Bleeding in the GI tract and the anatomy of the blood vessels of the abdomen Flashcards
What are the parts of the large intestine in order
caecum appendix ascending colon transverse colon descending colon sigmoid colon rectum anal canal anus
What are the 3 functions of the large intestine
defence
absorption
excretion
Where is the colon in relation to the liver and spleen
Inferior to both the liver and the spleen
What type of organ is the colon
Intraperitoneal, then retroperitoneal then intraperitoneal
Describe the mobility of the intraperitoneal segments of the colon
Quite mobile
How many paracolic gutters do we have?
2 (right and left
Describe the location of the paracolic gutters
Between the lateral eddge of the ascending and descending colon and the abdominal wall
What are the paracolic gutters part of?
The greater sac of the peritoneal cavity
What are the paracolic gutters potential sites for
Pus collection
How many teniae coli do we have and what are they
3
Longitudinal bands of thickened smooth muscle running from caecum to distal end of sigmoid colon
How do we visualise the teniae coli?
Use barium contrast via enema
Where do the appendix and the caecum lie?
Right iliac fossa
What corresponds to the McBurneys point on the anterior abdominal wall
The appendiceal orifice on the posteromedial wall of the caecum
Where is the McBurneys point
A third of the way from the right ASIS to the umbilicus (where pain from appendicitis ends)
WHere does the sigmoid colon lie?
In the left iliac fossa
What gives rise to the movement of the sigmoid and what is the specific name for this?
Long mesentery - sigmoid mesocolon
What is the negative side to the degree of movement of the sigmoid colon?
It can twist around itself and cause a bowel obstruction
What is the risk if a bowel obstruction is not treated?
Infarction
What does the abdominal aorta branch to supply and what are the names of the branches
The abdominal organs
Right and left common iliac arteries
What do the common iliac arteries supply?
The pelvis, perineum and the lower limbs
The common iliac arteries bifurcate again to form what?
The external and internal iliac arteries
Where does the abdominal aorta lie?
Anterior to the vertebral bodies and to the left of the IVC
Name the 3 midline branches of the abdominal aorta
Celiac trunk (foregut)
Superior mesenteric artery (midgut)
Inferior mesenteric artery (hindgut)
What are the names of the 6 parts of the SMA arteries from superior to inferior on the right hand side of the body
Inferior pancreatico-duodenal artery Middle colic artery Right colic artery Ileocolic artery Jejunal and ileal arteries Appendicular artery
What are the names of the 3 parts of the IMA from superior to inferior on the left hand side of the body
Left colic artery
Sigmoid colic artery
superior rectal artery
What can help prevent bowel ischaemia
The marginal artery of Drummond
Why might a patient present with haematemesis
The stomach has filled with blood due to a peptic ulcer in which the wall of the stomach or the duodenum has been eroded through the mucosa
What are varices
Abnormal, dilated veins
Why do varices have the potential to rupture
They have such thin walls
What causes the formation of oesophageal varices?
A result of pathology affecting the portal venous system
How many venous systems does the body have?
Name these
2
Hepatic portal venous system
Systemic venous system
What does the hepatic portal venous system do?
Drains venous blood from absorpitve parts of the GI tract and associated organs to the liver for cleaning
What does the systemic venous system do?
Drains venous blood from all other organs and tissues into the SVC or IVC
What occurs in the liver that requires the hepatic portal system?
First pass metabolism (cleaning)
What does the splenic vein do?
Drains the blood form the foregut structures to the hepatic portal vein
What does the inferior mesenteric vein do?
Drains the blood from the hindgut structures to the splenic vein
What does the superior mesenteric vein do?
Drains the blood from the migut structures to the hepatic portal vein
What are the 3 clinically important sites of venous anastomosis between the systemic and the portal venous systems (Portal systemic anastomeses)
Distal end of oesophagus
Skin around umbilicus
Rectum / anal canal
What means that blood can flow both ways in the anastomoses ?
The presence of small collateral veins
There are no valves in these veins
What would happen to the flow of blood in these collateral veins if the blood pressure within the portal venous system was raised?
Portal Hypertension - blood would be diverted through the collateral veins back to the systemic venous system
As a consequence to portal hypertension, what happens to the collateral veins
THey have amuch larger volume of blood through them than they are used to and so dilate, becoming varicose
What is a clinical sign of portal hypertension
Dilated collateral veins
Dilated epigastric veins
Dilated submucosal collateral veins
Rectal varices
