Lecture 17: GI Tract Flashcards
what is peritoneum?
-serous membrane that lines the walls of the abdominal and pelvic cavities, and covers many organs
-forms a sac that encloses the peritoneal cavity
Mesentery
-double fold
-connects parietal and visceral peritoneum
intraperitoneal organ
surrounded by visceral peritoneum
2 main types of peritoneum
-Parietal
-Visceral
Pariteal peritoneum
= of walls
-outer ring
what does the parietal peritoneum line
-inferior surface of diaphragm
-abdominal & pelvic walls
-roof over pelvic viscera
what does the visceral peritoneum cover
organs
2 sacs of peritoneal cavity
greater and lesser
greater sac
diaphragm -> pelvis
lesser sac
-behind the stomach
-can extend:
upward -> diaphragm
downwards -> between ayers of greater omentum
Left -> spleen
right -> Epiploic foramen of winslow
Intraperitoneal
-hanging via messentary
-completely covered by peritoneum
intraperitoneal muscles
liver, stomach, spleen, jejunum, ileum
Retroperitoneal
-behind parietal peritenium in posterior abdominal wall
-anterior surface covered
Retroperitoneal muscles
SAD PUCKER
Suprarenal/adrenal glands
Abdominal Aorta and IVC
Duodenum
Pancreas
Ureters
Colon (ascending & descending)
Kidneys
Esophagus
Rectum
double peritoneal folds
-mesentery
-lesser omentum
-greater omentum
-ligaments
what is in the mesentery
arteries and veins of GI tract
what does the lesser omentum sit between
between liver and lesser curvature of stomach
what acts as an apron over the GI tract
greater omentum
innervation of parietal peritoneum (retroperitoneal)
-segmental nerves: overlying skin & muscles (T6-L1)
-phrenic nerves
-pain is well localized
innervation of visceral peritoneum (intraperitoneal)
-visceral afferents (secondary nerves)
-pain is poorly localized
3 parts of the gut tube
- Foregut
- Midgut
- Hindgut
Foregut
abdominal esophagus to proximal 1/2 of duodenum
-esophagus
-stomach
-liver
-gallbladder
-bile ducts
-pancreas
-proximal duodenum
foregut purpose
digestion
Midgut
distal 1/2 of duodenum to proximal 2/3 of transverse colon
-distal duodenum
-jejunum
-ileum
-cecum
-appendix
-ascending colon
-proximal 2/3 transverse colon
Midgut purpose
absorption (ends digestion)
Hindgut
distal 1/3 of transverse colon to proximal anal canal
-distal 1/3 transverse colon
-descending colon
-sigmoid colon
-upper anal canal
hindgut purpose
removal of waste
blood supply to the foregut
celiac trunk
blood supply to the midgut
superior mesenteric artery
blood supply to the hindgut
inferior mesenteric artery
Branches off the celiac trunk that supply the foregut
-common hepatic artery
-left gastric artery
-splenic artery
branches off the SMA that supply the midgut
-inferior pancreaticoduodenal artery
-jejunal arteries
-Ileal arteries
-middle colic artery
-right colic artery
-Ileocolic artery
no hindgut blood supply to
small intestine
midgut SMA branching
-middle colic artery
-right colic artery
-Ileocolic artery
middle colic artery supplies blood to
superior aspect of transverse colon
right colic artery supplies blood to
ascending colon
midgut structures
-Distal duodenum
-jejunum
-Ileum
-Cecum
-Appendix
-Ascending colon
-Proximal 2/3 trasnverse colon
branches of the IMA in the hindgut
-Left colic artery
-Sigmoidal arteries
-Superior rectal artery
sigmoid arteries supply
sigmoid colon
superior rectal artery supplies
rectum
hindgut structures
-distal 1/3 transverse colon
-descending colon
-sigmoid colon
-upper anal canal
abdominal esophagus
-mechanical digestion and transfer of bolus to the stomach
-passes through diaphragm
where does abdominal esophagus pass through the diagram
-esophagus hiatus
-lower esophageal sphincter
blood supply to diaphragm
esophageal branch of Left Gastric Artery
Rugae
contraction & expansion of the stomach & increases SA for secretion of gastric juices
Blood Supply of greater curvature of the stomach
right & left gastroomental arteries
blood supply to lesser curvature of the stomach
right and left gastric arteries
blood supply to fundus of the stomach
short gastric arteries (via celiac trunk and splenic artery
small intestine
-breaks down proteins, lipids, carbohydrates and absorption by increasing SA
waht does the small intestine extend from
Pyloric orfice -> ileocecal junction
3 parts of the small intestine
duodenum, jejunum, ileum
what does the duodenum attach to proximally
pyloric sphincter of the stomach
how many parts of the duodenum are there
4 parts
-1 is intraperitoneal
-3 are retroperitoneal
duodenum
-20-25cm
-1st part of small intestine
-C-shaped
pancreas relative to duodenum
pancreas punches itself into the C-shape of duodenum
4 parts of the duodenum
-Superior (1st) part)
-Descending (2nd) part
-Inferior/horizontal (3rd) part
-Ascending (4th) part
which part of the duodenum is intraperitoneal
the superior part (level w/ celiac trunk)
2nd (descending) part of duodenum
-retroperitoneal
-contains minor & major papilla
-contains hepatopancreatic Ampulla of Vater
Minor Papilla
bile, gastric juices, and enzymes enter here from pancreas
Major Papilla
drains into descending portion of duodenum
3rd (inferior/horizontal) part of duodenum
-retroperitoneal
-inferior to SMA
-passes anterior to abdominal aorta and IVC
4th (ascending part of duodenum)
-retroperitoneal
-attaches to suspensory ligament of duodenum that hangs the duodenal fissure
-contains duodenojejunal flexure
1st and 2nd part of duodenum is supplied by
anterior & posterior SUPERIOR pancreaticduodenal arteries
3rd and 4th part of duodenum is supplied by
Anterior & posterior INFERIOR pancreaticduodenal arteries
What branches off the SMA to supply the pancreas
- posterior inferior pancreaticduodenal artery
- Anterior inferior pancreaticduodenal artery
Ileum location
-in the right lower quadrant of abdomen
Ileum ends at
the iliocecal junction
Jejunum location
left upper quadrant
Jejunum begins at
the duodenojejunal flexure
where does the 4th portion of the duodenum fold down
duodenojejunal flexure
Mesentery proper
-contains blood supply & VD
-double folding of peritoneum
Jujunum BS
jejunal arteries > arterial arcades > vasa recta
Ileum BS
Ileal arteries > arterial arcades > vasa recta
what do the jujunal arteries and ileal arteries branch off of
SMA
Vasa recta and arcades in the Jejunum
not as many vasa recta & large arcades
vasa recta and arcades in the ileum
more vasa recta and smaller arcades
