Arteries and Nerves of the GI System Flashcards
where does the abdominal aorta begin and end?
T12
L4
where does the abdominal aorta enter the abdomen?
- aortic hiatus
- formed by the left and right crus of diaphragm
what does the abdominal aorta?
-L and R common iliac As.
where does the thoracic duct drain?
into the L subclavian V.
from the abdominal aorta, arteries supplying GI structures…
branch anteriorly and are unpaired
from the abdominal aorta, arteries supplying the non-GI structures…
branch laterally and are paired
abdominal aortic aneurysm
i. Balloon like dilation of the abdominal aorta
ii. Usually arises below the renal arteries and above the aortic bifurcation, so between L1-4
iii. Primarily due to atherosclerosis
iv. Presents as pulsatile abdominal mass that grows with time
v. Aorta should be larger than ~3 cm on palpation
vi. Major complication is rupture when greater than 5 cm
vii. False lumens are sometimes viewed in a CT which is seen as the muscular layer getting filled with blood—before it has ruptured
where does the celiac trunk come off aorta?
T12-L1
what are the 3 main branches of the celiac trunk?
left gastric A
splenic A
common hepatic A
L gastric A
a. gives off esophageal branches
b. will follow lower curvature of the stomach
c. anastomoses with R. gastric A. along the lesser curvature of the stomach
splenic A
a. runs posterior to stomach, superior to pancreas
b. VERY TORTUOUS
c. Within splenorenal ligament
d. Ends as several splenic As.
e. Branches:
i. Short gastric A
ii. Left gastroomental A
iii. Pancreatic branches
short gastric A.
- off of splenic A
1. Upper part of greater curvature
2. Within gastrosplenic ligament
3. Poor anastomoses
left gastroomental A
- off of splenic A
1. Greater curvature of stomach
2. Anastomoses with the R. gastroomental A
pancreatic branches
- off of splenic A
1. Dorsal pancreatic A
2. Inferior pancreatic A
common hepatic A has 2 main branches:
- proper hepatic A.
2. gastroduodenal A.
proper hepatic A
- R. gastric A
a. Anastomoses with L gastric A along the lesser curvature of the stomach - Ends as R and L hepatic A
- cystic A is usually a branch of the R hepatic A
gastroduodenal A
- may give off supraduodenal A
- runs posterior to the duodenum
- bifurcates into R. gastroomental A and superior pancreaticoduodenal A.
a. superior pancreaticosuodenal A bifurcates into Anterior Superior Pancreaticoduodenal A. and Posterior Superior Pancreaticoduodenal A.
what do branches of the celiac trunk supply?
foregut derivatives and spleen
typical arrangement of parts of portal triad
i. Proper hepatic A. (left)
ii. Portal V. (posterior)
iii. Bile duct (right)
iv. Hepatoduodenal L. surrounds it
cholecystectomy
i. Dissection is thru the hepatoduodenal L. to reach the cystic A. which must be ligated before removing the gall bladder
borders of Calot’s triangle
- Common hepatic duct—medially
- Cystic duct—laterally
- Edge of liver—superiorly
- Cystic A—crosses the middle of the triangle
- Calot’s node—main route of lymphatic drainage of gallbladder
superior mesenteric A.
a. 1 cm inferior to the celiac trunk
b. emerges from aorta posterior to the neck of the pancreas
what branch of the celiac trunk supplies the pancreas? what are its branches?
i. superior pancreatoduodenal A
1. A branch of the gastroduodenal
2. Anterior superior pancreaticoduodenal A
3. Posterior superior pancreaticoduodenal A
what is the first branch of the SMA and what are its branches?
- inferior pancreaticoduodenal A
a. Anterior inferior pancreaticoduodenal A.
b. Posterior inferior pancreaticoduodenal A.
what occurs if the abdominal aorta is blocked b/w the celiac trunk and the SMA?
superior pancreaticoduodenal A and inferior pancreaticoduodenal A compensate
what are the branches of the SMA to the small intestine?
- inferior pancreaticoduodenal A
- jejunal A
- ileal A
jejunal A. vs. ileal A.
i. Jejunal A.
1. Long vasa recta and simple arcades
2. Jejunum is well vascularized
a. Tall, close plicae circularis
ii. Ileal A.
1. Complex arcades and short vasa recta
2. Arteries all branch to the left from the superior mesenteric A
3. Ileum is less vascularized
a. Plicae circularis are fewer and shorter or absent
what are the branches of the SMA to the large intestine?
- ileocolic A
- R colic A
- Middle colic A
- marginal A
what are the branches of the ileocolic A?
- Ileal branches
- Colic branches
- Anterior and posterior cecal branches
- Appendicular branch
- Ascending colic branch
what does the R colic A supply?
- To ascending colon
2. To R colic flexure
what does the middle colic A supply?
- Supplies R colic flexure and transverse colon
what does the inferior mesenteric A supply?
derivatives of the hindgut
what are the branches of the inferior mesenteric A?
- left colic A
- sigmoid As
- superior rectal A
- marginal A
ischemic colitis
a. Risk factors
i. Advanced age, clotting abnormalities, hypercholesterolemia, severe hypotension, adhesions, marathons
b. Etiology
i. Atherosclerosis, severe hypotension, blood clot or venous thrombosis, lupus or sickle cell, cocaine
c. Complications
i. Eventual death of tissue which causes bowel perforation and then fecal matter floating throughout the body
where does the superior rectal As and Vs drain?
-inferior mesenteric V
where does the middle rectal As and Vs drain?
-internal iliac V
where does the inferior rectal As and Vs drain?
-internal pudendal V
lymphatics of fate GI system
a. Cisterna Chyle is the origin of the thoracic trunk
i. Intestinal lymphatic trunk and IVC lead to cisterna chyle
sympathetic innervation
- Preganglionic fibers arise at T5-L1—travel in respective splanchnic nerves
a. Synapse in prevertebral sympathetic ganglia - Postganglionic fibers travel from ganglia to abdominal organs
parasympathetic innervation
- Preganglionic fibers travel thru the celiac plexus but DO NOT synapse
a. Synapse on nerve plexi of enteric (intrinsic) nervous system contained in the gut
b. Supplied by vagus and pelvic nerves
enteric nervous system
i. Composed of a series of ganglionic nerve plexi contained within the gut wall
ii. Specialized NS which allows bowel to act independently without you knowing about it
iii. 2 principal components:
1. myenteric (Auerbach’s) plexus
a. between outer longitudinal and inner circular muscle layers
b. motility
2. submucosal (meissner’s) plexus
a. secretions, blood flow, absorption
Hirschsprung Disease
a. Failure of neural crest cells to migrate during intestinal development
b. NO myenteric plexus
i. When you biopsy, you must take some of the muscularis mucosa
1. If you don’t get this up, then you might miss the plexus all together, and would have a misdiagnosis
c. Neural crest cells become the enteric ganglion cells
d. No PS so the gut cannot relax, causing constriction and megacolon of the proximal colon segments
e. Most cases occur in the rectosigmoid junction
f. Down syndrome babies have higher risk
Chagas Disease
a. Abdominal pain, can’t poop
b. Bug bites cheek and poops on you, then you itch it and feces get into bloodstream
c. Parasite (T. cruzi) likes ANS specifically the myenteric plexus
Nerve plexus and artery to the foregut
celiac
PS innervation of foregut
vagus
vertebral level location of foregut
T12-L1
sympathetic innervation levels and nerves of foregut
T5-9
greater splanchnic N
structures of the foregut
stomach, 1st and 2nd part of duodenum, liver, gallbladder, pancreas, spleen
nerve plexus and artery of the midgut
SM
SMA
PS innervation of the the midgut
vagus N
vertebral level location of the midgut
L1
sympathetic innervation levels of the midgut
T10-11
lesser splanchnic N
structures of the midgut
3-4 part of duodenum to 2/3 of transverse colon
nerve plexus and artery of hindgut
IM
IMA
PS innervation of the hindgut
pelvic splanchnic N
vertebral level location of the hindgut
L3
sympathetic innervation of the hindgut
T12-L2
least splanchnic N
structures of the hindgut
-distal 1/3 of transverse colon to upper portion of rectum
