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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

How do you distinguish a vitelline fistula and patent urachus

Inject contrast into cyst and see whether dye goes into bladder or intestines