Embryo

Question 1

Neurulation: what is it, when does it occur?

Answer 1

Folding process in which the neural plate becomes the neural tube. Day 15.

Question 2

Neuroepithelial cells line what and differentiate into what?

Answer 2

Line walls of neurotube. Differentiate into neuroblast.

Question 3

3 layers of neural tube?

Answer 3

Ependymal layer, mantle layer, marginal layer

Question 4

Mantle layer differentiates into?

Answer 4

Alar and basal plates

Question 5

Alar plate forms what in the spinal cord?

Answer 5

Dorsal horn (sensory)

Question 6

Basal plate forms what in the spinal cord?

Answer 6

Ventral horn (motor)

Question 7

Marginal layer makes?

Answer 7

White matter

Question 8

Neural crest cells form?

Answer 8

Ganglia, schwann cells, meningies, melanocytes, CT of the skull, smooth muscle of eye, optic nerves, chromaffin cells, endocardial cushion

Question 9

Anencephaly?

Answer 9

Failure of cranial neuropore to close. Associated degeneration of brain tissue.

Question 10

Cranial neuropore forms what 3 things?

Answer 10

Prosencephalon, mesencephalon, rhombencephalon

Question 11

Prosencephalon forms what 2 secondary vesicles?

Answer 11

Telencephalon, diencephalon

Question 12

Rhombencephalon forms what 2 secondary vesicles?

Answer 12

Metencephalon, mylencephalon

Question 13

Telencephalon forms what?

Answer 13

Cerebral hemispheres, lateral ventricle

Question 14

Diencephalon forms what?

Answer 14

Thalamus, hypothalamus, epithalamus, subthalamus, 3rd ventricle

Question 15

Mesencephalon forms what?

Answer 15

Midbrain and cerebral aqueduct

Question 16

Metencephalon forms what?

Answer 16

Pons, cerebellum, upper 4th ventricle

Question 17

Myelencephalon forms what?

Answer 17

Medulla and lower 4th ventricle

Question 18

Segmentation of CNS at 5 weeks?

Answer 18

Rhombencephalic isthmus, pontine flexure (separates mylencephalon and metacephalon)

Question 19

Myelon forms what?

Answer 19

Spinal cord

Question 20

The pituitary gland (hypophysis) develops from what 2 embryonic tissues?

Answer 20

Stomodeum (oral ectoderm that makes Rathke’s pouch) and diencephalon

Question 21

Craniopharyngiomas?

Answer 21

Benign brain tumor derived from pituitary gland embryonic tissue. Sx include visual and pituitary deficits (diabetes)

Question 22

Motor nuclei in the brainstem: developed from what and location?

Answer 22

Developed from basal plates. Located more midline.

Question 23

Sensory nuclei in the brainstem: developed from what and location?

Answer 23

Developed from alar plates. Located more laterally.

Question 24

Around when does the neural tube start to look like a brain?

Answer 24

Day 50

Question 25

Sulci and gyri start to form at what time?

Answer 25

30 weeks

Question 26

Describe neuroblast migration in the brain.

Answer 26

One wave of neuroblasts form, migrate to under the pia matter. Then a second wave of neuroblasts form and migrate to under the pia matter as well. Result is that the newer neuroblasts are closer to the surface

Question 27

When does most of the growth of the brain occur and what is it due to?

Answer 27

Growth of the brain is due to myelination and most growth takes place after birth (begins in 3rd trimester though)

Question 28

Double cortex syndrome/band heterodropia?

Answer 28

Failure of the neuroblasts to migrate to the surface, associated with seizures and developmental delays. Can range from very mild to very severe.

Question 29

Meningoencephalocele

Answer 29

Bony defect (usually occipital bone) results in the meninges and brain tissue herniating outside the body wall

Question 30

Holoprosencephaly?

Answer 30

Loss of midline structures leads to malformations of brain and face. Mild case: only detected by pt having a single incisor tooth. Severe cases can result in fusion of cerebral hemispheres, eyes, and are not compatible with life

Question 31

Microcephaly?

Answer 31

Cranial vault is smaller than normal. Size of cranium depends on growth of the brain, so there is a defect in brain development. Intellectual disability in over half of cases

Question 32

Hydrocephaly?

Answer 32

Abnormal accumulation of CSF within ventricular system. Most cases due to aqueductal stenosis

Question 33

Schizencephaly?

Answer 33

Large cleft in cerebral hemispheres, sometimes causing loss of brain tissue. Neuron migration defects. Bilateral associated with speech and motor delays. Unilateral is associated with motor delays (weakness)

Question 34

Dandy-Walker syndrome?

Answer 34

Partial or complete absence of the cerebellar vermis. Enlargement of the 4th ventricle. A cyst remains. Pt will have motor and balance disturbances

Question 35

Lissencephaly?

Answer 35

Smooth brain. Defective neural migration. Severe neurological defects, can result in miscarriage

Question 36

Arnold-Chiari defect?

Answer 36

Cerebellum herniates through foramen magnum. Results in motor problems (balance problems, numbness). Associated with spina bifida cystica