Neural Development Flashcards
Describe how the neural tube develops
- notochord (mesoderm) induces overlying ectoderm to differentiate into the neural plate
- neural plate widens to form neural groove and folds (lateral edges)
- neural folds join to form the neural tube (lumen - ventricular system and central canal)
- dorsal cells differentiate into neural crest cells
- somites (mesoderm) alongside the tube will later becomes muscle, vertebrae, and dermis
anterior neuropore (what does it become, failure to close?)
becomes lamina terminalis; brain
leads to upper NTDs (anencephaly)
posterior neuropore (what does it become, failure to close?)
becomes spinal cord lower NTDs (spina bifida)
neurocristopathy
malformation of neural crest cells
schwannoma
- benign tumor of schwann cells
- encapsulated
- tinnitus, hearing loss
- frequently located near vestibular nerve
neurofibromatosis type 1
- autosomal dominant
- mutation in NF1 gene => protein neurofibromin => downregulates p21 oncoprotein
- multiple neural tumors, skin lesions
where do the optic vesicles arise from?
lateral extensions of diencephalon
- optic stalk connected to forebrain
- interaction with overlying ectoderm forms non-neural structures (lens, cornea)
forebrain vesicles
prosencephalon
=> telencephalon
=> diencephalon
midbrain vesicles
mesencephalon
=> mesencephalon
hindbrain vesicles
rhombencephalon
=> metencephalon
=> myelenephalon
telencephalon
regions - cerebral cortex - basal ganglia - amygdala - hippocampus => lateral ventricle
diencephalon
Regions -thalamus -hypothalamus -pituitary -pineal => 3rd ventricle
mesencephalon
Regions
- midbrain
=> cerebral aqueduct
metencephalon
regions
- pons
-cerebellum
=> 4th ventricle
myelencephalon
Regions - medulla
=> central canal
alar plate
-sensory
-dorsolateral
-receives axons from DRG
=> dorsal horn
functional components located in alar plate
GSA - sensory input
GVA - input from smooth muscles and glands
(SVA, SSA)
basal plate
- ventrolateral
- projections motor neurons => ventral horn
functional components of basal plate
GSE - motor output to skeletal muscles
GVE - autonomic control of smooth muscles and glnds
SVE
sulcus limitans
longitudinal groove
extends from spinal cord to rostral midbrain
caudal eminence
creates sacral and coccygeal segments of spinal cord
when and where does myelination arise
- month 4 => 2 years of age (spinal cord) => 30 years (brain)
- arises in ventral roots
spinal cord positions
conus medullaris:
- L3 at birth
- L1/L2 in adults
cauda equina - dorsal/ventral roots; below the conus medullaris
filum terminale - anchors spinal cord to coccyx
development of the brainstem
- canal expands to form 4th ventricle
- alar plate is pushed lateral to basal plate
- mesenchymal cells of the 4th ventricle attach to ependymal cells => pia mater
development of the medulla
- choroid plexus = off the roof
- foramen of luschka (lateral)
- foramen of magendie (median)
pyramids (ventral) - STT/SCT
spina bifida (meyloschisis) (general)
- vertebral arches fail to form
- lumbosacral more common
- folic acid
spina bifida occluta
- no neural tissue involved (sac is filled with CSF)
- dimples, tufts of hair
- least severe
- spinous process does not form
- spinal cord still intact
spina bifida cystica
- more severe
- with meningocyele (meninges protrude, spinal cord intact)
- with meningomyelocele (meninges and spinal cord protrude)
spina bifida with rachischisis
- posterior neuropore doesn’t close (week 4)
- neural tissue becomes necrotic and fails to develop
- diagnosed by detected elevated alpha-fetoprotein
cranium bifida (general)
- skull fails to form
- typically occipital plate
- folic acid
cranium bifida with meningocele
- meninges protrude (sac of CSF)
cranium bifida with meningoencephalocele
- meninges and brain tissue protrude
cranium bifida with meningohydroencephalocele
- meninges, brain, ventricle protrude
anencephaly
- severe upper NTD
- failure of brain to develop
- failure to thrive
hydrocephalus/dandy-walker syndrome
- CSF accumulates in lateral ventricle (stenosis of cerebral aqueduct)
- failure of foramens Luschka and Magendie to form => enlarged 4th ventricle
arnold-chiari malformation
caudal displacement of cerebellum through foramen magnum
- stretches cranial nerves 9-11
- difficulty swallowing
- spastic dysphonia
- diminished gag reflex
- apnea
- vocal cord paralysis
microcephaly
- small cranial vault
- lack of brain development
- impaired mental
