Nervous System Embryology Flashcards
define the neural plate
thickened area of embryonic ectoderm overlying the notochord
what three things form from the neural plate?
neural folds
neural tube
neural crest cells
Neural crest cells form the
PNS and ANS
neural tube forms the
brain and spinal cord
when does neurulation happen, and what is it?
begins about week 4
fusion of neural folds that leaves two openings at each end
two openings of neural tube and when they close
Rostral neuropore (cranial) - closes at day 25
Caudal neuropore - closes at day 27
neural pore closure induces
vascular circulation in neural tube
cranial 2/3 of neural tube walls thicken and give rise to ______
caudal 1/3 of neural tube walls thicken and give rise to ______
brain
spinal cord
neural canal forms (2)
ventricular system of brain and central canal of spinal cord
zones of neuroepithelium
ventricular zone (ependymal layer)
marginal zone
ventricular zone gives rise to
all neurons and macroglial cells (astrocytes and oligodendrocytes)
marginal zone gives rise to
white matter
neuroepithelial cells differentiate to and form the ________ between marginal and ventricular zones
neuroblasts
intermediate zone
intermediate zone consists of glioblasts that differentiate to (3)
astroblasts –> astrocytes
oligodendroblasts –> oligodendrocytes
ependymal cells –> lining of central canal
In SC development, thickening of walls produces groove called __________ that separates the ______ and _______
sulcus limitans
alar plate (dorsal aspect)
basal plate (ventral aspect)
what is the alar plate
forms dorsal grey columns
- afferent nuclei - dorsal roots
what is the basal plate
forms ventral grey columns
- efferent nuclei - ventral roots
forms lateral grey columns
spinal ganglia from from
neural crest cells
define dorsal root ganglia
collection of cell bodies for afferent (sensory) neurons
primordial meninges from from
mesenchyme and NCC around neural tube
two layers of primordial meninges
dura mater - external layer
leptomeninges - internal layer made of NCC
leptomeninges differentiate to
arachnoid mater
pia mater
subarachnoid space
when does CSF form?
week 5
where does CSF circulate?
around brain and SC in subarachnoid space, spinal canal, and ventricles
when is spinal cord the entire length of the vertebral canal?
8 weeks
in newborns the spinal cord ends at (vertebrae) ____
in adults the spinal cord ends at ____
L2, L3
L1
extension of pia mater that anchors spinal cord so it doesn’t shrink up
filum terminale
spinal nerves for lower body from the
cauda equina
when does myelination happen and what gets myelinated first?
begins at end of fetal period and continues during first year after birth
motor roots first, then sensory
cells that myelinate axons of the CNS
oligodendrocytes (derived from neuroepithelial cells)
cells that myelinate axons of the PNS
Schwann cells (derived form NCC)
embryonic halves of neural arch fail to fuse in the median plane
L5 or S1 with dimple and/or tuft of hair
Spina Bifida Occulta
vertebrae over spinal cord fail to form, exposing the spinal cord
most severe neural tube defect
Spina Bifida Myeloschesis
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
Spina Bifida Cystica
three primary brain vesicles
Forebrain
Midbrain
Hindbrain
forebrain aka _______ which gives rise to _______ and _________
prosencephalon
- telencephalon -> cerebrum - diencephalon --> thalamus
midbrain gives rise to _____
mesencephalon –> midbrain
hindbrain aka ______ which gives rise to _____ and ________
rhombencephalon
- metencephalon --> pons, cerebellum - myelencephalon --> medulla oblongata
myelencephalon becomes the ______ with these neuroblasts (7)______
medulla oblongata
basal plate: GSE, SVE, GVE
alar plate: GVA, SVA, GSA, SSA
metencephalon becomes _____ and ________,
- cavity forms part of __________
cerebellum and pons
4th ventricle
in midbrain, neuroblasts migrate from alar plates into ______ to form:
_________ - visual reflex
_________ - auditory reflex
tectum
superior colliculi
inferior colliculi
in midbrain, neuroblasts migrate from basal plates to form
_________ - collection of nuclei
_________ - gray matter
tegmentum
substantia nigra
telencephalon develops from the _________
location:
prosencephalon
rostral part
what do telencephalic vesicles differentiate to?
primordia of cerebral hemispheres
cavity becomes lateral ventricles and third ventricle
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:
prosencephalon
thalamus
hypothalamus
epithalamus
pineal gland
The pituitary gland is from from these two growths:
up-growth from the ectodermal roof of the stomodeum (Rathke’s pouch, or adenohypophysis)
down-growth from the neuroectoderm (neurohypophysis)
neurohypophysis –> _________
adenohypophysis –> _________
posterior pituitary
anterior pituitary
why do the two lobes of the pituitary gland function differently?
they come from different embryologic origins
growth of tissue exceeds brain cavity, resulting in the formation of _____ and ______ that increase surface area
gyri and sulci
form all sensory cells of the PNS
NCC
describe sensory cells
ganglia located outside of the PNS and surrounded by satellite cells
dorsal nerve roots
form motor nerve fibers arranged in a bundle (ventral nerve root)
basal plates of developing SC
classification of cranial nerves based on embryological origin
Somatic efferent from basal plates of brain stem
nerves of pharyngeal arch
special sensory nerves
somatic efferent nerves from basal plates (5)
CN III - oculomotor CN IV - trochlear CN VI - abducens CN XI - spinal accessory CN XII - hypoglossal
nerves of the pharyngeal arches (4)
CN V - trigeminal
CN VII - facial
CN IX - glossopharyngeal
CN X - vagus
special sensory nerves (3)
CN I - olfactory
CN II - optic
CN VIII - vestibulocochlear
