development of the CNS Flashcards
early development of CNS DIAGRAM
there is ecto, then meso, then endoderm- forms skin/NS, skeletal muscle/heart/blood, and gut/liver/lungs respectively
neural plate folds to form neural fold, which then forms a neural canal on the walls of the neural canal is the neuroepithelium, and just outside is the neural crest, from where the peripheral NS develops
differentiation of neuroepithelium
neuroblasts are the origin of all neurons with cell bodies in CNS glioblasts form astrocytes (neural transmission, blood brain barrier) and oligodendrocytes (myelinating cells of CNS) (blasts are origin cells) ependymal cells line ventricles and central canal of spinal cord
differentiation of neural crest cells
sensory neurons of dorsal root ganglia (emerges from dorsal root) postganglionic autonomic neurons schwann cells non-neuronal cells eg melanocytes
proliferation of neuroepithelium DIAGRAM
lots of proliferation occurs from inside to outside ependymal layer lines ventricles, where division occurs- these cells then migrate to grey matter, and axons emerge at white matter
layers of neural tube DIAGRAM
unlike brain, grey matter at core also roof plate and floor plate
developing spinal cord DIAGRAM
neural crest cells are in dorsal root ganglion, where sensory neurons form in ventral/basal plate/grey matter is where motor neurons develop, and go to skeletal musce in dorsal/alar plate/grey matter are interneurons where sensory neurons go to
mature spinal cord DIAGRAM
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developing brainstem (DIAGRAM)
motor nuclei are more medial than sensory nuclei, and unlike spinal cord, neural tube is NOT closed
developing brain at 4 weeks
forebrain (cortex), midbrain (brainstem), hindbrain (cerebellum) and spinal cord
developing brain at 5 weeks
telecephalon (cortex) and diencephalon (thalamus/hypo) form, then midbrain, then pons and medulla
developing brain at 8 weeks DIAGRAM
hemispheres and ventricles start to develop- left ventricle in each hemisphere drain into 3rd ventricle aqueduct forms in midbrain, which drains into 4th ventricle, and cerebellum starting to develop (little brain)
flexures at 4 weeks DIAGRAM
cephalic, pontine (at pons) and cervical (where spinal cord starts) flexures these flexures then progress to form the different areas at 8 weeks
developing cortex DIAGRAM with layers
in the tencecephalon (developing cortex), lining the ventricles is the ependymal/ventricular doe, then subventricular (where division also occurs), then intermediate, then cortical plate and marginal zone radial glial cells act as a scaffold for the migration of neurons by the end 6 layers form in cortex
neural tube defects
two types, either ventrally or dorsally
anencephaly is when skull incomplete as anterior neuropore fails to close
craniorachichsis where brain and spinal cord both open= death
encephalocele is where meninges is herniated in brain
spina bifida is failure to close posterior neuropore
meningocele is where there is herniation of meninges in spinal cord
myelomeningocele is where the spinal cord is open
neural stem cells
degenerative diseases lead to shrinkage of the brain, even though we have stem cells in the hippocampus there are however not enough
lateral view of brain blood supply DIAGRAM
all the cortexes are supplied by middle cerebral artery, including motor cortex, APART FROM feet to waist
cranial nerves order DIAGRAM
1- olfactory
2- optic
3- oculomotor
4- trochlear
5- trigeminal
6- abducens
7- facial
8- vestibulocochlear
9- glossopharyngeal
10- vagus
11- accessory
12- hypoglossal
