CNS Development

Question 1

What, generally, do the neural crest, neural tube, and the lumen of the neural tube give rise to?

Answer 1

neural crest = PNS

Neural tube = CNS

Neural tube lumen = Ventricles

Question 2

What is anencephaly? What are the characteristsics?

Answer 2

Failure of closure of the neural tube at the cranial end

Absence of the skull and brain with a “frog-like” appearance

Question 3

What is spina bifida occulta? what is a typical finding on the skin over the development abnormality

Answer 3

failure of closure of the vertebral arch

dimple or patch of hair

Question 4

What is meningocele?

Answer 4

meningo- = meninges

-cele = hernia

hernaition of the meninges through the unformed vertebral arch

Question 5

What is meningomyeloocele?

Answer 5

meningo- = meninges

myele- = of the spinal cord

-cele = hernia

hernaition of the meninges and spinal cord through the unformed vertebral arch

Question 6

What is cerebral aqueduct stenosis? Which ventricles will enlarge as a result? Will the baby’s head be enlarged?

Answer 6

congenital stenosis of the canal that connects the 3rd and 4th ventricles

lateral and 3rd ventricles

YES! the baby’s skull has not completely fused together, so it will become enlarged

Question 7

What is Dandy-Walker malformation? What does it cause?

Answer 7

Congenital failure of the cerebellar vermis to develop. The vermis is what separates/connects the two sides of the cerebellum.

Dilation of the 4th ventricle (no vermis, 4th ventricle can expand)

Question 8

Describe the differences of Chiari Type I, II, and III malformations.

Answer 8

Chiari type I is congenital extension of the cerebellar tonsils through the formamen magnum (by 5mm or more) which can cause obstruction of CSF flow -> hydrocephalus

Chiari type II is the same thing as type I plus there is a myelomeningocele

Chiari type III is herniation of the cerebellar tonsils plus a myelomeningocele at the foramen magnum; they are associated with anencephaly

Question 9

What are the 3 types of neuronal migration disorders?

Answer 9

Holoprosencephaly

Heterotopias

Lissencephaly

Question 10

After the cranial neural tube closes at approximately day _____, three swellings develop. These are called…?

Answer 10

Day 25

1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)

Question 11

What intermediate structures do the prosencephalon give rise to? What adult structures do these ultimately become?

Answer 11

Prosencephalon -> telencephalon and diencephalon

Telencephalon -> cerebral hemispheres and lateral ventricles

Diencephalon -> thalamus, hypothalamus, and third ventricle

Question 12

What is your Dx?

Answer 12

Chiari type III malformation (myelomeningocele at the foramen magnum)

Question 13

What is your Dx?

Answer 13

Lissencephaly (neuronal migration disorder that leads to an absence of sulci)

Question 14

What is holoprosencephaly?

Answer 14

Abnormal cleavage of the prosencephalon -> telencephalon and diencephalon; results in inadequate forebrain development. Usually fatal.

Question 15

What is your Dx?

Answer 15

Heterotopia (gray matter where there should be white matter - neuronal migration disorder)