Development of GI tract Flashcards
In which week does the embryo fold laterally and craniocaudally?
4th week
What are the structures in Foregut, midgut and hindgut?
foregut: oesophagus to duodenum (proximal to bile duct entrance), midgut: duodenum (distal to bile duct entrance) to proximal 2/3 transverse colon, hindgut: distal 1/3 transverse colon to internal lining of bladder and urethra
What is the blood supply to the foregut?
Celiac trunk
What is the blood supply to the midgut?
Superior mesenteric artery
What is the blood supply to the hindgut?
Inferior mesenteric artery
What is the intraembryonic coelom?
One large cavity in the embryo that later becomes the abdominal and thoracic cavities
which part of the gut does the ventral mesentery line?
Foregut ONLY
Where is the greater and lesser sac?
Greater sac is in front of the stomach, the lesser sac is behind the stomach
What forms the greater omentum?
specialised region of peritoneum formed from dorsal mesentery
What forms the lesser omentum?
specialised region of peritoneum formed from ventral mesentery
What is the difference between retroperitoneal and secondarily retroperitoneal?
retroperitoneal : were never in the peritoneal cavity and never had a mesentery. Secondarily retroperitoneal : initially invested by peritoneum and had a mesentery but loses this with development
Name the ligament that separates the left and right lobe of the liver
Falciform ligament
Name 2 secondarily retroperitoneal structures of the foregut
duodenum and pancreas
Why does the midgut leave the abdomen in development?
The cavity becomes too small due to rapid growth of the liver
Which structure acts as the axis for the rotation of the primary intestinal loop?
Superior mesenteric artery
How much does the midgut rotate?
270 degrees anticlockwise
Name 2 complications of rotation
Incomplete rotation (Left-sided colon) and reversed rotation (transverse colon posterior to duodenum)
Name 2 complications with volvulus
Strangulation and Ischaemia
What is the name of the structure that connects the primary intestinal loop to the yolk sac?
Vitelline duct
What is the most common remenant of the vitelline duct?
Meckel’s diverticulum
Define recanalisation
Cell growth is so rapid that the lumen of the gut tube closes, recanalisation re-opens the tube
What results if recanalisation is unsuccessful?
Atresia or stenosis
Define Pyloric stenosis
Hypertrophy of the circular muscle in the region of the pyloric sphincter causing projectile vomiting
Which 2 distinct structures form the anal canal?
Proctodeum and the cloaca
What is the lymphatic drainage above and below the pectinate line in the anal canal?
Above = Internal iliac nodes, Below = Superficial inguinal nodes
Name 2 hindgut abnormalities
Imperforate anus and Hindgut fistulae
