MEDI7302 Study Guide - Final Guide: Aortic Aneurysm, Antacid, Intubation
Oesophagus
Learning
objectives
Briefly outline the embryology of the foregut, particularly in relation to blood supply
of abdominal foregut structures
Explain the relation between foregut structures and epigastric pain
List symptoms or gastro-oesophageal reflux disease (GORD) including features that
would raise concern
Tabulate a stepwise management plan for GORD, including the role of investigations
Describe the pathology and natural history of Barrett's oesophagus
Contrast the aetiological factors for SCC and adenocarcinoma of the oesophagus
Outline the management options for oesophageal cancer
Understand the pathology of oesophageal achalasia and how it presents
Contrast how dysphagia behaves in the setting of a benign peptic stricture,
achalasia and cancer of the oesophagus
Foregut
embryology
Introduction
Anterior component of the alimentary canal running from mouth -> major
duodenal papilla (D2 of duodenum)
It arises from endoderm developing from the folding primitive gut &
developmentally distinct from midgut and hindgut
General gut development
Foregut - see below, supplied by coeliac trunk
Midgut - D2 -> transverse colon, supplied by SMA
Hindgut - transverse colon -> rectum, supplied by IMA
Foregut development
Foregut develops from cranial region of endoderm created just after initial
cephalocaudal folding of embryo
Rapid expansion to develop oesophagus (upper & lower respiratory buds
branch off this), asymmetrical expansion of stomach creates lesser curvature (ventral side)
and greater curvature (dorsal side) & duodenum forms 'C shape'
Foregut is anchored by both ventral and dorsal mesogastrium & foregut
rotation causes ventral and dorsal mesogastrium rotation too
oVentral mesogastrium lines the lesser curvature & first part of
duodenum, and the liver develops inside it
oDorsal mesogastrium lines the greater curvature & underside of
first part of duodenum, and the spleen develops inside it
Stomach sacs
oLesser sac develops posterior to stomach via rapid liver
development obliterated peritoneum on posterior wall (epiploic foramen is the only
entrance point to lesser sac)
oGreater sac develops anterior to stomach
Omentum
oLesser omentum is formed by ventral mesogastrium
oGreater omentum is formed by dorsal mesogastrium
Components
Upper and lower respiratory tracts
GIT - mouth (oral cavity, tonsils, tongue, salivary glands), pharynx,
oesophagus, stomach, D1 and D2 of duodenum
Associated - liver, gallbladder, pancreas
Spleen (it arises from mesoderm, however it shares the same blood supply
"coeliac artery' as other mature foregut structures)
Blood supply
Arterial - coeliac artery branches (supply all except pharynx, most of
oesophagus & respiratory system)
Venous - portal venous system
Lymphatics - drainage to pre-vertebral coeliac nodes at origin of coeliac
artery from aorta
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Summary
Ventral mesogastrium - lesser omentum, hepatogastric ligament,
hepatoduodenal ligament, falciform ligament (including ligamentum teres hepatis - the
round ligament of liver), coronary ligament; it only exists in the foregut
Dorsal mesogastrium - greater omentum, spleen, gastro-splenic ligament,
spleno-renal ligament; it extends through the whole gut tube
Epiploic foramen (foramen of Winslow)
oAnterior - portal vein, bile duct, hepatic artery
oPosterior - IVC, liver, right suprarenal gland, upper pole of right
kidney
oThe opening to the lesser sac
Anatomy 25cm fibromuscular tube that transports food from pharynx to stomach
Origin - inferior border of cricoid cartilage (C6) -> gastro-oesophageal junction at
cardiac orifice of stomach (T11 on LHS)
It runs left of midline
It descends downwards into superior mediastinum (T1-T4) -> right crus of
diaphragm through oesophageal hiatus (T10)
Muscular layers
Internal circular
External longitudinal - superior 1/3 (voluntary striated), middle 1/3
(voluntary striated + smooth muscle), inferior 1/3 (smooth muscle)
Peristalsis (rhythmic contractions of muscles) propagate food down
oesophagus
Anatomical relations
Thoracic - superior (trachea), posterior (vertebral bodies, descending aorta),
left (aortic arch, subclavian artery), right (pleura, terminal azygous vein)
Abdomen - anterior (left vagus nerve), posterior (right vagus nerve)
Oesophageal sphincters
Upper - anatomical striated muscle sphincter (cricopharyngeus muscle)
Lower - physiological sphincter (no specific muscle, but 4 features)
oOesophagus enters stomach at acute angle (angle of His)
oOesophagus walls at intra-abdominal section are compressed
during +ve intra-abdominal pressure
oMucosal folds help occlude lumen
oRight crus of diaphragm has 'pinch-cock effect'
oAt rest, the sphincter prevents gastric reflux & during peristalsis, the
sphincter relaxes to allow food entry
Blood supply
Thoracic Arterial supply
oThoracic aorta -> oesophageal arteries
oSubclavian artery -> thyrocervical trunk ->
inferior thyroid artery
Venous supply
oAzygous vein branches
oInferior thyroid vein
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Abdominal Arterial supply
oAbdominal aorta -> coeliac trunk -> left
gastric artery
oLeft inferior phrenic artery
Venous supply
oPortal circulation via left gastric vein
oSystemic circulation via azygous vein
Lymphatics
Superior 1/3 - deep cervical LN
Middle 1/3 - superior and posterior mediastinal LN
Inferior 1/3 - left gastric and coeliac LN
Nerve supply
Vagus nerve (motor)
Investigations Esophagogastroduodenoscopy (upper GIT endoscopy) + biopsy
24hr pH study - measure pH of oesophagus to demonstrate reflux of gastric acid
Manometry
Evaluate strength and function of oesophageal muscles & effectiveness of
peristalsis
Gastric emptying study
Measure movement of food through your stomach via radioactive
compound consumed with regular food (sandwich) + radiolabelled water to drink
Specialized camera takes pics (scans) of your stomach for 2hrs
Fibreoptic oesophagoscopy
Flexible endoscope is inserted through mouth into oesophagus
Provide visualization of oesophageal mucosa from UES to LES
This procedure is one of several procedures encompassing upper endoscopy
(gastroscopy, oesophagogastroduodenoscopy, enteroscopy etc)
Barium swallow
Patient swallows thick barium mixture in supine position & fluoroscopic
images of swallowing process are made
Patient swallows several thin barium mixtures & fluoroscopy and standard
radiographs record the passage of fluid
Epigastric pain GIT Oesophageal rupture
(Booerhaarve's disease)
PUD
GORD
Gastritis
Gastroenteritis
Gallstones (biliary colic, acute
cholecystitis)
Gastric/ pancreatic cancer
Pancreatitis
Acute appendicitis
Irritable bowel syndrome
Other MI
Ruptured aortic aneurysm
Pericarditis
Pleuritis
Pleurisy
Pneumonia
Dysphagia Difficulty swallowing
Etiology (local causes)
Lumen Foreign body
Inside wall Congenital atresia
Oesophageal stricture
Achalasia
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Document Summary
Briefly outline the embryology of the foregut, particularly in relation to blood supply of abdominal foregut structures would raise concern. Explain the relation between foregut structures and epigastric pain. List symptoms or gastro-oesophageal reflux disease (gord) including features that. Tabulate a stepwise management plan for gord, including the role of investigations. Describe the pathology and natural history of barrett"s oesophagus. Contrast the aetiological factors for scc and adenocarcinoma of the oesophagus. Understand the pathology of oesophageal achalasia and how it presents. Contrast how dysphagia behaves in the setting of a benign peptic stricture, Foregut embryology achalasia and cancer of the oesophagus. Anterior component of the alimentary canal running from mouth -> major duodenal papilla (d2 of duodenum) It arises from endoderm developing from the folding primitive gut & developmentally distinct from midgut and hindgut. Foregut - see below, supplied by coeliac trunk. Midgut - d2 -> transverse colon, supplied by sma. Hindgut - transverse colon -> rectum, supplied by ima.
