GI development 2 Flashcards
What is the name of the connective tissue which grows to separate the respiratory diverticulum from the oesophagus?
Tracheoesophageal septum
When germ layer does the trachea and oesophagus develop from?
Endoderm
What creates the shiny covering of the liver?
Visceral peritoneum
Name the ligament which runs between the lobes of the liver, connecting it to the anterior abdominal wall:
Falciform ligament
In which parts of the GI tract is the lumen obliterated and requires recanalisation?
- Oesophagus
- Duodenum
- Small intestine
- Bile duct
During which week after fertilisation do the intestines herniate into the umbilical cord? Why does this happen?
Week 6
Rapid growth of the Liver and Intestines, before adequate growth of the abdominal cavity
What is the axis of the primary intestinal loop? (during mid-gut rotation)
SMA (superior mesenteric artery)
Which structure splits the mid-gut into cranial and caudal regions?
SMA (Superior Mesenteric Artery)
Describe mid-gut rotation:
- Mid-gut herniates into umbilical cord, with SMA as axis
- 3x 90’ turns anti-clockwise
- Cranial limb returns first (transverse colon passes in front of duodenum
- Cranial limb moves to the left side
By which week after fertilisation do the intestines return to the abdominal cavity (after mid-gut rotation)?
Week 10
List the adult derivatives of the cranial limb of the intestines:
- Distal duodenum
- Jejunum
- Proximal ileum
List the main derivatives of the caudal limb of the intestines:
- Distal ileum
- Caecum
- Appendix
- Asc. colon
- Prox 2/3rds transverse colon
Where is the most common site of incomplete recanalisation of the GI tract?
Upper duodenum
What is the usual cause of duodenal stenosis?
Incomplete recanalisation
What is the usual cause of pyloric stenosis?
How does pyloric stenosis present?
Hypertrophy of circular muscle around pyloric sphincter
Usually presents in childhood, causing projectile vomiting
What is the germ layer origin of the anal canal, ABOVE the pectinate line?
Endoderm
What is the germ layer origin of the anal canal, BELOW the pectinate line?
Ectoderm
What is the name of the line marking the division of the anal canal into endoderm and ectodermal origins?
Pectinate line
What is the blood supply to the anal canal ABOVE the pectinate line?
Superior Rectal Artery (from IMA)
What is the nerve supply to the anal canal ABOVE the pectinate line?
S2, 3, 4 Pelvic parasympathetic nerves
Above the pectinate line, what can the anal canal detect?
Stretch
What is the blood supply to the anal canal BELOW the pectinate line?
Pudendal artery
What is the nerve supply to the anal canal BELOW the pectinate line?
S2, 3, 4 Pudendal nerves
Below the pectinate line, what can the anal canal detect?
Pain
Touch
Temperature
What is the epithelium of the anal canal?
Above the pectinate line = simple columnar
Below the pectinate line = stratified squamous
- above Hilton’s white line = non-keratinised
- below Hilton’s white line = keratinised
To which nodes does the lymph drain to from the anal canal?
Above the pectinate line = Internal iliac nodes
Below the pectinate line = Superficial Inguinal nodes
What is an ‘imperforate anus’?
Failure of anal membrane to rupture
