Development of the Nervous System Flashcards
nervous system develops from what embryonic layer
ectoderm
Neural tube gives rise to——
Brain in greek
Brain in latin
CNS (brain + spinal cord
Greek-encephalon
Latin-Cerebrum
Notochord embryonic origin
mesodermal origin,
Notochord development induces formation of
neural plate ( neural tube + neural crest)
what is primary neuralation
the process by which d neural folds fuse
forming a neural
tube.
derivatives of neural crest cells
● Pseudounipolar ganglion cells of the spinal and
cranial nerve ganglia
● Schwann cells (which elaborate the myelin sheath)
● Multipolar ganglion cells of autonomic ganglia.
● Leptomeninges (the pia-arachnoid), which envelop
the brain and spinal cord 5. Chromaffin cells of the
suprarenal medulla (which elaborate epinephrine).
● Pigment cells (melanocytes)
● Odontoblasts (which elaborate predentin)
● Aorticopulmonary septum of the heart
● Parafollicular cells (calcitonin-producing C-cells)
● Skeletal and connective tissue components of the
pharyngeal arches
neural crest cell gives rise to the PNS which consists of
● Peripheral
nerves
● Sensory ganglia
● Autonomic
ganglia
The alar plate of the brainstem & spinal cord gives rise to —– neurons
sensory neurons
The basal plate of the brainstem & spinal cord gives rise to —– neurons
motor neurons
protein in amniotic fluid which indicates neural tube defect
alpha-fetoprotein
3 main vesicles from neural tube
Forebrain (prosencephalon)
Midbrain (mesencephalon)
Hindbrain (Rhombencephalon)
cavity of Telencephalon
(cerebral hemispheres)
lateral ventricles
5 vesicles
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
cavity of diencephalon (thalamus + optic vesicle)
Third ventricle
cavity of mesencephalon (Mid brain)
cerebral aqueduct
cavity of metencephalon (pons and cerebellum)
upper 4th ventricle
cavity of Myelencephalon (medulla)
Lower 4th ventricle
3 layers of the spinal cord
inner - ventricular layer
intermediate -mantle layer
outer- marginal layer
layer that forms the white matter
of the SC
marginal Layer
layer that forms the gray matter
of the Spinal cord
mantle layer
End of the spinal cord is
Conus medullaris
L3- Children
L1- Adult
Part of the brain derived from dorsal surface of alar plate
Cerebellum
Anterior neuropore gives rise to —–
Failure to close
Lamina terminalis
Anencephaly : partial or complete absence of the brain with associated
defects of the cranial vault and scalp.
Failure of posterior neuropore to close
spina bifida (myeloschisis)
Anterior neuropore closes by Day
Posterior neuropore close by Day
Period of primary gastrulation
25
27
18-28
Type of spina bifida,
there is no involvement of the
meninges or the underlying spinal
cord, and the overlying skin is
closed.
Spina bifida occulta ( defect of mesodermal origin)
Spina bifida aperta with protrusion
○ of either the meninges alone is ———
○ spinal cord together with the meninges Is ——-
Meningocele
Meningomyelocele
Protrusion of a sac from the cranium consisting of portions of
the meninges and CSF, glial tissue, and brain substance with or without the ventricles due to failure of anterior neuropore to close is
Encephalocele
-could be frontal or occipital encephalocele
HYdrocephalus
(excess accu. of CSF In subarachnoid space &ventricles) is commonly caused by stenosis of
Cerebral aqueduct
Dandy walker syndrome is Congenital absence of the —– and ——which through lack of communication with the remainder of the ventricular system,
can be one cause of hydrocephalus.
lateral apertures (of Luschka)
median aperture (of Magendie),
Clinical manifestations of Dandy walker syndrome
Dandy-Walker Syndrome:
● Dilated fourth ventricle,
● Water on the brain,
● Small vermis
What is arnold-chiari malformation
elongation and herniation of the cerebellar tonsils though the foramen magnum thereby blocking CSF flow
Failure of midline cleavage of embryonic forebrain
Holoprosencephaly
( most severe manifestation of fetal alcohol syndrome)
Defect in the occipital bone through which meninges, cerebellar tissue, and 4th ventricle may herniate
Cranium bifidum
Obstructive hydrocephalus is due to
- Dilated Lateral and III ventricles
- Constriction of the Cerebral Aqueduct
abnormal closure of anterior neuropore affecting the
midbrain, hindbrain and entire spinal region dev.
craniorachischisis,
Anencephaly with defects confined to the midbrain
meroanencephaly
Anencephaly with lesions extending into the hindbrain
Holoanencephaly
NTD teratogen
Signalling req. for closure
Retinoid
PCP Signalling
