMATIC: related to the diaphragm, which separates it from the left lung and 9th-11th ribs
VISCERAL: contains the hilum which transmits splenic vessels and gives attachment to gastrosplenic and lienorenal ligaments
Lienorenal ligament
The portion of the greater omentum extending from spleen to diaphragm near the left kidney.
Arterial supply to the Spleen
It is supplied by the celiac trunk which branches to give the SPLENIC ARTERY.
Splenic Artery is very tortuous
Why is splenic artery very tortuous?
In order to accommodate the distention of the stomach.
Venous vessel of the Spleen
Splenic vein.
How does the Splenic Vein go on to help form the portal vein?
It receives the Inferior Mesenteric Vein (IMV) and unites with the Superior Mesenteric Vein (SMV) to give the portal vein.
Where does the portal triad enter?
The foramen of winslow
Another term for the Gastro-omental artery
Gastroepiploic
