Development of the Midgut and Hindgut Flashcards
What does the midgut give rise to?
SI
Caecum, appendix
Ascending colon
Proximal 2/3 transverse colon
What is the primary intestinal loop?
As the midgut elongates it runs out of space = starts to loop
Connected to yolk sac by vitelline duct
Has cranial and caudal limbs
What is physiological gut herniation?
Elongation of the primary intestinal tube faster than the abdo causes the intestine to herniate into the umbilical cord
Outline the steps of rotation in the midgut
Rotation around the SMA
3 x 90 degree turns
Within the umbilical cord = first 90 degree counter-clockwise rotation
Abdo enlarges and intestine returns to abdo cavity
Further 180 degree counter-clockwise rotation = fixing to the posterior retroperitoneum
Achieve = midgut crosses over itself, transverse colon comes to lie anterior to duodenum/jejunum/ilium
Outline malrotation of the gut
Incomplete = left-sided colon
Reversed = transverse colon passes posterior to duodenum
What risk present with midgut rotation defects?
Volvulus = twisting, strangulation, ischaemia
If the vitelline duct persists what can occur?
Vitelline cyst
Vitelline fistula = direct communication between umbilicus + intestinal tract
Meckels diverticulum = basis for volvulus due to attachment to abdo wall
Describe recanalisation
Process of restoring the lumen that has become blocked due to rapid cell growth
Occurs in = oesophagus, bile duct, SI
If wholly/partial = atresia or stenosis of structure
Discuss pyloric stenosis
Hypertrophy of the circular muscle in the region of the pyloric sphincter
NOT a recanalisation failure
Characteristic projectile vomiting
What type of vomiting will be seen in a pt with midgut volvulus?
Bilious as obstruction is after the bile duct
What is gastroschisis?
Failure of abdo wall to close
Leaves gut tube outside the body cavity
What is an omphalocoele?
Persistent physiological gut herniation
Surrounded by peritoneum
What structures do the hindgut give rise to?
Distal 1/3 transverse colon
Descending colon
Rectum
Superior part of anal canal
Epithelium of urinary bladder
What is the pectinate line?
Line which divides the upper two thirds and lower third of the anal canal
Created by junction between 2 embryonic germ layers
Above = visceral innervation
Below = somatic innervation
Outline the visceral pain of the gut
Foregut = epigastric
Midgut = periumbilical
Hindgut = suprapubic
