clinical anatomy of the GI tract W8

Question 1

oesophagus anatomy features

Answer 1

fibromuscular tube C6-T10
innervated by vagus nerve and sympathetic fibres
vagal trunks anteriorly and posteriorly
oesophageal hiatus in diaphragm
right crus of diaphragm forms sphincter-like sling (prevents reflux)

Question 2

oesophageal contrictions?

Answer 2

superior - cricoid cartilage, junction with pharynx

middle - crossed by aorta and left main bronchus

inferior - diaphragmatic sphincter

Question 3

oesophageal histology?

Answer 3

mucosa - stratified squamous, non-keratinizing

submucosa - mucous glands

muscularis externa (circular and longitudinal skeletal muscle)

adventitia - loose connective tissue, no serosa

Question 4

oesophageal layers on ultrasound?

Answer 4

mucosal interface - hyperechoic
mucosa - hypoechoic
submucosa - hyperechoic
muscularis propria - hypoechoic
adventitia - hyperechoic

hyper = bright
hypo = dark

Question 5

why can patients with oesophageal tumours get hoarse voice?

Answer 5

left recurrent laryngeal nerve is related to movement of vocal chords. if this nerve is affected by the tumour patient gets hoarse voice.

Question 6

what structures join to form the portal vein? what do these drain from?

Answer 6

superior mesenteric vein - small bowel and right side of large bowel

inferior mesenteric vein - left side of large bowel. joins splenic vein from spleen.

Question 7

veins draining stomach and oesophagus?

Answer 7

left gastric vein - lesser curve and fundus of stomach
coronary vein - periesophageal plexus to portal vein

same thing?

Question 8

what happens to the venous system in liver cirrhosis

Answer 8

liver becomes nodular, stiff, causing difficulty for blood to get through, portal hypertension.
shunting of blood towards oesophagus (reversal of flow). periesophageal plexus, forms oesophageal varices.
blood drains into hemizygous/azygous system, SVC, systemic circulation.

reversal of flow in splenic vein, collateral circulation forms that joins periesophageal plexus in fundus of stomach, forming gastric varices. reaches systemic circulation.

Question 9

when can you have clots in superior mesenteric vein (other than cirrhosis?)
what does this lead to?

Answer 9

inflammation of small bowel eg bowel ischaemia, trauma.
varices in small bowel, blood may bypass area.

Question 10

treatment of oesophageal and gastric varices?

Answer 10

oesophageal - banding (rediverts blood)
gastric - too large to band. inject thrombotic agent to cause thrombosis

Question 11

stomach anatomy features?

Answer 11

cardia
fundus
body
pyloric area (antrum, pyloric canal, pylorus)

Question 12

layers of normal stomach?

Answer 12

mucosa
muscularis mucosa
submucosa
muscularis propria
serosa

Question 13

stomach histology?

Answer 13

zones - cardiac, fundic, pyloric
glands in all zones have mucous cells and enteroendocrine cells

fundic glands:
-parietal cells
-chief cells
-mucous neck cells
-enteroendocrine cells

Question 14

vessels of coeliac axis?

Answer 14

branches of coeliac:
-left gastric
-common hepatic
-right gastric
-proper hepatic artery
-right
-left
-middle
-supraduodenal
-gastroduodenal (important)
-splenic

Question 15

gastroduodenal artery clinical relevance?

Answer 15

supplies first part of duodenum (posterior aspect)
often area where duodenal ulcers develop. gastroduodenal artery can be invaded, causing significant bleeding.

Question 16

liver anatomy features?

Answer 16

common bile duct goes through head of pancreas, drains in ampullary area (sphincter of oddi)

Question 17

what causes jaundice

Answer 17

gallstones or causes obstruction in bile duct, bile spills over into blood, causes jaundice.

tumour in head of pancreas causes dilation of common duct, enlargement of gallbladder. bile spills over into blood -> jaundice

ampullary tumour -> jaundice

Question 18

patient presentation - tumour in head of pancreas?

Answer 18

painless
jaundice
weight loss
back pain

Question 19

blood supply of foregut/midgut/hindgut?

Answer 19

foregut = coeliac trunk
midgut = superior mesenteric artery
hindgut = inferior mesenteric artery

Question 20

abdominal angina pathophysiology, symptoms?

Answer 20

narrowing of superior mesenteric artery -> ischaemia in small bowel
abdominal pain after eating

Question 21

colon blood supply?

Answer 21

superior mesenteric - caecum, ascending, transverse
(marginal artery in transverse where sup and inf join)
inferior mesenteric - transverse, descending, rectosigmoid