Abdomen II Flashcards
Describe the superior mesenteric artery (SMA).
artery of midgut
arise from abdominal aorta L1
runs to the right toward iliac fossa
all branches to the right except jejunal and ileal branches (12-15)
Describe the branches of SMA.
inferior pancreaticoduodenal middle colic right colic ileocolic (appendicular and ileal) ileal-jejunal (12+) marginal artery
Describe the Inferior mesenteric artery (IMA).
artery of hindgut arise from abdominal aorta L3 3 branches runs to the left to Left iliac fossa all branches to the left ends by becoming superior rectal artery (once it crosses the left common iliac artery)
Describe the branches of the IMA.
left colic
sigmoid arteries (2-3)
sup. rectal artery
marginal artery (of drummond)
What are the two arterial anastomoses between GIT arteries?
pancreaticoduodenal marginal artery (artery of drummond)
Describe the pancreas.
gland tissue
retroperitoneal structure
head (uncinate process. within the C) SMA and SMV- anterior to it
neck- portal vein begins
body- splenic artery and vein
tail- splenorenal ligament
Describe the duodenum.
C-shaped (Pancreas is in the C)
is the first part of small intestine (shortest, widest, and fixed)
is a retroperitoneal structure (except 1st part)
extends from pylorus to the duodenojejunal flexure
4 parts
Describe the locations of the 4 parts of the duodenum.
1st- anterolateral to L1 2nd- right to L2-L3 3rd- at L3 4th- Left at L3-L2 muscle of treitz
Describe the four parts of the duodenum.
superior- first part, attachment site for hepatoduodenal ligament of lesser omentum (not retroperitoneal for first 1 or 3 inches) (site of duodenal ulcers)
descending- second part, where bile and pancreatic ducts empty
inferior- third part, crosses inferior vena cava and aorta and is crossed anteriorly by mesenteric vessels
ascending- fourth part, tethered by suspensory ligament at duodenojejunal flexure
Describe the small intestine’s parts.
duodenum
jejunum
ileum
jejunum and ileum are suspended by mesentery
attached -root is 6 inches
free- is 6 meter (loops)
Describe the jejunum and ileum of the small intestine.
begins duodenojejunal flexure
ends at ileocecal junction
jejunal and ileal of SMA anastamose… arcades… vasa recta
Describe the features of the large intestine.
Omental appendices- small pouches filled w fat, absent in CAR (cecum, appendix and rectum)
taeniae coli- outer longitudinal muscle layer thickened to form 3 bands
haustra- between taeniae coli, colon bulges forming 3 rows of pouches
Describe the cecum and appendix.
Appendix behind cecum in 75 percent of us.
What is Meckel’s diverticulum.
Syndrome of 2's 2 feet from IC valve 2 inches long 2 percent of population 2 percent are symptomatic 2 types of ectopic tissue (gastric and pancreatic) 2 years of age at clinical presentation and 2 times more common in boys inflammation of Meckel's diverticulum gives the same picture of acute appendicitis.
What is appendicitis?
an acute inflammation of the appendix due to viral or bacterial infection. Infection of the appendix may result in thrombosis of the appendicular artery (branch of ileocolic artery) which may lead to perforation of the appendix.
What is the portal vein between?
between 2 sets of capillaries
blood collected from intestinal capillary bed passes through the portal vein then through liver sinusoid capillary bed then collects in hepatic veins then reaches IVC
How does the portal vein begin and end?
begins as a VEIN ( near neck of pancreas by union of SMV and splenic vein)
ends as ARTERY (in porta hepatis by dividing into right and left branches) to supply liver with 75 percent of its blood and 50 percent of the required oxygen.
Describe VAD.
Posterior to anterior (portal vein is always Posterior in its course)
portal Vein, hepatic Artery, hepatic Duct
Describe the tributaries of the portal vein.
SMV, splenic vein, IMV, right and left gastric veins, cystic veins, paraumbilical veins
No celiac vein
no gastroduodenal
The portal system has multiple anastomoses with the systemic caval system (IVC and Azygos) which allow for rerouting the venous return to the heart. Which are the most important sites of Portal-caval (systemic) anastomoses?
left gastric vein and esophageal vein of azygos system
superior rectal vein and middle and inferior rectal veins
paraumbilical veins and radicles of the superficial epigastric veins
Liver cirrhosis (progressive liber fibrosis) disrupts the portal blood flow leading to portal hypertension. What can this lead to?
inferior end of esophagus - esophageal varices… hematemesis = vomiting blood
inferior end of rectum - rectal varices… hemorrhoids = bleeding per rectum)
around umbilicus - caput medusae …varicose veins radiating from the umbilicus (Medusa’s head)
Describe the parasympathetic innervation of GIT.
peristalsis/sphincters?
foregut and midgut?
hindgut?
+ peristalsis, -sphincters
foregut and midgut- vagus nerves
hindgut: pelvic splanchnic nerves (parasympathetic sacral outflow S2, 3, 4)
all fibers are preganglionic and will relay in the terminal ganglia of their organs
cranio-sacral
Describe the sympathetic innervation of GIT.
foregut and midgut - thoracic splanchnic nerves. Greater (T5-T9), Lesser (T10-T11), Least (T12)
(presynaptic sympathetic fibers)
hindgut- lumbar splanchnic nerves.
thoracolumbar
