Abdomen - karary.edu.sd

Abdomen

Dr. Ahmed Alsharef Farah

Dr. Ahmed Alsharef Farah 1

• The abdominal cavity is the region locatedbetween the diaphragm and sacralpromontory.

• The abdominal and pelvic cavities are commonlydivided into four quadrants or nine distinctregions.

Abdominal Cavity


Sagittal view of the abdominal cavity.Dr. Ahmed Alsharef Farah 3

• A thin serous membrane liningthe walls of theabdominal cavity.

• This membrane is divided into two layers:

The parietal peritoneum, which lines theabdominal walls.The visceral peritoneum, which covers theorgans.

Peritoneum


Axial view of abdomen with peritoneum.Dr. Ahmed Alsharef Farah 5

• The peritoneum forms a cavity that encloses thefollowing organs of the abdomen:

Liver (except for the bare area), Gallbladder,Spleen, Stomach, Ovaries, and majority ofintestines.


• Structures located posterior to the peritoneum,yet lined by it anteriorly, are considered to be inthe retroperitoneum.

Retroperitoneum


• Include abdominal and pelvic structures, such asthe kidneys, Ureters, Adrenal glands,Pancreas, Duodenum, Aorta, Inferior venacava,Bladder,Uterus, and Prostate gland.

• In addition, the Ascending and Descendingcolon and most of the duodenum are situatedin the retroperitoneum.


Axial, T1-weighted MRI of peritoneal and retroperitoneal structures (separated by dotted line).Dr. Ahmed Alsharef Farah 9

Axial CT of peritoneal and retroperitoneal structures (separated by dotted line).Dr. Ahmed Alsharef Farah 10

• The largest organ of the abdomen, occupying amajor portion of the right hypochondriac andepigastric regions.

• The liver can be divided into lobes according tosurface anatomy or into segments according tovascular supply.

• The four lobes are the:Left,Right, Caudate, andQuadrate.

Liver


Anterior view of liver.Dr. Ahmed Alsharef Farah 12

Posterior view of liver.Dr. Ahmed Alsharef Farah 13

Anterior view of segmentation of liver.Dr. Ahmed Alsharef Farah 14

Axial, T1-weighted MRI of abdomen with lobes of liver.Dr. Ahmed Alsharef Farah 15

Axial CT of abdomen with lobes of liver.Dr. Ahmed Alsharef Farah 16

Axial, T1-weighted MRI of liver with quadrate lobe.Dr. Ahmed Alsharef Farah 17

Axial CT of liver with quadrate lobe.Dr. Ahmed Alsharef Farah 18

• The liver receives nutrient-rich blood fromthe gastrointestinal tract via the portal hepaticsystem.

• The major vessel of this system is the portalvein, which is formed by the union of thesuperior mesenteric and splenic veins,posterior to the neck of the pancreas.

Portal Hepatic System


• It enters the liver at the porta hepatis.• At the porta hepatis, the portal vein branchesinto right and left main portal veins that thenfollow the course of the right and left hepaticarteries.


Anterior view of portal hepatic system.Dr. Ahmed Alsharef Farah 21

CT MIP of portal vein.Dr. Ahmed Alsharef Farah 22

Axial, T1-weighted MRI of liver and portal vein.Dr. Ahmed Alsharef Farah 23

Axial CT of liver and portal vein.Dr. Ahmed Alsharef Farah 24

Axial, T1-weighted MRI of abdomen with portal and splenic veins.Dr. Ahmed Alsharef Farah 25

Coronal MR venogram of portal system.Dr. Ahmed Alsharef Farah 26

• The liver is unusual in that it has a dual bloodsupply, receiving arterial blood (20% - 25%) from thecommon hepatic artery and nutrient-rich venousblood (75% - 80%) from the portal vein.

• The venous drainage of the liver occurs via the threemajor hepatic veins, emptying directly into the IVC,just below the diaphragm.


Axial, T1-weighted MRI of abdomen with celiac trunk and hepatic artery.Dr. Ahmed Alsharef Farah 28

Axial CT of abdomen with celiac trunk and hepatic artery.Dr. Ahmed Alsharef Farah 29

Axial, T1-weighted MRI of abdomen with hepatic veins.Dr. Ahmed Alsharef Farah 30

Axial CT of liver with hepatic veins.Dr. Ahmed Alsharef Farah 31

• The biliary system is composed of thegallbladder and bile ducts (Bothintrahepatic and extrahepatic), which serveto drain the liver of bile and store it until it istransported to the duodenum to aid in digestion.

Gallbladder and biliary system


• Bile, formed within the liver, is collected fortransport to the gallbladder by the intrahepaticbile ducts.

• The intrahepatic ducts merge forming theright and left hepatic ducts.

• The right and left hepatic ducts unite at the portahepatis to form the proximal portion of thecommon hepatic duct (CHD), which marksthe beginning of the extrahepatic biliarysystem.


• The CHD joined the cystic duct to form thecommon bile duct (CBD).

• The CBD pierces the medial wall of the secondpart of the duodenum along with the mainpancreatic duct through the ampulla ofVater.

• The ends of both ducts are surrounded by thecircular muscle fibers of the sphincter of Oddi.


• The hollow pear-shaped gallbladder is locatedin the gallbladder fossa on the anteroinferiorportion of the right lobe of the liver.

• It functions as the reservoir for storing andconcentrating bile before it is transported to theduodenum.

• The gallbladder can be divided into:Fundus,Body, andNeck.


Anterior view of biliary system.Dr. Ahmed Alsharef Farah 36

Gallbladder and biliary system.Dr. Ahmed Alsharef Farah 37

MR cholangiopancreatogram (MRCP) of biliary system.Dr. Ahmed Alsharef Farah 38

Sagittal CT reformat of liver and gallbladder.Dr. Ahmed Alsharef Farah 39

Axial CT of abdomen with CBD.Dr. Ahmed Alsharef Farah 40

• The pancreas is a long, narrow retroperitonealorgan that lies posterior to the stomach andextends transversely at an oblique angle betweenthe duodenum and splenic hilum.

• The pancreas can be divided into the:Head, Uncinate process, Neck, Body, andTail.

Pancreas


• The pancreas has both an endocrine (Insulin,Glucagon) and exocrine (Digestiveenzymes) function.

• The arterial supply of the pancreas comes frombranches of the celiac and superiormesenteric arteries.

• Venous blood drains from the pancreas into theportal vein via the superior mesenteric orsplenic vein.


Anterior view of pancreas and extra-hepatic biliary system.Dr. Ahmed Alsharef Farah 43

Sagittal CT reformat of pancreas and IVC.Dr. Ahmed Alsharef Farah 44

Axial CT of abdomen with head of pancreas and duodenum.Dr. Ahmed Alsharef Farah 45

Axial, T1-weighted MRI of pancreas.Dr. Ahmed Alsharef Farah 46

Axial CT of pancreas and pancreatic duct.Dr. Ahmed Alsharef Farah 47

Coronal CT curved-reformat of pancreatic duct.Dr. Ahmed Alsharef Farah 48

• The spleen is the largest lymph organ in thebody composed of lymphoid tissue.

• It is located posterior to the stomach in the leftupper quadrant of the abdomen, protected bythe ninth through eleventh ribs.

• The spleen receives its arterial blood from thesplenic artery and is drained via the splenicvein.

Spleen


Axial, T1-weighted MRI of spleen.Dr. Ahmed Alsharef Farah 50

Axial CT of abdomen of spleen.Dr. Ahmed Alsharef Farah 51

• The paired adrenal (Suprarenal) glands areretroperitoneal organs located superior to eachkidney.

• They are separated from the superior surface ofthe kidneys by perirenal fat and are enclosed,along with the kidneys, by renal fascia(Gerota’s fascia).

Adrenal glands


• The adrenal glands receive arterial blood fromthe superior, middle, and inferiorsuprarenal arteries.

• The drainage of the right gland is via a shortsuprarenal vein that empties directly into theIVC.

• The left gland is drained by the left suprarenalvein, which empties into the left renal vein.


Anterior view of adrenal glands.Dr. Ahmed Alsharef Farah 54

Coronal, T2-weighted MRI with adrenal glands.Dr. Ahmed Alsharef Farah 55

Axial CT of adrenal glands.Dr. Ahmed Alsharef Farah 56

• The structures of the urinary system includethe:

Kidney (Two).Ureter (Two).Bladder.Urethra.

Urinary System


• The kidneys are retroperitoneal bean-shapedorgans that lie against the posterior abdominalwall on either side of the vertebral column.

• They are located on each side of the spinebetween T12 and L4 and are embedded inperirenal fat.

• The right kidney is usually slightly lower due todisplacement by the liver.


Coronal midsection view of kidney.Dr. Ahmed Alsharef Farah 59

• Each kidney is composed of an outer cortexand an inner medulla.

• The renal cortex comprises the outer one thirdof the renal tissue and contains the functionalsubunit of the kidney, the nephron, and isresponsible for filtration of urine.


• The renal medulla consists of segments calledrenal pyramids and function as the beginningof the collecting system.

• Arising from the renal papilla are the cup-shapedminor calyces.

• Each kidney has 7 to 14 minor calyces thatmerge into 2 or 3 major calyces.


• The major calyces join to form the renalpelvis, which is the largest dilated portion of thecollecting system and is continuous with theureters.

• The medial indentation in the kidney is called thehilum; it allows the renal artery and vein andureters to enter and exit the kidney.


Coronal midsection view of internal structures of kidney.Dr. Ahmed Alsharef Farah 63

Sagittal CT reformat of left kidney.Dr. Ahmed Alsharef Farah 65

Coronal, T1-weighted MRI of kidneys.Dr. Ahmed Alsharef Farah 66

Coronal CT Reformat of kidneys.Dr. Ahmed Alsharef Farah 67

Axial, T1-weighted MRI of kidney.Dr. Ahmed Alsharef Farah 68

Axial CT of kidney.Dr. Ahmed Alsharef Farah 69

• The ureters are paired muscular tubes thattransport urine to the urinary bladder.

• Each ureter originates at the renal pelvis anddescends anteriorly and medially toward thepsoas muscles, just anterior to the transverseprocesses of the lumbar spine.

• The ureters then enter the posterior wall of thebladder at an oblique angle.


Axial CT with ureters.Dr. Ahmed Alsharef Farah 71

3D CT Urogram.Dr. Ahmed Alsharef Farah 72

• The stomach is the dilated portion of thedigestive system that acts as a food reservoir andis responsible for the early stages of digestion.

• The stomach is located under the left dome ofthe diaphragm, with the superior portion joiningthe esophagus at the cardiac orifice (Cardiacsphincter), creating the gastroesophagealjunction.

Stomach


• The stomach has two borders called the lesserand greater curvatures.

• Between the two curvatures is the largest portionof the stomach, termed the body.

• On the superior surface of the body is a roundedsurface called the fundus.

• The inferior portion (Pyloric antrum) emptiesinto the duodenum through the pyloricsphincter.


Stomach. Anterior surface.Dr. Ahmed Alsharef Farah 75

• The arterial blood is supplied by branches of thegastric, splenic, and gastroduodenalarteries.

• Venous drainage corresponds to the arterialsupply.

• The gastric veins usually drain directly into theportal vein or into the superior mesenteric vein.


Coronal CT reformat of stomach.Dr. Ahmed Alsharef Farah 77

Axial CT of stomach.Dr. Ahmed Alsharef Farah 78

Axial, T1-weighted MRI of pyloric antrum and pyloric sphincter.Dr. Ahmed Alsharef Farah 79

Axial CT of stomach with pyloric antrum and pyloric sphincter.Dr. Ahmed Alsharef Farah 80

• The small intestine (Small bowel) is locatedbetween the pylorus and ileocecal valve andconsists of loops of bowel averaging 6 to 7 metersin length.

• It can be subdivided into the:

Duodenum, Jejunum, and Ileum.

Intestines


• The large intestine (Large bowel) almostcompletely frames the small intestine and has alarger diameter and thinner walls than the smallintestine and is approximately 1.5 meters long,starting at the ileocecal junction and ending atthe anus.


• The three main divisions of the large intestine arethe:

Cecum, Colon, andRectum.• The colon is the longest portion of the largeintestine and can be subdivided into four distinctportions:

• Ascending, Transverse, Descending, andSigmoid.


Coronal CT reformat of small bowel.Dr. Ahmed Alsharef Farah 84

Axial CT with third (horizontal) portion of duodenum.Dr. Ahmed Alsharef Farah 85

Coronal CT reformat of small bowel and ileocecal valve.Dr. Ahmed Alsharef Farah 86

Coronal, T2-weighted MRI of cecum.Dr. Ahmed Alsharef Farah 87

Coronal MR colonography.Dr. Ahmed Alsharef Farah 88

Axial CT of hepatic and splenic flexures.Dr. Ahmed Alsharef Farah 89

3DCTof

colon.


• The abdominal wall is formed superiorly by thediaphragm and is inferiorly continuous with thepelvic cavity at the pelvic inlet.

Muscles of the abdominal wall


• Posteriorly, the abdominal wall is formedby:

The five lumbar vertebrae.The twelfth pair of ribs.The upper portion of the pelvis.Quadratus lumborum muscles.Psoas muscles.


Anterior view of psoas and quadratus lumborum muscles.Dr. Ahmed Alsharef Farah 93

Axial, T2-weighted MRI of psoas and quadratus lumborum muscles.Dr. Ahmed Alsharef Farah 94

• Anteriorly, the abdominal wall is formedby:

The lower portion of the thoracic cage.Layers of muscles that include the:

1. Rectus abdominis.2. External oblique.3. Internal oblique.4. Transverses abdominis.


Axial view of the abdominal wall.Dr. Ahmed Alsharef Farah 96

Axial CT of the abdominal wall muscles.Dr. Ahmed Alsharef Farah 97

Coronal CT reformat of psoas muscles.Dr. Ahmed Alsharef Farah 98

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