What are the 4 quadrants of the abdomen and which organs are found in what?

RUQ: Right lobe of liver, gallbladder, pancreas head, duodenum, hepatic flexure of colon, small intestine, right kidney with adrenal gland

LUQ: stomach, spleen, body and tail of pancreas, left love of liver, splenic flexure of colon, jejunum, left kidney with adrenal gland

RLQ: large intestines (cecum, appendix, ascending colon), ileum, right ovary

LLQ: large intestinges (sigmoid colon, descending colon), small intestine, left ovary.

*You can also divide the abdomen into 9 quadrants, the R and L hypochondiatic regions, epigastric, R and L lumbar regions, umbilical, R and L inguinal and hypogastric.

What makes up the anterolateral abdominal wall (what are the layers, just like that doctor asked in Selkirk!)

Describe what they generally look like, and their specific origins and insertions. The anterolateral abdominal wall muscles. What nerves innervate them?

External obliques: like hands in your pocket. Origin is lower 8 ribs, inserts on xiphoid, linea alba, pubic sympysis, iliac crest.

Internal obliques: like when you say "insiiiiiide, my feelings are like this..." and you touch your chest with your fingers pointing towards sternum. Origin is the thoracolumbar fascia, illiac crest and inguinal ligament. Instertion is the costal margin and linea alba.

Transversus abdominus: like a belt straight across. Origin is the lower six costal cartilages, thoracolumbar fascia, iliac crest and inguinal ligament. Insertion is xiphoid process, linea alba and pubic crest.

Rectus abdominis: Origin is pubic crest/symphysis. Insertion is the xyphoid process and costal cartilages 5-7.

*Muscles innervated by lower 6 thoracic nerves.

What the difference in how the rectus abdominus is surrounded by it's rectus sheath in the areas above and below midway between the umbilicus and the pubic symphisis?

Above: The rectus sheath is made from the splitting of the aponeurosis of the internal oblique. There they call it the "anterior and posterior lamina".

Below: The rectus sheath is made up of the aponeurosis of the transversalis muscle anterior to the rectus abdominus and then there's just extraperitoneal fascia I think posterior to the muscle. So it's no longer "engulfed" in the internal oblique's aponeurosis, it's sortof now "deeper".

*This stuff goes all the way down until it gets to the arcuate line, which I think is the same as the douglas pouch.

What is the "inguinal canal" and what are its boundaries?

- It's about a 4cm long tube, extending from the deep to the superficial inguinal ring. It's in the anterior abdominal wall, above the medial half of the inguinal ligament. The testes descend through here.

Boundaries:

- Floor: inguinal ligament and medially my lacunar ligament

- Anterior wall: external oblique aponeurosis and by origin of internal oblique muscle.

- Roof: formed by arched inferior fibres of internal oblique and transversus abdominus muscle

- Posterior wall: transversalis fascia (weak fascia) laterally and conjoint tendon medially.

What is the Inguinal (or Hasselbach's) triangle? Why is is special?

- it's a common location for abdominal hernias

Borders:

- Medially: lateral edge of rectus abdominus

- Laterally: inferior epigastric artery and vein

- Inferiorly: inguinal ligament

What's the difference between an indirect and a direct hernia?

Indirect:

- congenital! Most close spontaneously by 1y

- most common type

- more in males than females

- LATERAL to inferior epigastric artery

Direct:

- weakness of transversalis fascia at inguinal (Hesselbach's) triangle

- mostly seen in adults and only in males

- MEDIAL to inferior epigastric artery

Describe the anatomy of the stomach (like the different parts when we look at it from the outside)

Cardia: where the stomach recieves the esophagus. On the left, at the 7th rib anteriorly and T11 posteriorly

Fundus: the top part.

Cardiac notch: angle between esophagus and fundus.

Body: between cardia and pyloric antrum

Pyloric antrum: funnel shapped region between body and pyloric canal

Pyloric canal: contains pyloric sphincter. On the right of midline, at the 9th rib abd L1 posteriorly.

What are the 2 curvatures of the stomach and what attaches to them?

- Greater (more on the bottom and to the left), the greater omentum attaches there

- Lesser, where the lesser omentum attaches.

I recommend reviewing the anatomy zone videos for the peritoneal relations.

- put that on your list.

- describe the greater and lesser sacs, epiploic foramen

What are the boundaries of the epiploic foramen?

*it's the connection between the greater and lesser sacs.

Anterior: free edge of lesser omentum (containing the proper hepatic artery, bile duct and portal vein)

Posterior: peritoneum covering the IVC

Superior: peritoneum of caudate lobe of liver

Inferior: peritoneum of 1st part of duodenum.

*There's a really good picture in GI II (OR GI008 I think it is, the second Marzban one).

Describe the greater and lesser omentums

- greater hangs down like an apron from the greater curvature of the stomach, covers the transverse colon and other abdominal viscera. It's funciton is to adhere to areas of inflammation and wrap around inflamed areas preventing serous diffuse peritonitis. Contains the Gastrophrenic, Gastrosplenic and Gastrocolic ligament.s

- lesser is between the liver and the lesser curvature. From the porta hepatis to the lesser curvature and part of the duodenum. Contains on either side the hepatogastric and hepatoduodenal ligament.

Describe the duodenum

- it's about 25 cm in length and divided into 4 parts

1- Superior: only part that's intraperitoneal, anterolateral to L1. A is liver, P is bile duct and portal v, S is epiloic foramen and I is pancreas

2- Descending: L1-L3, location of major duodenal papilla, entrance of the bile duct and major pancreatic duct (division between foregut and midgut). A is liver and root of transverse mesocolon, P is right kidney, M is pancreas and L is right colic flexure

3- Inferior/Horizontal: crosses L3, superior mesenteric a. and v. cross in front, aortia and IVC behind. S is pancreas, I is coils of jejunum

4- Ascending: L3 to top of L2, terminates at duodenal-jejunal junction, fixed by the suspensory ligament of Treitz to the right crus of the diaphragm. (contraction of the ligament lifts the flexure and widens it's angle, making it easier for contents to move through. A is transverse colon and stomach, P is left renal vessels and inferior mesenteric vein, S is pancreas, I is left kidney

Describe the jejunum (you will later describe the ileum)

- large and closely set of plicae circulares (circular folds).

- less prominent arterial arcades, longer vasa recta, translucent areas (windows) between blood vessels of mesentery.

- upper left abdomen

- 2/5 of the small intest

- wider, thicker, more vascular, redder

- less lymph nodules

- less mesenteric fat

Describe the ileum and how it's different from the jejunum

- small and sparse plicae curculares (circular folds)

- more arterial arcades

- short vasa recta

- no translucent areas (windows) between blood vessels of mesentery

- lower right abdomen

- 3/5 of small intesting

- thinner, narrower, less vascular, palers

-more lymph nodules (known as Peyer's patches)

- more mesenteric fat

What is Meckel's diverticulum?

- one of the common congenital abnormalities (2-4%) of the pop

- happens when the connection between the intestine and the body wall doesnt' completely close off

- small outpouching of the small intestine

- mostly dont' cause any problems, but can become infected cause diverticulitis.

- about 2 feet proximal to ileocaecal valve

What structures are found within the midgut vs. the hindgut? What are 3 distinguishing characteristics of the large intestine?

Midgut: cecum and appendix, ascending colon and 2/3 of transverse colon

Hindgut: 1/3 transverse, descending, sigmoid, rectum, anal canal

1- Teniae coli: 3 separate longitudinal rubbons of smooth muscle along the intestine.

2- Haustra: certain fibres of the teniae coli make it to that it's "sacculated"

3- Appendices epiploicae: the peritoneum sacs of fat attached along the colon.

What is the cecum?

- it's a large blind sac located in the right iliac fossa, above the lateral half of the inguinal ligament.

- S is the ascending colon

- Medially is the cecocolic junction with the iliun (iliocecal junction)

- posteriorly and medially is the appendix. When looking from the inside of the cecum you can see the orifice of the appendix.

Describe the vermiform appendix

- narrow worm like sac arising from the posteromedial wall of the cecum, about 2 cm below the ileocecal orifice (normally about 2 to 20 cm long).

- pain in appendicitis is first felt in the umbilical region. This is reffered pain. *Both the appendix and umbilicus are innervated by segement T10 of the spinal cord. With increasing inflammation, pain is felt in the right iliac fossa. This is caused by involvement of the parietal perioteneaum of the region.

* Parietal peritoneum is sensitive to pain, visceral peritoneum is not.

McBurney's Point

- it's the point of maximum tenderness in appendicitis.

- at the junciton fo the lateral 1/3 and the medial 2/3 of the line joining the umbilicus to the right anterior superior iliac spine and corresponds roughly to the position of the base of the appendix whichc can hang off of the cecum at different angles.

Which parts of the large intestine are retroperoneal? What are the structres A and P to the cecum, Ascending, Transverse and Descending colon?

- The retroperitoneal parts are the ascending and descending. The transverse and sigmoid mesocolons are intraperiotoneal.

- Cecum: A is coils of intestine, P is right psoas and ilacus muscles (situation in the right iliac fossa)

- Ascending colon: A is coils of intestine, P is posterior abdominal wall

- Transverse colon: A is greater omentum, P is duodenum and pancreas.

- Descending colon: A is coils of intestine, P is posterior abdominal wall.

Outline the major differences between small and large intestine.

- Appendices epiploicae: large only

(they are small appendiges of fat wrapped in peritoneum that run along the colon)

- Taeniae coli: large only

(these are the 3 bands of longitudinal smooth musc.)

- Sacculations: large only

- Calibre: smaller in small, larger in large.

- Fixity: greater part is freely mobile in small compared to large which is mostly fixed

- Peyer's patches: present in ileum and absent in large int.

What are the 3 main arteries branching off of the celiac trunk and what do they supply?

Left gastric artery: supplies lesser curvature of the stomach and lower esophagus (esophageal branch)

Splenic artery: gives rise to the short gastric (I think it's the same as the posterior gastric) artery which supplies the fundus. It also gives rise to the left gastroepiploic a. which supplies the left part of the greater curvature of the stomach. That branches off right before it goes into the spleen.

Common hepatic artery: gives 2 things. Gives the right gastric artery which supplies the right side of the lesser curvature of the stomach. It also gives the Gastroduodenal a. Remember it then goes on to become the hepatic artery proper and breaks up into right and left branches before it enters the liver.

* The word gastro-epiploic seems to mean the same thing as gastro-omental, according to the picture.

Take a look at slide 40 of GI 2 and identify the vessels.

How does the duodenum and pancreas get blood supply?

Duodenum: from the celiac trunk and the superior mesenteric arteries

Pancreas: 2 things-

- the superior pancreaticoduodenal a. which is BEFORE the major duodenal papilla - which is where the common bild duct and pancreatic duct perforate the medial side of the second part of the duodenum obliquely.) It comes from the gastroduodenal artery which comes off of the common hepatic artery (from the celiac trunk of course)

- the inferior pancreaticoduodenal a. which is AFTER the major duodenal papilla, and it comes off of the superior mesenteric a.

What the heck is the superior mesenteric artery anyways?

- It comes from the anterior surface of the abdominal aorta just anterior to L1, just below the origin of the celiac trunk, and supplies the intestine from the lower part of the duodenum through 2/3 of the transverse colon, as well as the pancreas.

- it supplies the jejunum and ileum and makes arterial arcades that run within the mesentery of the jejunoileum. The vasa recta (straight arteries) come from the arterial arcades and go to the intestinal wall

*vasa recta always means straight arteries, there are some in the kidney too

- it supplies the cecum through the iliocolic artery

- appendix through the appendicular branches of the iliocolic a.

- ascending colon and proximal 2/3 or the transverse colon, from iliocolic, right and middle colic arteries.

What the flip is the inferior mesenteric artery? What does it supply?

- distal 1/3 of the transverse colon through the left colic artery

- descending colon through the left colic and sigmoid a

- sigmoid colon through the sigmoid artery.

What is the portal vein exactly?

- It's a vein about 8 cm long which collects blood fro the abdominal part of the alimentary tract and accessory organs and then covey it to the liver. It is formed by the union of the superior mesenteric and splenic veins behind the neck of the pancreas. *it looks like the inferior mesenteric vein feeds into the splenic vein before it becomes the portal vein.

- It directly receives these veins:

- left gastric

- right gastric

- superior pancreaticoduodenal

- cystic

- paraumbilical

What are the anastamosing structures present in the portal system which provide important routes of collateral circulation in portal obstructions?

- retroperioneal vein

- paraumbilical vein

- esophageal vein

- rectal vein

Umbilicus: the left branch of the portal v anastamoses with the veins of the anterior abdominal wall (systemic) through the paraumbilical vs. In portal HTN the vs around the umbilicus enlarge forming caput medusa.

Anal canal: the superior rectal vein (portal) anastamoses with the middle and inferior rectal veins (systemic)

Lower end of esophagus: esophageal tributaries of the left gastric vein (portal) anastamose with the esophageal tributaries of the azygous vein (systemic).

What are the 2 major causes he lists of portal HTN?

Nutcracker syndrome

Superior mesenteric artery syndrome

What's the difference in the way that the vasa recta look in the jejunum vs the ileum?

- In the jejunum there are just a few arcades, and the vasa recta are long and few

- In the ileum it looks like there are more arcades, sortof extending towards the intestinal wall inside the omentum so that there the vasa recta coming off of them are shorter and more numerous.