Flashcards in Embryology 2 Deck (60)
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31
Lymphatic drainage of the anal canal below the pectinate line
Superficial inguinal nodes
32
What sensations are possible above the pectinate line
Only stretch
33
What sensations are possible below the pectinate line
Temperature
Touch
Pain
34
What is Meckel's diverticulum
A 'cul-de-sac' in the ileum
35
What complication is seen in Meckel's diverticulum
Ulceration
Ectopic gastric/pancreatic tissue in the diverticulum secretes enzymes and acids
36
Why is Meckel's diverticulum said to follow a rule of 2's
2% population affected
2 feet from the iliocecal valve
2 inches long
Affects males twice as often as females
Usually detected in under 2's
37
What is a vitelline cyst
Vitelline duct that forms fibrous strands at either end
38
What is vitelline fistula
Direct communication between the umbilicus and intestine
39
What is patent urachus
The urachus (fibrous remnant of allantois) fails to close so there is a direct communication between the umbilicus and the bladder
40
What is omphalocoele
Persistence of a physiological herniation so part of the gut fails to return to the abdominal cavity
Since the umbilical cord is covered by a reflection of the amnion, an epithelial layer covers the defect
41
What is gastroschisis
Failure of the abdominal wall to close during embryonic folding leaving the gut tube outside the body cavity
Unlike omphalocoele, there is no covering over the gut tube
42
What are the hindgut abnormalities
Imperforate anus
Anal agenesis
Hindgut fistulae
43
What is imperforate anus
Failure of the anal membrane to rupture
Also called anal atresia
44
What is anal agenesis
Failure of development of the anal canal
45
What is hindgut fistulae
Abnormal connection within the hindgut
46
Why is recanalisation necessary in some structures of the gut tube
Cell growth becomes so rapid that the lumen is partially or completely occluded
47
What occurs in failure of recanalisation
Atresia (complete failure)
Stenosis (partial failure)
48
What's the order of incidence of atresia/stenosis in the gut
Duodenum
Jejunum and ileum
Colon
49
What's the most common cause of atresia in the upper duodenum
Recanalisation failure
50
What's the most common cause of atresia in the lower duodenum
Vascular accident - there is a loss of blood supply and part of the gut dies
Caused by malrotation, volvulus and body wall defects
51
What is pyloric stenosis
Narrowing of the exit from the stomach causing projectile vomiting
52
Causes of pyloric stenosis
Hypertrophy of the circular muscle in the region of the pyloric sphincter
53
Which structures of the midgut retain mesenteries
Jejunum
Ileum
Appendix
Transverse colon
54
Which structures of the midgut have fused mesenteries
Duodenum
Ascending colon
55
Which structures of the hindgut retain mesenteries
Transverse colon
Sigmoid colon
56
Which structures of the hindgut have fused mesenteries
Descending colon
Rectum
57
When is cloacal partitioning complete
End of Week 7
58
When does cloacal partitioning begin
Week 6
59
When does a patent urachus present
At birth
In men it can present later in life - high pressure caused by obstruction of bladder outflow (by benign prostatic hypertrophy) can lead to opening of urachus
60
