Development of the Nervous System Flashcards
notochord induces thickening in the overlying ectoderm, forming the _____
neural plate
neural folds approach midline and fuse, forming ____ (forms dorsal to the notochord, along midsagittal axis)
neural tube
neural tube starts to close at about the ____ level, and progresses cranially and caudally
5th somite
cranial neuropore closes about day ___
25
caudal neuropore closes about day ___
27
_____ is a derivative of the neural crest cells
dorsal root ganglion
embryonic ectoderm will form the ____
epidermis
the neural tube (neuroectoderm) will form the _____
brain and spinal cord (CNS)
the neural canal (neural groove) will from the _____ and _____
ventricles of the brain; central canal of spinal cord
the neural crest will form:
- dorsal root/autonomic/CN ganglia
- bones of face (viscerocranium)
- melanocytes
- schwann cells
- leptomeninges (arachnoid and pia mater)
- adrenal medulla cells
the caudal end of the neural tube will form the ____ and the cranial end of the neural tube will form the ____
spinal cord; brain
the cells of the neural tube are _____
pseudostratified columnar neuroepithelium
the three membranes that envelop the brain and spinal cord
the meninges
dura mater embryonic origin
mesenchyme surrounding the neural tube
arachnoid mater embryonic origin
neural crest
pia mater embryonic origin
neural crest
arachnoid mater and pia mater are often called _____ because of their similar embryonic origin
leptomeninges
zones from luminal surface of the neural tube to the spinal meninges
ventricular zone or neuroepithelial zone –> intermediate zone or mantle zone –> marginal zone
the ____ is where you ahve true neuroblasts and true neurons developing, and will eventually become the gray matter of the spinal cord
intermediate or mantle zone
where glial cells are forming; will eventually become the white matter of the brain
marginal zone
on the dorsal aspect of the developing spinal cord, ____ develop within the mantle/intermediate layer
alar
the neurons within the mantle/intermediate layer have _____ function
afferent (sensory)
on ventral aspect of developing spinal cord, ____develop within the mantle/intermediate layer
basal
the neurons within the basal plates have ____ function
efferent (motor)
the alar plates develop into the ____
dorsal sensory horn
the basal plates develop into the _____
ventral motor horn
motor nerve fibers collect into _____
ventral nerve roots
_____ (sensory) originate outside the spinal cord (in the dorsal root ganglion) derived from _____
dorsal nerve roots; neural crest cells
dorsal nerve root processes grow into _____
dorsal horns of the spinal cord
distal processes of dorsal roots join ventral nerve roots to form a ____
spinal nerve
dorsal root fibers of a spinal nerve are ____
sensory
ventral root fibers of a spinal nerve are ____
motor
a spinal nerve contains both ____ and ____ fibers
sensory; motor
where would you perform a spinal tap or epidural?
L3
originally, embryonic spinal cord is the length of the _____, and spinal nerves exit vertebral column at their correct level of origin
vertebral canal
the ____ will lengthen faster than ____ so that in the adult, the spinal cord ends _____ vertebrae (______)
vertebral column; spinal cord; between L1 and L2; (conus medullaris)
brain development has same basic organization as spinal cord: distinct ____ and ____ plates
alar; basal
higher center in brain means there is accentuation of ____ and regression of _____
alar plates; basal plates
the brain develops from 3 primary vesicles:
- forebrain (prosencephalon)
- midbrain (mesencephalon)
- hindbrain (rhombencephalon
from 3 primary vesicles, the brain differentiates into ___ secondary vesicles
5
the forebrain differentiates into:
telecephalon and diencephalon
the midbrain differentiates into:
mesencephalon
the hindbrain differentiates into:
metencephalon and myelencephalon
adult derivatives of the telencephalon
walls- cerebral hemispheres
cavities- lateral ventricles
adult derivatives of the diencephalon
walls- thalami, etc.
cavities- third ventricle
adult derivatives of the midbrain
walls- midbrain
cavities- aqueduct
adult derivatives of the hindbrain
walls- medulla
cavities- lower part of fourth ventricle
in the myelencephalon, shift of medulla walls changes position of plates so that ____ will become medial to _____
basal plates (motor); alar plates (sensory)
in the myelencephalon, cells in ____cluster to form 3 bilateral cell columns with _____ nuclei
alar plate; afferent (sensory)
in the myelencephalon, cell bodies in the ____ cluster to form 3 bilateral cell columns with _____ nuclei
basal plate; efferent (motor)
in the mesencephalon, the basal plate contains two groups of ____; the marginal layer of basal plate enlarges to form _____
motor nuclei; crus cerebri
in the mesencephalon, the alar plate (sensory) is initially two ______
longitudinal elevations
in the mesencephalon, the alar plate divides into ___ and _____
superior; inferior colliculi
in the diencephalon, there are 3 pairs of swellings in the ____ wall of the ____
lateral; third ventricle
the caudal part of the roofplate becomes the _____
epithalamus
in the diencephalon, the alar plates form:
thalamus and hypothalamus
the telencephalon forms the two _____
cerebral hemispheres
in the telencephalon, the neural canal forms the two ____
lateral ventricles
the telencephalon surface grows rapidly to form the lobes as well as _____ (elevations) separated by ____ (deep grooves) and _____(shallow grooves)
gyri; fissues; sulci
embryonic origin of sympathetic NS
all ganglia as well as the sympathetic trunk originate from neural crest cells
embryonic origin of parasympathetic NS
postganglionic neurons derived from neural crest cells
myelinated axons in the PNS have series of ____ lined up along the axon, each having a wrapped coating of myelin insulating axon
Schwann cells
unmyelinated axons in the PNS are encased by _____; there is no wrapped coating of myelin surrounding axon
schwann cell cytoplasm
myelination in the PNS involves ____ (derived from neural crest cell
schwann cells
one schwann cell per one _____ of one axon
internodal segment
myelination in the CNS involves ____ derived from _____ of the spinal cord
oligodendrocytes; neuroepithelial cells
one oligodendrocyte can myelinate up to ____
50 axons
