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B2 Devo: Nervous System Development I
Terms in this set (74)
collection of cell bodies outside the CNS
collection of cell bodies within the CNS
motor fibers that extend below L1-L2 that extend inferiorly to exit at the appropriate spinal level
Motor neurons of the spinal cord are located in the ___________ horn. Their axons exit the cord through ___________ roots.
Brain consists of ___________ _________, ______________, ___________________, and _______________.
brain stem, cerebellum, diencephalon, telencephalon.
Brain stem consists of ___________, ______, and _____________
medulla, pons, and midbrain
Diencephalon consists of ____________, ______________, and _____________
thalamus, hypothalamus, and epithalamus
Telencephalon consists of the ____________ and ___________ __________.
Striatum and cerebral cortex
Transformation of surface ectoderm into the neural plate occurs during week __
Primary neurulation includes which events?
neural folds and midline neural groove form on neural plate in region of 4-6 somites
Closure of the neural tube proceeds bi-directionally; first closure on day ___ in the region of the ___ somite.
day 22, 5th somite
Cranial (rostral) neuropore closes by day ___-___
Caudal neuropore closes in a cranio-caudal direction by day ___-___
Caudal most portion of the neural tube is formed by secondary neurulation of the ___________ __________, not the neural plate.
Secondary neurulation is completed by week __
What is spina bifida?
birth defects of the spinal cord associated with failures in the fusion of the neural tube and vertebral arches
Major spina bifida defects are termed insignificant (______________) or major (_________________).
Occulta vs. Cystica
Defects in the closure of the rostral neuropore result in incomplete development of....
brain, calvaria, or face
severe rostral neural tube defect
portions of cranium fail to form --- forebrain, midbrain, and hindbrain fail to form
Spina bifida occulta
failure of fusion of vertebral arches
leads to small dimple with a tuft of hair
spinal cord in normal position but a meningeal sac protrudes through the defect
spinal cord and nerve roots protrude through the vertebral defect
most severe form of spina bifida
neural tube failed to fuse, resulting in a flattened neural mass directly exposed to amniotic fluid
1. Parasympathetic ganglia of CN III
2. Connective tissue around the eye
3. optic nerves
4. muscles of pupil and ciliary body
5. pia and arachnoid mater of occipital region
These are all derivatives of:
neural crest cells from cranial mesencephalon and caudal proencephalon
1. bones of the face and middle ear
2. dermis and smooth muscles of face
These are all derivatives of:
neural crest cells from mesencephalon and rhombencephalon
1. cranial nerve ganglia
2. all glial cells of the sensory ganglia of CN V-X
These are derivatives of:
Neural crest cells of rhombencephalon
1. peripheral sensory neurons (DRG)
2. Parasympathetic and sympathetic peripheral motor neurons
These are derivatives of:
Occipital and spinal neural crest cells
peripheral nerve tumors
tumor of adrenal medulla, autonomic ganglia
Caudal 1/3 of the neural plate forms the __________ _______
Lumen of the neural tube becomes reduced to a small ________ _______
neuroepithelial layer adjacent to central canal and contains precursor cells that give rise to all of the neurons and macroglia of the spinal cord
Primordial neurons (neuroblasts) migrate from the _____________ zone to form the _____________ zone
migrate from the ventricular zone to the intermediate zone
Marginal layer =
outer layer of the developing spinal cord
The marginal layer increases in mass due to....
addition of longitudinally running inter-segmental axons, long ascending axons from the gray matter, and long descending axons from supraspinal levels and incoming dorsal root sensory fibers
shallow longitudnal groove located in the lateral walls of the neural tube
separates the developing gray matter into dorsal alar plate and ventral basal plate
The sulcus limitans separates the developing gray matter into the dorsal ______ plate and ventral _______ plate.
Alar vs basal plates
neuronal cell bodies in the alar plate form nuclei that constitute the dorsal gray matter that receive and relay input from afferent neurons
cell bodies in basal plate form ventral gray matter of efferent neurons that extend the length of the cord. Axons of these neurons project motor fibers to skeletal muscle and form the ventral roots of spinal nerves
______ roof plate and _______ floor plate are formed by further development of spinal cord
dorsal roof plate vs. ventral floor plate
Describe the positional change of the spinal cord at week 8:
By week 8, the spinal cord extends the full length of the vertebral column. It ascends within the spinal canal to end at level L1-L2, resulting in formation of cauda equina
Motor nerve fibers begin to arise from the spinal cord at week __
How are nerve roots different from rami?
Dorsal and ventral roots emerge directly from spinal cord and coalesce outside the spinal cord to form spinal nerves. They then separate to form dorsal and ventral primary rami.
What secretes SHH first, and then what takes over secretion?
2. floor plate of neural tube
BMP is first secreted by ______ which then sets up a secondary center in the _______
First, ectoderm overlying the dorsal neural tube
Second, roof plate of the neural tube
The fate of neuroblasts in the developing neural tube is largely specified by the relative concentrations of the dual-opposing gradients of ______ and_______
SHH and BMPs
High BMP and low SHH gradient results in....
sensory neuron differentiation in the dorsal spinal cord
Low BMP and high SHH gradient results in....
motor neuron differentiation
By day ___: three primary vesicles of the brain are apparent. What are they?
During the _____ week, the prosencephalon and rhomboencephalon each sub-divide, contributing to the 5 secondary brain vesicles
The prosencephalon becomes the ____________ and the ____________
telencephalon and diencephalon
The rhomboencephalon becomes the
metencephalon and myelencephalon
Each "cephalon" becomes a ventricle. Which become which
telencephalon --> lateral ventricle
diencephalon --> third ventricle
mesencephalon --> aqueduct of Sylvius
Rhomboencephalon --> fourth ventricle
forms between rhombencephalon and spinal cord during week 5 - develops through week 8 - but does not persist in adult
forms at level of future midbrain and persist in adult as a bend between brainstem and forebrain
forms between metencephalon and myelencephalon during week 5 -- does not persist in adult but plays important role in development of cererbellum and pons
A pair of DRG develops at every spinal segment except at 1st ________, and 2nd and 3rd __________
2nd and 3rd coccygeal
Postganglionic parasympathetic neurons that innervate the viscera (e.g. heart, stomach, and bladder) are derived from neural crest cells originating from the __________ - ___________ region of the neural tube
Parasympathetic ganglion cells to the most inferior portion of the gut have dual origins: _______ - ______ neural crest and __________ neural crest.
occipito-cervical and sacral
Sympathetic chain ganglia are developed by neural crest cells. On each side, they become interconnected by longitudnal fibers. In the cervical region, there are ___ ganglia. In the coccygeal region, ___ ganglia is formed
3 in cervical region
1 in coccygeal region
After the chain ganglia are formed, neurons in the __________ horn send axons out through the ventral root and __________ communicating ramus to synapse inn the sympathetic ganglion at the same spinal level.
lateral horn, white communicating ramus
The layer of proliferating cells that line the central canal of the neural tube is called the __________ layer
first cells produced by ventricular layer -- eventually migrate to form the mantle layer
Neuroblasts migrate from the ventricular layer to form the __________ layer
Processes extend from the mantle layer to form a third layer:
The marginal zone contains (or lacks) ___________ and becomes the ________ matter
contains no cell bodies, becomes the white
differentiate from the epithelial lining of the neural canal
form the astrocytes and oligodendrocytes
Ependymal cell lining
neuroepithelial layer differentiates to form the ependymal cell lining of the ventricles and central canal of the spinal cord
How do neuroblasts form?
extend processes and form bipolar neuroblasts -- one process becomes primitive axon and other the primitive dendrite
Once the neuroblast differentiates and forms the primitive axon and primitive dendrite, it loses its ability to
Schwann cells myelinate in the _______
oligodendrocytes myelinate in the ______
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