Embryology of the Nervous System

Question 1

blastocyst

Answer 1

hollow sphere of cells with an inner cell mass that implants into the uterus

Question 2

trophoblast

Answer 2

outer layer of cells that develops into extraembryonic membranes

Question 3

inner cell mass

Answer 3

cell mass that becomes the fetus

Question 4

embryonic disc

Answer 4

hypoblast + epiblast (becomes 3 germ layers)

Question 5

gastrula

Answer 5

embryo with three distinct germ layers derived from epiblast

Question 6

ectoderm

Answer 6

becomes nervous system
(and hair, skin, nails)

Question 7

mesoderm

Answer 7

becomes vertebral column
(and skeletal/muscle structures, circulatory system)

Question 8

primitive streak

Answer 8

proliferation of cells that forms a ridge from caudal –> cranial in the embryonic disc

defines R/L and cranial/caudal

Question 9

notochord

Answer 9

mesoderm that migrates rostrally from primitive streak to form a rod shaped aggregate of cells

function: induce neurulation to form head process and somites

eventually becomes nucleus pulpous of IVDs

Question 10

neurulation

Answer 10

notochord - induced transformation of ectoderm into nervous tissue to form the CNS

Question 11

neural plate

Answer 11

neuroectoderm
ectodermal layer above the notochord that thickens and flattens

Question 12

neural groove

Answer 12

cells in the neural plate divide until it folds to form a groove

Question 13

neural crest cells

Answer 13

dorsal-lateral cells along neural tube that become PNS structures

Question 14

neural tube

Answer 14

fusion of neural groove to form a tube that becomes the basis of the CNS/PNS

Question 15

where does CNS development start

Answer 15

brainstem

brain: caudal –> cranial
spinal cord: cranial –> caudal

Question 16

germinal layer of neural tube

Answer 16

innermost layer of neuroepithelial cells that are actively dividing

Question 17

mantle layer of neural tube

Answer 17

layer of differentiated neuroepithelial cells into neuroblasts/glioblasts

forms the gray matter
spinal cord: inside
brain: outside

Question 18

marginal layer of neural tube

Answer 18

layer of myelinated axons from neurons in the mantle layer

forms the white matter
spinal cord: outside
brain: inside

Question 19

are microglia from the neuroectoderm

Answer 19

no

Question 20

sulcus limitans

Answer 20

bilateral indent forming a longitudinal groove

creates dorsal/ventral

Question 21

roof plate

Answer 21

dorsal white matter of neural tube (sensory)

Question 22

alar plate

Answer 22

dorsal gray matter of neural tube (sensory)

Question 23

basal plate

Answer 23

ventral gray matter of neural tube (motor)

Question 24

floor plate

Answer 24

ventral white matter of neural tube (motor)

Question 25

is dorsal sensory or motor

Answer 25

sensory

Question 26

is ventral sensory or motor

Answer 26

motor

Question 27

spinal dysraphism

Answer 27

neural tube defect causing abnormal development of the spinal cord

Question 28

spina bifida

Answer 28

spinal dysraphism caused by failure of neural tube closure results in part of the spine being exposed (meninges, spinal cord)

Question 29

IVD disease

Answer 29

disc disease often associated with FGF4 gene mutations causing increased FGF production during development

Question 30

causes of congenital vertebral abnormalities

Answer 30

1. failure of formation (notochord persists, failure of ossification/vascularization) 2. failure of somite segmentation or both

Question 31

hemivertebrae

Answer 31

half vertebrae; caused by failure of formation of part of the vertebral body - triangular shaped - occurs in screw tailed dogs

Question 32

butterfly vertebrae

Answer 32

dorsal-ventral cleft forms in vertebrae due to persisting notochord - occurs in screw tailed dogs

Question 33

block vertebrae

Answer 33

fusion of vertebrae caused by failure of segmentation

Question 34

spinal cord funiculi

Answer 34

bundles of nerve fibers formed by the dorsal and ventral roots of the spinal cord

Question 35

cephalization

Answer 35

concentration of neural tissue at the rostral part of a developing organism

Question 36

rhombencephalon

Answer 36

metencephalon + myelencephalon

Question 37

metencephalon

Answer 37

pons + cerebellum

Question 38

myelencephalon

Answer 38

medulla

Question 39

mesencephalon

Answer 39

midbrain; tectum + tegmentum

Question 40

prosencephalon

Answer 40

telencephalon + diencephalon

Question 41

telencephalon

Answer 41

cerebral cortex, basal nuclei, limbic system, rhinencephalon

Question 42

diencephalon

Answer 42

thalamus + hypothalamus

Question 43

pharyngeal arches

Answer 43

outpouchings of mesoderm that contain: - cranial nerves - special visceral muscle - blood supply, cartilage

Question 44

special visceral muscle

Answer 44

muscle NOT derived from somites - muscles of mastication - muscles of facial expression - stylopharyngeus - pharyngeal, laryngeal, cricoid, and esophagus muscles

Question 45

special visceral efferents

Answer 45

nerve fibers within certain cranial nerves that innervated special visceral muscle - CN V - muscles of mastication - CN VII - muscles of facial expression - CN IX - stylopharyngeus - CN X/XI - pharyngeal, laryngeal, cricothyroid, and esophagus

Question 46

somite derived muscles

Answer 46

extraocular muscles, muscles of the tongue

Question 47

general somatic efferents

Answer 47

innervate somite derived muscle - CN III, IV, VI (EO muscles) - CN XII (tongue)

Question 48

formation of medulla

Answer 48

1. roof plate stretches to form 4th ventricle 2. sulcus limitans forms dorsolateral and ventromedial segments in neural tube

Question 49

alar plate of medulla

Answer 49

dorsolateral; contains sensory neurons

Question 50

basal plate of medulla

Answer 50

ventromedial; contains motor neurons

Question 51

what do the cerebral hemispheres develop from

Answer 51

alar plate only

Question 52

paleopallium

Answer 52

rhinencephalon; the "smell brain" - olfactory bulbs - olfactory tracts - piriform lobe - hippocampus

Question 53

archipallium

Answer 53

limbic system forms the border of the cortex functions in behavior, emotion, memory, and olfaction - also includes hippocampus

Question 54

neopallium

Answer 54

initiates movement; only present in higher animals - cortical surface - basal nuclei - projection/association/commissural fibers