Digestive system: hindgut Flashcards
When does the aorta bifuricate
L4
Name the 3 main branches of the inferior mesenteric artery
the left colic artery (most superior), sigmoidal arteries (multiple), and the superior rectal artery (most inferior)
What does the left colic artery split into
ascending and descending branch
What does the ascending branch of the left colic artery do
ascends to anastomose with the left branch of the middle colic artery, meaning the ascending branch vascularizes part of the descending colon
What does the ascending branch of the left colic artery do after it has vascularized part of the descending colon
Then goes intraperitoneal into the transverse mesocolon and vascularizes the distal third of the transverse colon
Where does the descending branch of the left colic artery go
ascends along the descending colon and sends off branches to supply the descending colon, it anastomoses with the next branch down.
Where do the sigmoidal arteries enter
the sigmoid mesocolon
What do the sigmoidal arteries form
form arcades and vascularize the distal part of the descending colon and the sigmoid colon
What does the superior rectal artery supply
distal part of the sigmoid colon and the proximal rectum
Where does the superior rectal artery run
crosses over the common iliac vessels, and enters the pelvic cavity
Where does the superior rectal artery split
splits into 2 branches (at the level of S3) and descends down the sides of the rectum.
What happens in the large intestine
water and electrolytes are absorbed from the intestinal contents, causing the contents to change from liquid to solid
What does the large intestine consist of
the caecum, appendix, colon, rectum and the anal canal
Where does the cecum hang
hangs downward in the right iliac fossa, lying almost free of peritoneal attachments.
What are the 4 parts of the colon
ascending, transverse, descending and sigmoid colon
How is the longitudinal muscle in the large intestine different to the small intestine
The longitudinal muscle isn’t continuous, it is gathered into 3 stripes called tenia(e) coli.
What are sacculations in the large intestine
The longitudinal muscle is shorter than the length of the colon and have a drawstring effect producing bulging sacculations
What are diverticuli in the large intestine
they are protusions of mucosa through the muscular layer
What is the mucus membrane of the large intestine like
smooth because they have no villi
What covers the ascending colon
peritoneum from the posterior abdominal wall, covers the front and sides
Where does the ascending colon end
at the right colic flexure (hepatic flexure)
Where does the hepatic flexure lie
just below the lowest part of the liver and gall bladder and in front of the lower part of the right kidney.
How does the transverse colon cross the abdominal cavity
from right to left
Where does the transverse mesocolon cross
crosses the head of the pancreas, and the duodenum
What connects the transverse colon to the greater stomach
the gastrocolic ligament
How does the transverse colon end
as the left colic (splenic) flexure
Where does the splenic flexure lie
just below the spleen and in front of the left kidney
Where does the descending colon become the sigmoid colon
a little below the iliac crest
What does the sigmoid colon form
a large freely mobile loop that is attached by the sigmoid mesocolon
Where does the sigmoid colon run
passes down into the pelvic cavity, and approaches the midline
How does the sigmoid mesocolon end
becomes shorter as it enters the pelvis and then ends all together at S3 where it merges with the rectum
Where is the visceral peritoneum on the liver
posteroinferior
Where is the round ligament found
in the falciform ligament
What is the round ligament a remnant of
The fetal umbilical cord
What is ligamentum venosum a remnant of
the ductus venosus of the foetus drainage system
Where is the ligamentum venosum attached to
the left branch of the portal vein within the portal hepatis
Where does the coronary ligament attach
attaches the superior surface of the liver to the inferior surface of the diaphragm and sets the boundaries of the bare surface of the liver
What are the 4 parts of the duodenum
1st part (superior part), 2nd part (descending part), 3rd part (inferior and horizontal part), 4th part (ascending part)
What is the anterior relation to the spleen
stomach
Posterior relation to the spleen
diaphragm (separated it from pleura, lungs and ribs 9-11)
Inferior relation from the spleen
left colic flexure
Medial relation of the spleen
left kidney
Venous drainage of the bowel
There are no veins from the bowel
How much blood does the portal vein bring to the liver
75-80%
How is the portal vein formed
by the splenic vein and superior mesenteric vein uniting
Where is the portal vein formed
posterior to the neck of the pancreas
Where does the inferior mesenteric vein drain
splenic vein but may drain into the junction between the superior mesenteric and splenic veins.
When portal circulation is obstructed how can blood still reach the heart
through IVC by way of anastomoses (no valve - blood can flow in reverse direction)
