Development of the Nervous System

Question 1

Where does primary neurulation extend from?

Answer 1

Brain to the lumbar spinal cord

Question 2

What is the caudal eminence?

Answer 2

The caudal eminence induces the creation of the sacral and coccygeal parts of the spinal cord. It is part of secondary neurulation.

Question 3

Almost all cells of the NS come from neuroepithelium (neural tube), except for:

Answer 3

Microglia, which are developed monocytes from mesenchyme.

Question 4

Where do the brain vesicles begin to form?

Answer 4

Above the 4th somites

Question 5

3 brain vesicles

Answer 5

Prosencephalon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain

Question 6

When does the forebrain and hindbrain divide?

Answer 6

Wk 5

Question 7

What does the prosencephalon divide into?

Answer 7

Telencephalon and diencephalon

Question 8

What does the rhombencephalon divide into?

Answer 8

Metencephalon and myelencephalon

Question 9

Cervical flexure demarcates:

Answer 9

Demarcates the hindbrain from SC

Question 10

Pontine flexure demarcates:

Answer 10

Divides the hindbrain into metencephalon and myelencephalon.

Question 11

Cephalic flexure demarcates:

Answer 11

Bend between midbrian and forebrain

Question 12

What develops from weeks 6-32? (2)

Answer 12

Basal ganglion

Cortical structure

Question 13

Components of telencephalon (6)

Answer 13

Cerebral cortex
Subcortical white matter
Olfactory bulb and tract
Basal ganglia
Amygdala
Hippocampus

Question 14

Components of diencephalon (4)

Answer 14

Thalamus
Hypothalamus
Epithalamus
Eyes (CN II)

Question 15

Holoprosencephaly

Answer 15

Results from incomplete separation of cerebral hemispheres.

Many facial abnormalities can happen.

Question 16

Causes of Holoprosencephaly (3)

Answer 16

Genetic
Maternal diabetes
Teratogens

Question 17

What are the sources of the anterior and posterior lobes of the pituitary?

Answer 17

Anterior: first arch ectoderm
Posterior: neuroectoderm

Question 18

What part of the neural tube will become the SC?

Answer 18

Caudal to the 4th somites

Question 19

What is the sulcus limitans?

Answer 19

It separates the alar and basal plates within the SC

Question 20

Zones of the spinal cord

Answer 20

Ventricular zone (stem cell layer)
Intermediate zone (grey matter)
Marginal zone (white matter)

Question 21

Nerve fibers from the basal plate (3)

Answer 21

Motor to skeletal muscle and preganglionic ANS:
GSE
SVE
GVE

Question 22

Nerve fibers from the alar plate (4)

Answer 22

Sensory within CNS:
GVA
SVA
GSA
SSA

Question 23

Syringomyelia is:

What is it associated with?

Answer 23

Fluid filled cavity develops within the SC.

Hydrocephalus.

Question 24

What is deformed in Chiari malformations?

Answer 24

Deformity of the hindbrain

Question 25

Chiari type I

Answer 25

Herniation of cerebellar tonsils thru foramen magnum. | Often can be asymptomatic, but can have sx that align with problems in lower CNs.

Question 26

Chiari type II

Answer 26

Herniation of cerebellar tonsils and medulla thru foramen magnum. Hydrocephalus. Lower CN problems.

Question 27

Dandy Walker Malformation (Cyst)

Answer 27

Large posterior fossa cyst continuous with 4th ventricle. Hypoplasia of cerebellum. Atresia of foramina of Luschka and Magendie.

Question 28

Hydranencephaly

Answer 28

Absence of cerebral hemisphere, but brainstem intact. Excessive head growth after birth. Little/no cognitive development.

Question 29

Cytodifferentiation of cerebrum (lamina I-VI, superficial to deep)

Answer 29

Lamina I - mainly dendrites. Laminae II-III - mainly neurons. Laminae IV - receives inputs from thalamus. Lamina V - projects into structures like the brainstem, SC and basal ganglia. Lamina VI - projects primarily into the thalamus.

Question 30

Lissencephaly

Answer 30

AKA smooth brain. Problem with neuronal migration during wks 12-24. Child may have apnea, poor feeding or abnormal muscle tone.

Question 31

Microcephaly

Answer 31

Sign, not a dx. Can be from lack of brain development or injury to previously normal developing brain. Can be caused by genetics, infection, brain injury, etc.

Question 32

Cortical layers are laid down:

Answer 32

Inside out (deep to superficial)

Question 33

How is cerebellum developed?

Answer 33

Dorsal parts of alar plates --> cerebellar swellings --> project into 4th ventricle and fuse

Question 34

Position of SC in adult and infants:

Answer 34

Adults: L1-L2 Infants: L2-L3

Question 35

Neural crest cells give rise to:

Answer 35

Neurons on DRG Sensory ganglia of cranial nerves Schwann cells Smpathetic ganglia

Question 36

CNS myelination

Answer 36

Starts in lower brainstem with the older tracts first. | Done by oligodendrocytes. Begins 6 mo to puberty.

Question 37

PNS myelination

Answer 37

Motor roots before sensory roots. Schwann cells. Begins 4th mo.

Question 38

Spina bifida occulta Meningocele Meningomyelocele Myelocele

Answer 38

Spina bifida occulta: imcomplete closure of vertebra. Meningocele: protrusion of meninges. Meningomyelocele: protrusion of the meninges and can contain SC. Myelocele: SC is open to the outside.

Question 39

Anencephaly

Answer 39

Top of the head is exposed