Development of the GIT Flashcards
How prevalent is Meckel’s diverticulum?
2% of the population
Where is Meckel’s diverticulum located?
2 feet from the ileocaecal valve
How long is a Meckel’s diverticulum?
2 inches (5cm) long
What is a Meckel’s diverticulum?
A remnant of the vitello-intestinal duct that extends from the mid gut to the yolk sac
When is the vitello-intestinal duct expected to close?
9th week of gestation
When do people usually present with Meckel’s diverticulum?
2 years of age
What kind of ectopic tissue might be found in a Meckels diverticulum?
Pancreatic and gastric mucosa
What is the innervation for the foregut?
T5-T9
What is the blood supply to foregut?
Coeliac artery
What forms the serosal layer of the GIT?
Splanchnic lateral plate of the mesoderm
Which part of the duodenum is contained within the foregut?
The first 2 parts
Which part of the duodenum within the midgut?
The second 2 parts
Which structures compose the foregut?
Oesophagus and 1st 2 parts of duodenum Liver Pancreas Gallbladder Spleen
What is the innervation of the midgut?
T10-T11
What is the blood supply to the midgut?
Superior mesenteric artery
What is the midgut composed of?
Last 2 sections of the duodenum, jejunum, caecum, ascending colon, proximal 2/3 of transverse colon
How does the stomach rotate during embryology?
It rotates 90 degrees clockwise
When does the midgut retract into the abdominal cavity?
During the 10th week of development
How much does the intestines rotate during embryonic development?
240 degrees anti-clockwise
When does the midgut herniate out of the abdominal cavity?
During 6th week of development
Define an omphalocoele
Indirect herniation of the intestines via the umbilicus, the intestines are surrounded by a layer of amnion and this condition is often associated with chromosomal abnormalities
Define gastroschisis
Direct herniation of the intestines through the abdominal wall. The intestines are not covered in amnion and therefore can be damaged by amniotic fluid and the condition is not associated with chromosomal abnormalities
Which type of gut herniation is associated with chromosomal abnormalities?
Omphalocoele
Which type of gut herniation results in intestines being damaged by the amniotic fluid?
Gastroschisis
What does the hindgut consist of?
Distal 1/3 of the transverse colon, descending colon, sigmoid colon, rectum, and 1st half of the anal canal
What is the blood supply to the hindgut?
Inferior mesenteric artery
What is innervation of the hindgut?
T12-L1
Which embryological structure gives rise to the myenteric plexus?
Ectodermal neural crest cells
What is the function of Ladds Bands?
Attach caecum to RLQ retroperitoneum
How might Ladd’s Bands be affected in intestinal malrotation?
Malrotation can lead to Ladds bands attaching the caecum the RUQ leading to intestinal obstruction
When does meconium first appear in the terminal ileum?
10-16 weeks
When does the thyroid gland start functioning?
Approximately 12th week of gestation
