Embryology Flashcards
what week does CNS development start?
week 3
what germ layer does the CNS come from?
ectoderm
neuroectoderm leads to what four things?
CNS neurons
oligodendroglia
astrocytes
ependymal cells
neural crest cells lead to what type of neurons? and what cell type?
PNS neurons and schwann cells
the mesoderm leads to what cell type in CNS?
microglia
what is the first step in neurulation?
neural plate invaginates and makes a neural groove
what happens to the neural groove in neurulation?
folds in and closes to become the neural tube
do neural crest cells lie ventral or dorsal to the neural tube?
dorsal
what week does neurulation end?
week 4
what are the last locations to close in neurulation?
cranial and caudal neuropores
what structure induces the ectoderm to start the neurulation procesS? what does this become?
notochord…becomes nucleus pulposus of the intervertebral discs
what does the neural tube lumen become? 2 things
ventricles of the brain and the central canal of spinal cord
name the three layers of the neural tube wall
ventricular
intermediate
marginal
what does the ventricular layer of the neural tube wall become?
ependymal cells..lining of ventricles
what does the intermediate layer of the neural tube wall become?
gray matter (neuron cell bodies)
what does the marginal layer of the neural tube wall become?
white matter (axon clusters)
is the dorsal region of the SC associated with the alar or basal plate?
alar plate
is the ventral region of the SC associated with the alar or basal plate?
basal plate
is the basal plate associated with the dorsal or ventral horn?
ventral horn
is the alar plate associated with the dorsal or ventral horn of the SC?
dorsal horn
is the dorsal region/dorsal horn of the SC associated with motor or sensory?
sensory
is the ventral region/ horn of the SC associated with motor or sensory?
motor
is the motor portion of the SC associated with the alar or basal plate?
basal plate
is the sensory portion of the SC associated with the alar or basal plate?
alar
the forebrain leads to what two structures
telencephalon and diencephalon
the telencephalon leads to what?
cerebrum
the diencephalon leads to what?
trick question…diencephalon
the diencephalon consists of what three things?
thalamus, hypothalamus and epithalamus
the midbrain leads to what?
mesencephalon
the mesencephalon leads to what?
midbrian
the hindbrain leads to what two structures?
metencephalon and myelencephalon
the metencephalon leads to what 2 structures?
pons and cerebellum
the myelencephalon leads to what?
medulla
how does the brainstem develop?
just like the SC…alar plate leads to afferent cranial nerves that is associated with sensation and the basal plate leads to efferent cranial nerves that is associated with motor
what is usual cause of NTD?
bone failure to close
what is the risk factor for NTD?
folic acid deficiency in mom
what is spina bifida occulta?
only tuft of hair or dimple comes through…no herniation
what is meningocele?
meninges but no neural tissue herniate through bony defect
what is myelomeningocele?
meninges and neural tissue herniate through bony defect
what is myeloschisis/rachischisis?
exposed unfused neural tissue without skin/meningeal covering
what is clinical prognosis of myeloschisis/rachischisis?
no function below the lesion
what is myeloschisis/rachischisis usually associated with?
anencephaly
what is anencephaly?
cranial/rostral neuropore does not close and forebrain does not form
what is holoprosencephaly?
failure of forebrain to divide into two hemispheres so you get one big one
what gene is associated with holoprosencephaly?
sonic hedgehog
what can be elevated in mom that signal a potential neural tube defect?
alpha fetoprotein
what structure are Chiari malformations associated with?
cerbellum
what is Chiari 1 malformation an issue with?
tonsils of cerebellum herniate into the foramen magnum of the SC
what is chiari 1 malformation associated with?
syringomyelia
what is chiari 2 malformation an issue with?
herniation of vermis and tonsil of cerebellum through foramen magnum of SC with aqueductal stenosis
the aqueductal stenosis in chiari 2 malformation can cause what? why?
hydrocephalus…because blocking leak from 3rd to fourth ventricle
what is chiari 2 malformation often associated with?
myelomeningocele
what is Dandy Walker malformation?
vermis agenesis in cerebellum
dilated fourth ventricle and hydrocephalus
what gets filled by the fourth ventricle in Dandy walker malformation?
posterior fossa
what is syringomyelia?
a tubular cavitation in the central canal of the SC
how does syringomyelia present?
2nd or 3rd decade with wasting/weakness of hand/forearm muscles and loss of reflex in arm
what is syringomyelia usually associated with?
chiari type 1 malformation
what else can cause syringomyelia?
tumor, traume, meningitis, hemorrhage
