Anatomy- GI bleeds Flashcards
what is the colon made of from proximal to distal
appendix, caecum, ascending colon, transverse colon, descending colon, sigmoid colon
what makes up the large intestine
colon, rectum, anal canal and anus
what are the functions of the large intestsine
defence- commensal bacteria
absorption- H20 and electrolytes
excretion- of formed stool
how mobile is the colon and why
depends on part
transverse and end of descending is intraperitoneal (has own mesentery) so mobile
middle of ascending and descending secondarily retroperitoneal
what are the paracolic
on both sides between lateral edge of ascending and descending colon and abdominal wall- part of greater sac of peritoneal
what is the role of the paracolic gutters
potential sites for pus collection
what lies more superior to splenic ot hepatic flexure
splenic- if not could be splenomegaly
what are haustra
coils in colon formed by tonic contraction of the teniae coli
what is the teniae coli
3 distinct longitudinal bands of thickened smooth muscle running from the caecum to the distal end of the sigmoid colon- combine at the appendix. where contraction occurs
what are where are the omental appendices
small fatty projections- not on small intestine or rectum
what causes the mottling in the rectum on an x ray
faeces
what is used as a contrast in a GI xray and how is it administered
barium via an enema
what quadrant and the caecum and appendix in
right iliac fossa
describe the position of the appendix
variable, most often retrocaecal
what can explain the different presentations of a appendicitis
the variety in appendix position
where is maximum tenderness (in theory) felt in an appendicitis
appendiceal orifice on posterior wall of caecum- 1/3 of the way between right asis to umbilicus
which quadrant is the sigmoid colon in
left iliac fossa
what is the sigmoid mesocolon
mesentery of the sigmoid colon
what is a sigmoid volvulus
when sigmoid mesocolon twists around itself which can result in bowl obstruction and infarction
where is the aorta found
Midline, retroperitoneal structure
Lies anterior to vertebral bodies and to left of IVC
what are the three midline branches of the aorta and what do they supply
Celiac trunk (foregut organs)
Superior mesenteric artery (midgut organs)
Inferior mesenteric artery (hindgut organs)
what do the lateral branches of the aorta supply
Kidneys/adrenal glands Gonads (Testes/Ovaries) Body wall (Posterolateral)
where does the aorta bifurcate into the common iliacs
at L4 (iliac crest)
what does the common iliac bifurcate into
internal and external iliacs
where does the celiac trunk leave aorta
t12
where does the renal artery leave aorta
L1
where does the SMA leave aorta
L1
where does the gonadal artery leave the aorta
L2
where does the IMA leave the aorta
L3
what does the appendicular artery run within
the mesoappendix
describe the jejunum vasculature
longer vasa rectae
larger and fewer arcades
descibe the ileum vasculature
shorter vasa rectae, smaller and many arcades
what does rectus mea
straight
what is the marginal artery of drummond
made of arterial anastomoses between the branches of the SMA and the IMA which help prevent intestinal ischaemia by providing an alternative route by which blood can travel
where does the superior rectal artery come from
IMA
where does the hind gut extend to
the proximal half of the anal canal (pectinate line)
what supplies the distal half of the anal canal
inferior iliac artery (anastomses of hind gut and body wall vasculature)
what are the two main venous systems
hepatic portal (gi to liver for cleaning)
systemic(organs and tissues to IVC)
where is the IVC and what does it do
retroperitoneal
Drains cleaned blood from the hepatic veins into the right atrium
what does the hepatic portal vein
Drains blood from foregut, midgut and hindgut structures to the liver for first pass metabolism
what is the role of the splenic vein
Drains blood form foregut structures to hepatic portal vein
what is the role of the superior mesenteric vein
Drains blood from midgut structures to hepatic portal vein
what is the role of the inferior mesenteric vein
Drains blood from hindgut structures to splenic vein
what is the function of the portal- systemic anastamosis
venous anastomosis between the systemic and the portal venous systems. At these sites, the presence of small collateral veins means blood can flow both ways
- no vlaves
- v little blood in collateral veins
- can go either into systemic/ portal system
where are the portal systemic anastomoses
- skin around umbilicus
- distal end of the oesophagus
- rectum/ anal canal
describe the portal systemic anastomoses at the skin around the umbilicus
connection between para-umbilical veins and small epigastric veins
what system do the epigastric veins drain into
the caval system
what is the caval system
systemic blood flow (vena cava)
where does the inferior part of the distal end of the oesophagus drain into
the hepatic portal vein
where does the superior part of the distal end of the oesophagus drain into
azygous vein
where does the rectum and superior mesenteric vein drain into
superior rectal vein to inferior mesenteric vein
where does the inferior anal canal drain into
the inferior rectal vein to internal iliac veins
where does the middle rectum drain into
middle rectal vein and internal iliac vein
what are the clinical presentations of portal hypertension
oesophageal varices, caput medusae, rectal varices
what is caput medusae
dilated para-umbilical and dilated epigastric veins
give two examples of a cause of haematemesis
peptic ulcer that erodes through the mucosa
bleeding from oesophageal varices
