Neuro Embryology

Question 1

Induces overlying ectoderm to differentiate into neuroectoderm and form neural plate

Answer 1

Notochord

Question 2

Gives rise to neural tube and neural crest cells

Answer 2

Neural plate

Question 3

What does the notochord becomes in the adult?

Answer 3

The nucleus pulposus of intervertebral disc

Question 4

Alar plate

Answer 4

Dorsal: sensory

Question 5

Basal plate

Answer 5

Ventral: Motor

Question 6

Adult derivatives of telencephalon

Answer 6

Cerebral hemispheres and lateral ventricles

Question 7

Adult derivatives of Diencephalon

Answer 7

Thalamus and third ventricle

Question 8

Adult derivatives of mesencephalon

Answer 8

Midbrain and aqueduct

Question 9

Adult derivatives of Metencephalon

Answer 9

Pons, cerebellum ad upper part of fourth ventricle

Question 10

Adult derivatives of Myelencephalon

Answer 10

Medulla and lower part of fourth ventricle

Question 11

Neuroectoderm gives rise to…

Answer 11

CNS neurons, ependymal cells (inner lining of ventricles, make CSF), oligodendroglia, astrocytes

Question 12

Neural crest gives rise to…

Answer 12

PNS neurons, Schwann cells

Question 13

Mesoderm gives rise to…

Answer 13

Microglia (like Macrophages, originate from Mesoderm)

Question 14

Spina bifida occulta

Answer 14

Failure of bony spinal canal to close, but no structural herniation. Usually seen at lower vertebral levels. Dura is intact. Associated with tuft of hair or skin dimple at level of bony defect. Normal AFP.

Question 15

Meningocele

Answer 15

Meninges (but no neural tissue) herniate through bony defect.

Question 16

Meningomyelocele

Answer 16

Meninges and neural tissue herniate through bony defect.

Question 17

Anencephaly

Answer 17

Malformation of anterior neural tube Žleading to no forebrain, open calvarium. Clinical findings: elevated AFP; polyhydramnios (no swallowing center in brain). Associated with maternal type 1 diabetes.
Maternal folate supplementation lowers risk.

Question 18

Holoprosencephaly

Answer 18

Failure of left and right hemispheres to separate; usually occurs during weeks 5–6. May be related to mutations in sonic hedgehog signaling pathway. Moderate form has cleft lip/palate, most severe form results in cyclopia. Seen in Patau syndrome and fetal alcohol syndrome.

Question 19

Chiari II

Answer 19

Significant herniation of cerebellar tonsils and vermis through foramen magnum with aqueductal stenosis and hydrocephalus. Often presents with lumbosacral meningomyelocele, paralysis below the defect.

Question 20

Dandy-Walker

Answer 20

Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills the enlarged posterior fossa). Associated with hydrocephalus, spina bifida.

Question 21

Syringomyelia

Answer 21

Cystic cavity (syrinx) within spinal cord (if central canal Ž hydromyelia). Crossing anterior spinal commissural fibers are typically damaged first. Results in a “cape-like,” bilateral loss of pain and temperature sensation in upper extremities (fine touch sensation is preserved). Most common at C8-T1. Associated with Chiari malformations, trauma, and tumors.