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MRCOG Part one > Embryology Development & Congenital anomalies of the GI tract > Flashcards

Embryology Development & Congenital anomalies of the GI tract Flashcards

1
Q

What are the derivatives of the foregut?

A 
Oesophagus
Trachea and lung buds 
stomach
Duodenum proximal to entrance of bible duct 
Liver, biliary apparatus and pancreas
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2
Q

What are the derivatives of the midgut?

A

Duodenum distal to opening of bile duct
Small intestine
Caecum and appendix
Ascending colon and 2/3rds of transverse

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3
Q

What are the derivatives of the hindgut?

A

Distal 3rd of transverse colon, descending colon, sigmoid colon
Rectum and superior part of anal canal
Epithelium of bladder & most of urethra

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4
Q

What is the arterial supply to the foregut?

A

Coeliac trunk

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5
Q

What is the arterial supply to the midgut?

A

SMA

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6
Q

What is the arterial supply to the hindgut?

A

IMA

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7
Q

Describe the characteristics of the oesophageal muscle, upper 2 res vs lower 1 third

A

Upper 2/3: Striated muscle innervated by vagus nerve

Lower 1/3: Smooth muscle innervated by splanchnic plexus

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8
Q

Describe the rotation of the stomach.

A

Turns 90 degrees on the longitdinal axis so left side is anterior and right posterior
AP rotation, caudal part moves right and upward

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9
Q

Where is the lesser omentum

A

between lesser curve of stomach and liver

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10
Q

Where is the falciform ligament

A

liver to ventral wall of abdominal wall

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11
Q

At what week does haematopoiesis begin giving the liver its read appearance

A

week 6

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12
Q

At what week does bile formation start?

A

Week 12 → dark green bowel contents

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13
Q

Briefly describe the embryology of the pancreas.

A

Th larger dorsal pancreatic bud develops 1st, a ventral pancreatic pub develops near the entry of the bille duct.
The dorsal pud is a accessory duct to the duodenum (minor papilla) and the ventral bud has the main pancreatic duct (major papilla)

As the duodenum rotates the two buds form and the main duct remains patent whilst the accessory duct closes. This fails to close in 10%.

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14
Q

When does insulin secretion start?

A

Month 5 - islets of langerhan

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15
Q

Why does physiological herniation of the midgut occur?

A

As the midget elegonates rapidly as does the size of the liver, there is not enough space within the developing abdominal cavity, therefore at week 6 the loops entry the extra embryonic cavity in the umbilical cord → physiological herniation

It renters at week 10.

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16
Q

Which is the last part of the gut to reenter the abdominal cavity

A

Caecum

Then descends in LIF, as descends appendix produced as a diverticulum

17
Q

What structures are retroperiteonal (anterior side has peritoneum)

A

Duodenum (except fist 2.5cm)
Ascending colon
Descending colon

18
Q

What structures retain their free mesenteries

A

Jejenum and ileum
Lower and of caecum and appendix
Transverse colon (fuses with posterior wall o f greater omentum)
Sigmoid colon

19
Q

Describe the connection of the urogenital system and hindgut at week 5

A

The allantois (future urogenital sinus) and hindgut unite at the cloaca (all endoderm) which comes into contact with the surface ectoderm at the cloacal membrane.

An area of mesodermal tissue between the allantois and hindgut→ the urorectal septum

20
Q

How does the allantois/hingut/urorectal change as the future develops

A

The urorectal septum moves closer to the cloacal memabrane/
At week 7 the cloacal membrane breaks down which creates an opening of the anal canal and a ventral opening for the urogenital sinus. The tip of the urorectal septum forms the perineal body.

Proliferation of the ectoderm → proctodeum the lowest region of the anal canal

21
Q

Describe the embryological orgins of the anal canal

A

Superior 2/3 endoderm of the hindgut
Inferior 1/3 ectoderm of proctoderm
Junction pectinate late, just below anal columns

22
Q

Arterial supply of superior 2/3rds of anal canal

A

Superior rectal artery (cont. of IMA)

23
Q

Arterial supply of inferior 1/3rd of anal canal

A

Inferior rectal artery (branch of internal pudendal artery)

24
Q

Venous drainage of superior 2/3rds of anal canal

A

Superior renal vain (inferior mesenteric vein)

25
Q

Venous drainage of inferior 1/3rd of anal canal

A

inferior rectal vein (internal pudendal vein)

26
Q

Lymphatic drainage

  • superior 2/3rds of anal canal
  • inferior 1/3rd of anal canal
A
  • Inferior mesenteric nodes

- Superficial inguinal lymph noses

27
Q

Nerve supply

  • superior 2/3rds of anal canal
  • inferior 1/3rd of anal canal
A
  • Autonmoic nervous system ‘painless carcinoma’

- Inferior rectal nerve

28
Q

How does oesophageal atresia present antenatally & postnatally

80-90% is associated with what additional abnormality

A

Antenatal: polyhydramnios
Postnatal: excessive drooling and regurgitation, inability to pass NG tube

trachea-oesophageal fistula
Maybe associated with anorectal atresia dan abnormality of urogenital system

29
Q

Where does duodenal stenosis most often occur?
What syndrome is it associated with?
How does it present antenatally & post nataly

What is the sign on XR?

A

Failed recanulisation - junction of the bile duct/pancreatic duct
Associated with downs syndrome (1/3)
AN: Polyhydramnios
PN: Bilious vomit abd distension of epigatrum

XR: Double bubble sign

30
Q

What does Kasai portoenterostomy treat?

A

Congenital extraheptic biliary atresia

31
Q

What is an annular pancreas

A

Ventral bud of pancreas move in opposite directions around the duodenum.

32
Q

What is the difference between gastroschsis and omphalocele

A

Gastrochesis: herntaiton of the abdominal contents, not covered by peritoneum through the para umbilical defect.

Omphalocele: Herniation of abdominal viscera covered in amnion through umbilical vein, failure of return of physiological herniation

33
Q

What is the prognosis of gastroschsis and omphalocele

A

Gastroshsis - good, surgical repair
omphalocele - often associated with other genetic abnormalities (cardiac/neural tube) - depends on this. High mortality rate 25%

34
Q

What is a meckle diverticulum? Where does it occur?

A

Persisting small portion of vitelline duct, forming outpocketing of diverticulum. Approx 40-60cm from ileocaecal valve

can mimic appendicitis

35
Q

What is the cause of congenital megacolon (hirschsprung)?

A

Absent parasymapthetic ganglia in the bowel wall, neural crest cells fail to migrate into the wall of the colon.

MRCOG Part one (28 decks)

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