clinical anatomy of the GI tract W8 Flashcards
oesophagus anatomy features
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)
oesophageal contrictions?
superior - cricoid cartilage, junction with pharynx
middle - crossed by aorta and left main bronchus
inferior - diaphragmatic sphincter
oesophageal histology?
mucosa - stratified squamous, non-keratinizing
submucosa - mucous glands
muscularis externa (circular and longitudinal skeletal muscle)
adventitia - loose connective tissue, no serosa
oesophageal layers on ultrasound?
mucosal interface - hyperechoic
mucosa - hypoechoic
submucosa - hyperechoic
muscularis propria - hypoechoic
adventitia - hyperechoic
hyper = bright
hypo = dark
why can patients with oesophageal tumours get hoarse voice?
left recurrent laryngeal nerve is related to movement of vocal chords. if this nerve is affected by the tumour patient gets hoarse voice.
what structures join to form the portal vein? what do these drain from?
superior mesenteric vein - small bowel and right side of large bowel
inferior mesenteric vein - left side of large bowel. joins splenic vein from spleen.
veins draining stomach and oesophagus?
left gastric vein - lesser curve and fundus of stomach
coronary vein - periesophageal plexus to portal vein
same thing?
what happens to the venous system in liver cirrhosis
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.
when can you have clots in superior mesenteric vein (other than cirrhosis?)
what does this lead to?
inflammation of small bowel eg bowel ischaemia, trauma.
varices in small bowel, blood may bypass area.
treatment of oesophageal and gastric varices?
oesophageal - banding (rediverts blood)
gastric - too large to band. inject thrombotic agent to cause thrombosis
stomach anatomy features?
cardia
fundus
body
pyloric area (antrum, pyloric canal, pylorus)
layers of normal stomach?
mucosa
muscularis mucosa
submucosa
muscularis propria
serosa
stomach histology?
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
vessels of coeliac axis?
branches of coeliac:
-left gastric
-common hepatic
-right gastric
-proper hepatic artery
-right
-left
-middle
-supraduodenal
-gastroduodenal (important)
-splenic
gastroduodenal artery clinical relevance?
supplies first part of duodenum (posterior aspect)
often area where duodenal ulcers develop. gastroduodenal artery can be invaded, causing significant bleeding.
liver anatomy features?
common bile duct goes through head of pancreas, drains in ampullary area (sphincter of oddi)
what causes jaundice
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
patient presentation - tumour in head of pancreas?
painless
jaundice
weight loss
back pain
blood supply of foregut/midgut/hindgut?
foregut = coeliac trunk
midgut = superior mesenteric artery
hindgut = inferior mesenteric artery
abdominal angina pathophysiology, symptoms?
narrowing of superior mesenteric artery -> ischaemia in small bowel
abdominal pain after eating
colon blood supply?
superior mesenteric - caecum, ascending, transverse
(marginal artery in transverse where sup and inf join)
inferior mesenteric - transverse, descending, rectosigmoid
