Oesophagus, Stomach and Duodenum Part 1 Flashcards
Describe the function of the oesophagus
transports food and fluid to the stomach by peristaltic waves
Describe the position and relations of the oesophagus
- starts in the midline as continuation of pharynx at C6 inferior border of cricoid)
- descends between trachea and vertebral column
- enters thorax behind trachea with arch of aorta to the left in superior mediastinum
- enters abdominal cavity at T10 slightly left of midline
What are the 5 possible constriction of the oesophagus?
4 non-pathological:
- upper oesophageal sphincter C6
- arch of aorta T4
- left main bronchus
- diaphragm T10
1 pathological:
- left atrium if dilated
What is the role of the cricophayngeal sphincter?
prevents air from entering the stomach by the oesophagus
What are the problems with oesophageal constrictions?
- more likely to cause blockage
- can hinder the passage of instruments
- can slow down the passage of damaging substances which can allow them to cause more harm
Describe the neurovascular supply and muscle type of the superior 1/3rd of the oeosphagus
- striated muscle
- arterial: inferior thyroid artery
- venous: BCV
- innervation: vagus (by recurrent laryngeal)
- lymphatic: deep cervical nodes
Describe the neurovascular supply and muscle type of the middle 1/3rd of the oesophagus
- mixed muscle
- arterial: aorta and bronchial arteries
- venous: azygos
- innervation: oesophageal plexus
- lymphatic: tracheobronchial nodes
Describe the neurovascular supply and muscle type of the inferior 1/3rd of the oesophagus
- smooth muscle
- arterial: left gastric and left inferior phrenic arteries
- venous: left gastric and oesophageal vein
- innervation: oesophageal plexus
- lymphatics: left gastric coeliac nodes
What is the abdominal oesophagus?
- shortest part of oesophagus
- from oesophageal hiatus to the cardiac orifice of stomach
- passes through right crus to diaphragm at T10
- tethered to margins of oesophageal hiatus by phrenooesophageal ligament
Describe the neurovascular supply of the abdominal oesophagus
- arterial: left gastric artery (from coeliac trunk)
- venous: portal vein (through left and short gastric veins) and azygos system (through oesophageal veins)
- innervation: oesophageal plexus (parasympathetics from vagus, sympathetics from greater splanchnic)
What are the anti-reflux mechanisms of the lower oesophgeal sphincter?
Major:
- circular smooth muscle fibres in lower oesophagus
- right crus of diaphragm
Minor:
- clasp fibres
- oblique entry of oesophagus into stomach
Achalasia
- when the ganglion cells in the myenteric plexus of the distal oesophagus and gastro-oesophageal junction are reduced or absent
- results in sphincter failing to open during swallowing causing a backup of food
What is the Z-line?
- key landmark used in endoscopy
- where the epithelia between the oesophagus and the stomach changes
- pink stratified squamous epithelia changes to red columnar epithelia
Barrett’s Oesophagus
- pathological replacement of oesophageal squamous epithelium by gastric columnar epithelium
- pre-cancerous as cells are starting to change
Where is the stomach located?
epigastric, left hypogastric and partially umbilical region
What is the Labbe triangle and what are its borders?
- where the stomach is in contact with the abdominal wall
- left costal arch
- lower border of liver
- horizontal line connecting tips of left and right 9CC
What are the functions of the stomach?
- temporary storage of ingested food
- mechanical breakdown of solid food
- chemical digestion of proteins
- mixes food with gastric secretions forming chyme
- regulation of rate of passage of chyme to duodenum
- secretion of acid to aid digestion and absorb iron
- secretion of intrinsic factor for vitamin B12 absorption
- secretion of gut hormones
- microbial defence
What are the anterior relations of the stomach?
- anterior abdo wall
- left costal margin
- diaphragm
- left pleura and lung
- left lobe of liver
What are the posterior relations of the stomach?
- lesser sac
- spleen
- upper pole of left kidney
- left suprarenal gland
- pancreas
- splenic artery
- transverse colon
- transverse mesocolon
Name the arteries that supply the stomach
- all come from the coeliac trunk
- left gastric artery (direct from coeliac trunk)
- right gastric artery (from common hepatic artery)
- left gastroepiploic artery (of splenic artery)
- right gastroepiploic artery (of gastroduodenal branch of common hepatic)
- short gastric arteries (of splenic artery)
Where do the left and right gastric arteries and run and what do they supply?
Left:
- runs along lesser curvature
- supplies abdominal oesophagus, proximal lesser curvature and adjacent body of stomach
Right:
- runs along lesser curvature
- supplies distal lesser curvature and adjacent body of stomach
Where do the left and right gastroepiploic arteries run and what do they supply?
Left:
- runs in gastro-splenic ligament
- supplies the left side of greater curvature and adjacent body of stomach
Right:
- supplies the right side of the greater curvature and adjacent body of the stomach
Where do the short gastric arteries run and what do they supply?
- runs in gastro-splenic ligament
- supplies the fundus of the stomach
Describe the venous drainage of the stomach
- veins run parallel to arteries
- L and R gastric veins to hepatic portal vein
- short gastric and L gastroepiploic veins to splenic vein to hepatic portal vein
- R gastroepiploic vein to superior mesenteric vein to hepatic portal vein
