brain embryology

Question 1

lateral neck cyst that doesn’t move with swallowing

Answer 1

branchial cleft cyst: 2nd, 3rd, 4th clefts form a persistent cervical sinus

Question 2

midline neck cyst that moves with swallowing

Answer 2

thyroglossal duct cyst

Question 3

thymic aplasia
T cell deficiency
hypocalcemia

Answer 3

DiGeorge Syndrome: abnormal 3rd + 4th branchial pouch

Question 4

anterior 2/3 of tongue comes from what branchial arch?

Answer 4

1st branchial arch

Question 5

posterior 1/3 of tongue comes from what branchial arch?

Answer 5

3rd + 4th branchial arch

Question 6

mandibular hypoplasia can be caused by which branchial arch syndrome?

Answer 6

Treacher Collins Syndrome:

1st arch neural crest cells don’t migrate

Question 7

fistula between tonsil area and lateral neck is due to what branchial arch abnormality

Answer 7

pharyngealcutaneous fistula: 2nd arch

Question 8

when neuropores fail to fuse during 4th week → persistent connection between amniotic cavity and spinal canal this causes

Answer 8

neural tube defects

Question 9

3 types of neural tube defects (occur in lumbrosacral region)

Answer 9

spina bifida occulta
meningocele
meningomyelocele

Question 10

etiology of neural tube defects

Answer 10

low folic acid before conception and during pregancy

Question 11

quad screen suggesting a neural tube defect or abdominal wall defect shows:

Answer 11

↑ maternal αfetoprotein (AFP)

Question 12

quad screen suggesting down syndrome shows:

Answer 12

↓ maternal αfetoprotein (AFP)

Question 13

amniocentesis suggesting a neural tube defect or abdmonial wall defect shows:

Answer 13

↑maternal αfetoprotein (AFP)

Question 14

tuft of hair in lumbrosacral region
failure of bony spinal canal to close
dura intact
no herniation

Answer 14

spina bifida occulta (mildest neural tube defect)

Question 15

meninges herniate through spinal canal defect (not spinal cord)

Answer 15

meningocele

Question 16

meninges + spinal cord herniate through spinal canal defect

Answer 16

meningomyelocele

Question 17

2 types of forebrain anomalies

Answer 17

anencephaly

holoprosencephaly

Question 18

cranial neural tube malformation → open calvarium → brain tissue exposed to acidic amniotic fluid → forebrain dissolved

Answer 18

anencephaly

Question 19

↑AFP (in maternal serum and amniotic fluid) + polyhydramnios + frog like appearance

Answer 19

anencephaly (a neural tube defect)

Question 20

left + right hemis don’t separate
cleft lip/palate (moderate form)
cyclopia (most severe)

Answer 20

holoprosencephaly

Question 21

all of these can cause:
sonic hedgehog signaling pathway
severe FAS
trisomy 13

Answer 21

holoprosencephaly

Question 22

agenesis of cerebellar vermis + cystic enlargement of 4th ventricle (fills posterior fossa)

Answer 22

dandy-walker syndrome

Question 23

posterior fossa malformation that presents with hydrocephalus + spina bifida

Answer 23

dandy-walker syndrome

Question 24

cerebellar tonsils herniate through foramen magnum→ compress spinal cord → syringomyelia

Answer 24

chiari I malformation (most mild)

Question 25

lumbrosacral myelomeningocele → causes significant cerebellar/vermis herniation through foramen magnum→ over time: stenosis of cerebral aqueduct + hydrocephalus (enlarged ventricle)

Answer 25

chiari II malformation

Question 26

cystic cavity in spinal cord (usually C8-T1)

Answer 26

syringomyelia

Question 27

“cape-like” bilateral loss of pain + temperature in arms + shoulders with possible hand+arm weakness

Answer 27

syringomyelia:
spinothalamic tract crosses in anterior white commissure - first affected (bilateral loss of pain + temp in UE)
anterior horn of motor neurons also possible if extends laterally (hand muscle weakness)

Question 28

chiari I or spinal trauma (mos-yrs later) can cause this

Answer 28

syringomyelia

Question 29

↑AFP in maternal serum/amniotic fluid+ ↑acetylcholinesterase amniotic fluid + abnormal sonogram suggest

Answer 29

neural tube defect