Embryo of CNS

Question 1

What is the mantle layer during CNS development?

Answer 1

Region that becomes the gray matter.

Question 2

What is the marginal layer during CNS development?

Answer 2

Region that becomes the white matter.

Question 3

What is the basal plate?

Answer 3

Eventually becomes the anterior horn and holds motor neuron cell bodies.

Question 4

What is the alar plate?

Answer 4

Eventually becomes the posterior horn and deals with sensory information.

Question 5

What is the sulcus limitans?

Answer 5

Divides anterior (motor) horn from posterior (sensory) horn.

Question 6

What are neural crest cells?

Answer 6

Ectoderm cells that migrate from the ectoderm into other germ layers and form ganglia, melanocytes, certain glial cells, and endocardial cushions.

Question 7

Neural tube defect in which the cranial neuropore fails to close.

Answer 7

Anencephaly

Question 8

Name the 3 primary brain vesicles and which general structures of the brain they form.

Answer 8

1. Prosencephalon - forebrain
2. Mesencephalon - midbrain
3. Rhombencephalon - hindbrain

Question 9

What is the mesencephalon flexure?

Answer 9

Bend in the developing CNS between the mesencephalon and the rhombencephalon.

Question 10

What is the cervical flexure?

Answer 10

Bend in the developing CNS at the junction of the spinal cord (myelon) and the myelencephalon.

Question 11

Name the secondary vesicles that arise from the primary vesicles.

Answer 11

Prosencephalon:

1. Telencephalon
2. Diencephalon

Mesencephalon:
1. Mesencephalon

Rhombencephalon:

1. Metencephalon
2. Myelencephalon

Question 12

Name the structures that arise from the secondary vesicles.

Answer 12

Telencephalon: cerebral hemispheres and lateral ventricles (1st and 2nd)

Diencephalon: thalamus, hypothalamus, epithalamus, subthalamus, & third ventricle

Mesencephalon: midbrain, cerebral aqueduct

Metencephalon: pons, cerebellum, upper 4th ventricle

Myelencephalon: medulla, lower 4th ventricle

Question 13

What is the rhombencephalic isthmus?

Answer 13

Narrowing of the brainstem between the pons and midbrain

Question 14

What is Rathke’s pouch?

Answer 14

Indentation of epithelial cells from the oral cavity into the diencephalon. Eventually forms the anterior pituitary.

Question 15

Remnants from Rathke’s pouch that are associated with diabetes insipidus and visual defects.

Answer 15

Craniopharyngiomas

compress the ant. pit. and optic chiasm

Question 16

Most of brain growth occurs after birth. What neurologic component of the brain accounts for the most growth at this time?

Answer 16

Myelin

Question 17

What is a “band heterotopia”?

Answer 17

Characteristic viewed on MRI indicating neuronal heterotopia. Indicates neurons that didn’t migrate correctly and usually results in seizures.

Question 18

What is the developmental condition that deals with midline defects?

Answer 18

Holoprosencephaly

Question 19

What causes microcephaly?

Answer 19

Failure of the brain to grow. The calvaria requires pressure from the growing brain to expand.

Question 20

What is schizencephaly?

Answer 20

Large clefts in the cerebral hemispheres continuous with ventricles.

Question 21

What is pachygyria?

Answer 21

Malformation of the cerebral hemispheres where too much cortex develops in a certain region. Usually results in seizures.

Question 22

What is Dandy Walker syndrome?

Answer 22

Failure of the cerebellum to form. The area is replaced by an enlarged 4th ventricle. Patients have no coordination or balance.

Question 23

What is Lissencephaly?

Answer 23

Decreased number or smooth cortical gyri. Associated with seizures.