Nervous System Embryology

Question 1

define the neural plate

Answer 1

thickened area of embryonic ectoderm overlying the notochord

Question 2

what three things form from the neural plate?

Answer 2

neural folds
neural tube
neural crest cells

Question 3

Neural crest cells form the

Answer 3

PNS and ANS

Question 4

neural tube forms the

Answer 4

brain and spinal cord

Question 5

when does neurulation happen, and what is it?

Answer 5

begins about week 4

fusion of neural folds that leaves two openings at each end

Question 6

two openings of neural tube and when they close

Answer 6

Rostral neuropore (cranial) - closes at day 25

Caudal neuropore - closes at day 27

Question 7

neural pore closure induces

Answer 7

vascular circulation in neural tube

Question 8

cranial 2/3 of neural tube walls thicken and give rise to ______

caudal 1/3 of neural tube walls thicken and give rise to ______

Answer 8

brain

spinal cord

Question 9

neural canal forms (2)

Answer 9

ventricular system of brain and central canal of spinal cord

Question 10

zones of neuroepithelium

Answer 10

ventricular zone (ependymal layer)

marginal zone

Question 11

ventricular zone gives rise to

Answer 11

all neurons and macroglial cells (astrocytes and oligodendrocytes)

Question 12

marginal zone gives rise to

Answer 12

white matter

Question 13

neuroepithelial cells differentiate to and form the ________ between marginal and ventricular zones

Answer 13

neuroblasts

intermediate zone

Question 14

intermediate zone consists of glioblasts that differentiate to (3)

Answer 14

astroblasts –> astrocytes
oligodendroblasts –> oligodendrocytes
ependymal cells –> lining of central canal

Question 15

In SC development, thickening of walls produces groove called __________ that separates the ______ and _______

Answer 15

sulcus limitans

alar plate (dorsal aspect)

basal plate (ventral aspect)

Question 16

what is the alar plate

Answer 16

forms dorsal grey columns

- afferent nuclei - dorsal roots

Question 17

what is the basal plate

Answer 17

forms ventral grey columns
- efferent nuclei - ventral roots
forms lateral grey columns

Question 18

spinal ganglia from from

Answer 18

neural crest cells

Question 19

define dorsal root ganglia

Answer 19

collection of cell bodies for afferent (sensory) neurons

Question 20

primordial meninges from from

Answer 20

mesenchyme and NCC around neural tube

Question 21

two layers of primordial meninges

Answer 21

dura mater - external layer

leptomeninges - internal layer made of NCC

Question 22

leptomeninges differentiate to

Answer 22

arachnoid mater
pia mater
subarachnoid space

Question 23

when does CSF form?

Answer 23

week 5

Question 24

where does CSF circulate?

Answer 24

around brain and SC in subarachnoid space, spinal canal, and ventricles

Question 25

when is spinal cord the entire length of the vertebral canal?

Answer 25

8 weeks

Question 26

in newborns the spinal cord ends at (vertebrae) ____ | in adults the spinal cord ends at ____

Answer 26

L2, L3 | L1

Question 27

extension of pia mater that anchors spinal cord so it doesn't shrink up

Answer 27

filum terminale

Question 28

spinal nerves for lower body from the

Answer 28

cauda equina

Question 29

when does myelination happen and what gets myelinated first?

Answer 29

begins at end of fetal period and continues during first year after birth motor roots first, then sensory

Question 30

cells that myelinate axons of the CNS

Answer 30

oligodendrocytes (derived from neuroepithelial cells)

Question 31

cells that myelinate axons of the PNS

Answer 31

Schwann cells (derived form NCC)

Question 32

embryonic halves of neural arch fail to fuse in the median plane L5 or S1 with dimple and/or tuft of hair

Answer 32

Spina Bifida Occulta

Question 33

vertebrae over spinal cord fail to form, exposing the spinal cord most severe neural tube defect

Answer 33

Spina Bifida Myeloschesis

Question 34

Protrusion of the spinal cord, meninges, or both through in a cyst-like sac due to defects of vertebral arch formation - with meningocele - with meningomyelocele

Answer 34

Spina Bifida Cystica

Question 35

three primary brain vesicles

Answer 35

Forebrain Midbrain Hindbrain

Question 36

forebrain aka _______ which gives rise to _______ and _________

Answer 36

prosencephalon - telencephalon -> cerebrum - diencephalon --> thalamus

Question 37

midbrain gives rise to _____

Answer 37

mesencephalon --> midbrain

Question 38

hindbrain aka ______ which gives rise to _____ and ________

Answer 38

rhombencephalon - metencephalon --> pons, cerebellum - myelencephalon --> medulla oblongata

Question 39

myelencephalon becomes the ______ with these neuroblasts (7)______

Answer 39

medulla oblongata basal plate: GSE, SVE, GVE alar plate: GVA, SVA, GSA, SSA

Question 40

metencephalon becomes _____ and ________, | - cavity forms part of __________

Answer 40

cerebellum and pons 4th ventricle

Question 41

in midbrain, neuroblasts migrate from alar plates into ______ to form: _________ - visual reflex _________ - auditory reflex

Answer 41

tectum superior colliculi inferior colliculi

Question 42

in midbrain, neuroblasts migrate from basal plates to form _________ - collection of nuclei _________ - gray matter

Answer 42

tegmentum substantia nigra

Question 43

telencephalon develops from the _________ | location:

Answer 43

prosencephalon rostral part

Question 44

what do telencephalic vesicles differentiate to?

Answer 44

primordia of cerebral hemispheres cavity becomes lateral ventricles and third ventricle

Question 45

diencephalon develops from the _________ Swellings from lateral walls of 3rd ventricle form (3): Median tissue from the caudal part of the roof of the diencephalon becomes:

Answer 45

prosencephalon thalamus hypothalamus epithalamus pineal gland

Question 46

The pituitary gland is from from these two growths:

Answer 46

up-growth from the ectodermal roof of the stomodeum (Rathke's pouch, or adenohypophysis) down-growth from the neuroectoderm (neurohypophysis)

Question 47

neurohypophysis --> _________ adenohypophysis --> _________

Answer 47

posterior pituitary anterior pituitary

Question 48

why do the two lobes of the pituitary gland function differently?

Answer 48

they come from different embryologic origins

Question 49

growth of tissue exceeds brain cavity, resulting in the formation of _____ and ______ that increase surface area

Answer 49

gyri and sulci

Question 50

form all sensory cells of the PNS

Answer 50

NCC

Question 51

describe sensory cells

Answer 51

ganglia located outside of the PNS and surrounded by satellite cells dorsal nerve roots

Question 52

form motor nerve fibers arranged in a bundle (ventral nerve root)

Answer 52

basal plates of developing SC

Question 53

classification of cranial nerves based on embryological origin

Answer 53

Somatic efferent from basal plates of brain stem nerves of pharyngeal arch special sensory nerves

Question 54

somatic efferent nerves from basal plates (5)

Answer 54

``` CN III - oculomotor CN IV - trochlear CN VI - abducens CN XI - spinal accessory CN XII - hypoglossal ```

Question 55

nerves of the pharyngeal arches (4)

Answer 55

CN V - trigeminal CN VII - facial CN IX - glossopharyngeal CN X - vagus

Question 56

special sensory nerves (3)

Answer 56

CN I - olfactory CN II - optic CN VIII - vestibulocochlear