cns Flashcards
CNS basics
CNS = brain + spinal cord
* protected by bony structures (vertebrae) + 3 layers membranes = meninges
* receive afferent from PNS, analyse, sompare w past, + integrate to gen motor output to PNS
brain regions
forebrain = cerebrum + diencephalon w pit gland, limbic sys + olfactory bulb
midbrain = midbrain
hindbrain = pons + medulla oblongata + cerebellum
cerebrum has longitudinal fissure => L + R hemispheres
spinal cord
out brain @ foramen magnum, down vertebral canal
* each spinal seg gives off pair segmental spinal nerves to supply diff region of bod
* at caudal end canal cord peters out + spinal nerves for caudal structures form cauda equine
timeline brain development
- dorsal ectoderm thickens form neural plate
- other development processes overlap + continue well into adulthood
neurulation
- notochord = cylinder mesodermal cells + secr chem signals inc prot sonic hedgehog induce formation neural plate
- chem signals also stim other mesodermal cells develop -> vertebral bods + intervertebral discs of spinal column (form protective structures)
- plate indented along midline = neural groove
- groove deepens + ectodermal walls thicken @ dorsal lips = neural folds
- folds fuse to close tube, starting cervical region + moving both rostral + caudal
- rostral/caudal neuropore = pt closed to (hole) - get smaller + smaller + close last
- dorsally either side superficial ectoderm proliferates -> cells -> pinch off + form neural crest
which parts from neurulation form what
CNS from neural tube
PNS from tube + neural crest
what happens after neurulation
rostral neural tube forms vesicles bc its hollow
* first 3 primary vesicles develop
* these differentiate into secondary vesicles
* these develop to adult brain structures
which mols control patterning which parts CNS
- patterning ventral structures controlled by sonic hedgehog prot from notochord
- patterning dorsal structures controlled morphogenetic prot signals frojm superficial ectoderm
names of diff vesicle structures + development path
all early in gestation
differential growth means diff outpockets form
brain flexures at vesicle stage
important to orient structures
cerebrospinal fluid is + why
bathes inside (w/in tube) + out (its in meninges) of CNS for nourishment, waste removal, protect brain
spina bifida occulta
incomplete rostral or caudal fusion of neural folds = tube open = vertebral arches can’t form + fuse = neural v close outside world
* caudally common tailless breeds
grey matter + white matter
grey = cell bodies, dendrites + synapses
white = axons - white bc of fat in myelin
glial cells
supporting cells in CNS
nuclei + tracts w/in contect CNS
nuclei = clusters of cell bodies in CNS (ganglia in PNS)
tracts = bundles of axins in CNS (nerves in PNS)
decussation of tracts
many CNS functions cross over bet 2 hemispheres cerebrum
== info from/output to R side bod handled by L side brain
cross section spinal cord vs cerebrum
spinal cord = grey matter inside, white out
cerebrum = white + basal nuclei in deep parts w grey formed over
corpus callosum
white matter tract connecting cerebrum hemispheres, allowing exchange info
corpus striatum
basal nuclei in cerebrum interwoven w white matter tracts = stripy appearance
* involved planning + executing (esp habitual) movements (motor function)
* input from motor cortex + integrate w other inputs (thalamus, limbic sys)
* important animals, e.g. birds, w/o developed cerebral cortex (instead of motor cortex)
lining neural tube
initially pseudostratified columnar then diffs 3 layers:
1. inner ventricular zone = germinal = ependymal = gen new cells (divide into)
2. mantle = neuroblasts migrated here + diff into neurones/glia (+ mitotic in interphase)
3. marginal = axons of neurones w cell bods in mantle = white matter
diagram cell types lining neural tube life cycle
lining -> ciliated to move CSF
surface cerebellum compared cerebrum
cerebellum = smaller folds tiss called folia (as opposed sulci/gyri)
important sulci/gyri to remember
- cruciate sulcus crosses longitudinal fissure at right angle w motor cortex controlling movement sat there
- sylvian gyrus involved in processing auditory info (looks like ear)
brain lobes
named after bone section sits under (ish)