Gut Anatomy & Clinical Applications Flashcards
4 phases of swallowing
Oral preparation (mastication)
Oral transit - voluntary, tongue moves bolus posteriorly
Pharyngeal - involuntary
oesophageal - involuntary, sphincters
Define deglutination
Swallowing
Skeletal and SM
Complex movement
Cranial nerves involved in swallowing
V - trigeminal VII - facial X - vagus IX - glossopharyngeal XII - hypoglossal
Parts of oesophagus
- cervical (cricopharyngeus to thoracic inlet)
- thoracic (to hiatus)
- abdominal (to gastro-oesophageal junction)
How long is the oesophagus?
Approx 25cm
3 normal narrowings of oesophagus where large objects can get stuck
- cervical constriction = cricoid cartilage
- thoracic constriction = aortic arch & L main bronchus
- diaphragmatic constriction = diaphragmatic hiatus
Blood supply to oesophagus
- cervical = inferior thyroid from subclavian
- thoracic = aorta
- abdominal = coeliac plexus from L gastric artery
Venous supply of oesophagus
- cervical to inferior thyroid veins to SVC
- thoracic to azygous system
- abdominal to left gastric vein via portal system
(porto-systemic anastomoses)
Oesophageal hiatus
T10
Right crux of diaphragm fibres
Left side of median plane
Oesophagus, L. gastric vessels, lymphatics from oesophagus lower 1/3 and vagus nerve pass through
Aortic hiatus
T12
Median plane
Aorta, thoracic duct and azygos vein pass through
Vena cava hiatus
T8
Right side of median plane
IVC and right phrenic nerve pass through
Oesophageal sphincter
Physiological
SM of oesophagus
Skeletal muscle of crural diaphragm
Prevents of reflux of food from the stomach
Hiatus hernia how?
No formal sphincter just physiological
Oesophageal sphincter becomes dilated
Hiatus hernia symptoms
Reflux Bloating Sore throat Hoarse voice (globus sensation)
Sliding hiatus hernia
Part of stomach rises directly through hiatus
Paraesophageal hiatus hernia (rolling)
Part of stomach folds up onto oesophagus and herniates through diaphragm
Much more dangerous
Can become strangulated = need emergency surgery
Where do the phrenic arteries pass?
Underneath the diaphragm
Branches of the celiac trunk
L gastric
Common hepatic artery
Splenic artery
Abdominal aorta branches
First phrenic arteries Then celiac trunk Then SMA = small bowel IMA = left colon and superior rectum Renal arteries Gonadal arteries
Which branches pass anteriorly to the oesophagus
Celiac trunk
SMA
IMA
What branches pass laterally to the oesophagus?
Renal arteries
Gonadal arteries
Retroperitoneal unlike anterior branches which pass into peritoneum
Anatomy of stomach
Abdominal oesophagus Cardiac sphincter Fundus Cardia Body Lesser and greater curve Antrum Pylorus Pyloric sphincter Duodenum
Arterial supply of stomach
L gastric artery = lesser curve up to oesophagus
R gastric artery is branch of hepatic artery = lesser curve to anastomose with L gastric artery
Right gastroepiploic artery from hepatic artery = greater curve
Left gastroepiploic artery from splenic = greater curve
Short gastric arteries from splenic = fundus of stomach
4 parts of the duodenum
Superior
Descending
Inferior
Ascending
In that order
Which parts of the duodenum are retroperitoneal?
2nd to 4th
Descending, inferior, ascending
All expect for superior
Blood supply of duodenum
Gastroduodenal from R hepatic artery behind first section of duodenum and gives rise to superior pancreaticoduodenal arteries
Inferior pancreaticoduodenal artery from SMA
All also supplies pancreas
Where is the duodenal papilla?
Medial part of 2nd part (descending part) of duodenum
Where common bile duct empties and pancreatic duct empties
Retroperitoneal
Bile tree
R and L hepatic ducts join to form hepatic duct
Cystic duct from gall bladder joins with hepatic duct forming common bile duct
Common bile joins with pancreatic duct emptying into major duodenal papilla
Sometimes there is an accessory pancreatic duct which will empty into a minor duodenal papilla
Hepatopancreatic ampulla
Common bile duct and pancreatic duct combining
Where is bile produced?
Liver
Stored in the bile duct
Embryological blood supply of gut
Foregut = celiac trunk
Mid gut = SMA
Hind gut = IMA
Foregut
Stomach to 2nd part of duodenum
Mid gut
3rd part of duodenum to 2/3 of transverse colon
Hind gut
Rest of colon to superior rectum
Visceral innervation
Visceral = dull pain, not well localised, referred pain
Less sensitive to direct trauma
Low density of innervation
Foregut Injury pain referred where? and examples
Pain in epigastrium Cholecystitis Pancreatitis Gastritis Biliary colic
Midgut injury pain referred where? and examples
Umbilicus
Appendicitis
Small bowel obstruction
Hindgut injury pain referred where? and examples
Suprapubic region
Sigmoid diverticulitis
Colonic obstruction
Somatic innervation
Well localised sensation
Stabbing/sharp
Multiple nerve fibres
Ileocolic branch
From SMA
Terminal ileum and cecum
What supplies the midgut colon?
SMA = ileocolic branch, right and middle colic arteries
What supplies the hindgut?
IMA = left colic artery, sigmoid artery to superior rectal
Middle and inferior rectal arteries come from external iliac artery
Watershed area
Crossover between SMA and IMA Marginal artery Splenic flexure Susceptible to colonic ischaemia Consider during colorectal surgery - do not perform anastomoses in this area
Mesenteric ischaemia (important to distinguish with ischaemia colitis!!)
SMA proximal problem Sudden Thromboembolic cause Total blood loss Severe pain Operative Tx
Ischaemic colitis (important to distinguish with mesenteric ischaemia!!)
SMA More distal problem Hourly onset Multi causes Transient blood loss as collateralisation of blood supply Diarrhoea, PR bleeding ,pain Conservation/operative Tx
Rectal blood supply
Superior = IMA - superior rectal artery Middle = internal iliac - middle rectal Inferior = internal iliac - internal pudendal - inferior rectal
Calot’s triangle
Cystic duct Common hepatic duct Inferior surface of liver Cystic artery runs in triangle Clipping on cystic duct but not too low that you clip on common bile duct
Oesophageal varices Cause
Liver cirrhosis = increase in vascular resistance
Portal HTN as increased hepatic resistance, decreased hepatic outflow and splanchnic arterial vasodilation (more inflow)
Varices as dilation of vessels in oesophagus and stomach
Increase in size with severity of portal HTN and can rupture/bleed when pressure exceeds a maximal point
Azygos blood flow instead which is not used to high pressure flow
Porto-systemic circulation sites
Lower 1/3 of oesophagus (L gastric meets azygos)
Umbilicus (umbilical meets superior/inferior epigastric veins)-> caput medusae
Upper anal canal (superior rectal vein meets middle/inferior rectal veins) -> anal varices
Bare area of liver (hepatic/portal veins meet inferior phrenic vein)
Duodenal artery route
Posteriorly to duodenum
Ulcers perforate posteriorly into artery = bleeding
Anterior perforation = into peritoneal cavity as first part of duodenum is intraperitoneal= free air = seen on CXR
Anterior Duodenal ulcers
Pain
Pneumoperitoneum imaging
Operative management
Posterior duodenal ulcers
Pain & bleeding
Normal imaging
Endoscopy/operative Tx
Ischaemic Bowel
Total or segmental
Acute cholecystitis
Stone impacted in Hartmann’s pouch = can cause oedema, infection
Peritonism if stone irritates peritoneum
Initially sterile
Secondary infection
Gall Bladder Disease Stages/types
Biliary colic = gall bladder not inflamed, stone impacting hartmann’s pouch = pain, after eating, radiates to back as referred from midgut, with heavy meals
Stone impacted in gall bladder neck, mucus from gall bladder lining cannot escape, mucus seal causes pain, if infected = cholecystitis, repeated bouts = gall bladder inflamed and fibrous
Stones escape out of pouch into common bile duct = obstructed = jaundice, if infected = cholangitis, life threatening, sepsis risk
2 ways to recognise cholangitis
Charcot’s triad
Reynold’s pentad
Charcot’s triad
Jaundice
RUQ pain
Fever/rigors
Cholangitis
Reynold’s pentad
Charcot’s triad
+ confusion and hypotension
Appendicitis
Midgut pain
Migratory RIF
Inflammation to anterior abdominal wall = more localised pain
Causes of appendicitis
Obstruction to appendix
- lymphangitis
- appendiclolith
- foreign body
- worms
Mechanism of appendicitis
Increased pressure in appendix wall =
- venous stasis
- thrombosis
- lymphatic obstruction
- swelling
