SFP: neurodevelopment

Question 1

When does the neural tube form?

Answer 1

Week 3

Question 2

What is neurulation?

Answer 2

The ectoderm differentiates into the neural plate, which then bends and fuses to form the neural crest. The neural tube also forms.

Question 3

What happens to the notochord during neurulation?

Answer 3

It disintegrates.

Question 4

What are neuroepithelial cells derived from?

Answer 4

The neural tube.

Question 5

What do neuroepithelial cells give rise to?

Answer 5

CNS structures.

Question 6

What do mesenchymal cells give rise to?

Answer 6

Microglia.

Question 7

What do neural crest cells give rise to?

Answer 7

PNS structures.

Question 8

What structure gives rise to pia and arachnoid?

Answer 8

Neural crest cells.

Question 9

What structure gives rise to the SNS and PNS postganglionic neurons?

Answer 9

Neural crest cells.

Question 10

What are the layers of the developing spinal cord?

Answer 10

Ependymal, mantle layer, and marginal layer.

Question 11

Describe the ependymal layer of the spinal cord.

Answer 11

Innermost layer with ependymal cells that line the central canal to form a germinal layer. This will become the ependymal lining and epithelium of the choroid plexus.

Question 12

Describe the mantle layer.

Answer 12

Neuroblasts migrate to form gray matter of the spinal cord.

Question 13

Describe the marginal layer.

Answer 13

Outermost layer that contains processes of neurons from the mantle layer. Basically, the white matter.

Question 14

Describe generally how the outer cell layers of the cerebellum and cerebral hemispheres are formed.

Answer 14

Neuroblasts migrate from the ependymal zone to form the layers.

Question 15

Briefly describe the neural tube organization.

Answer 15

Sulcus limitans separates the tube into dorsal and ventral sections. The dorsal section is the alar plate, and the ventral is the basal plate.

Question 16

Describe the alar plate.

Answer 16

Dorsal portion of the neural tube that gives rise to sensory cell bodies in the dorsal horn and interneurons.

Question 17

Describe the basal plate.

Answer 17

Ventral portion of the neural tube that gives rise to somatic and autonomic motor neurons and the ventral horn.

Question 18

What gives rise to dorsal root ganglion cells?

Answer 18

Neural crest cells.

Question 19

Describe what happens with developing axons in the spinal cord.

Answer 19

Cells grow processes to their targets via ventral or dorsal roots, depending on the cell type and what the target is.

Question 20

Describe the length of the spinal cord over time.

Answer 20

It’s pretty much full length when we’re born and occupies the full vertebral column. The spinal cord doesn’t really grow past birth, but we get taller. This is why it ends around L1/L2.

Question 21

Where does the dural sac terminate?

Answer 21

S1/S2.

Question 22

Where does the arachnoid terminate?

Answer 22

S1/S2 with the dural sac.

Question 23

Where does the pia terminate?

Answer 23

At the conus medullaris.

Question 24

What does the prosencephalon give rise to?

Answer 24

The telencephalon (cerebrum) and diencephalon (hypothalamus and thalamus).

Question 25

What will the telencephalon give rise to?

Answer 25

Forebrain structures like the cerebrum, olfactory cortex, hippocampus, basal ganglia, lateral and 3rd ventricles.

Question 26

What does the diencephalon give rise to?

Answer 26

Forebrain structures like the thalamus, hypothalamus, optic nerves, mamillary bodies, 3rd ventricle.

Question 27

What does the mesencephalon give rise to?

Answer 27

The midbrain and its structures.

Question 28

What does the rhombencephalon give rise to?

Answer 28

Metencephalon (pons) and myelencephalon (cerebellum).

Question 29

What does the metencephalon give rise to?

Answer 29

Hindbrain structures like the pons and cerebellum.

Question 30

What does the myelencephalon give rise to?

Answer 30

Hindbrain structures like the medulla.

Question 31

What differentiates between months 6 and 9 in the brain?

Answer 31

Sulci, gyri, basal ganglia, limbic structures, olfactory.

Question 32

Where is the insula located?

Answer 32

Between the frontal, temporal, and parietal lobes.

Question 33

Compare the spinal cord and brain during development.

Answer 33

They both have large ventricles, dorsal/ventral regions. Grey matter columns extend into the brain, forming a semi-continuous structure.

Question 34

Describe how grey matter nuclei in the brain form.

Answer 34

Gray matter of the SC grows into the brain during development and will eventually form nuclei.

Question 35

Compare the spinal cord and brain once they’re mature.

Answer 35

Ventral/dorsal symmetry in the brain is lost, and nuclei form as opposed to columns. There is also a reduced ventricular system.

Question 36

What is spina bifida?

Answer 36

A neural tube defect where the tube does not close completely, allowing parts of the nervous system to grow outside the designated area.

Question 37

Describe myeloschisis.

Answer 37

The spinal cord is exposed on the surface, causing severe functional deficits. This is a form of spina bifida.

Question 38

Describe spina bifida occulta.

Answer 38

Normal spinal cord function, but not complete closure of the canal. There may be a fat pad or patch of hair over the spot.

Question 39

What is meningocele?

Answer 39

Spinal cord is normal, but there is a swelling of meninges filled with CSF in the area where the canal did not fully close.

Question 40

What is meningomyelocele?

Answer 40

Swelling of the meninges filled with CSF that contains the spinal cord in the defect.

Question 41

What is encephalocele?

Answer 41

Midline cranial bones fail to ossify, causing meninges to project through the defect with or without brain tissue.

Question 42

What is anencephaly?

Answer 42

An extreme neural tube defect where the anterior neuropore does not close, causing absence of most of the brain.

Question 43

What is the most common neural tube defect in stillborns?

Answer 43

Anencephaly.

Question 44

What is an Arnold-Chiari malformation?

Answer 44

Parts of the cerebellum and medulla herniate through the foramen magnum (closure at base of the skull), blocking flow of CSF. Impacts on function vary from case to case.