Neurobiology Theme 1 Flashcards
what are the basic divisions of the nervous system
central, peripheral & enteric
enteric ns
digestive tract
sympathetic ns
flight or fight response
parasympathetic ns
rest and digest, saliva hormone and acid production
grey matter
interprets signal
astroglia and microglia
white matter
transmits signal
myelinated axons
oligodendroglia
microglia
ipsilateral
same side
contralateral
opposite side
ascending
towards brain
descending
away from brain
afferent
sensory fibres going upi
efferent
motor fibres
function frontal lobe
problem solving
function parietal lobe
interprets signal (taste, smell, hearing, touch)
function occipital lobe
vision and visual perception
function of temporal lobe
memory
function of a-beta fibres in the teeth
respond to noxious stimuli with short sharp pain
what are c-fibres responsible for
unmyelinated (slow) dull, throbbing ache or burning pain, lasts long
what nerves involved involved when local anaesthesia is given
long buccal
inferior alveolar
lingual
what is bells palsy
sudden paralysis of facial muscles
unilateral
what nerves does freys syndrome affect
affects same parasympathetic nerves that stimulate parotid gland
what is peripheral sensation
when inflamed there is increased responsiveness (tooth aches) and stimulus of nociceptors more persistent and intense
what is central sensation
if second order neurones receive prolonged stimulus of nociceptive input it may become sensitised
what is neuralgia
damage to the nerve itself, short sharp pain
what is trigeminal neuralgia
affects CNV, short sharp pain similar to electrical shock. usually unilateral and isolated to one division of V
what is atypical pain
persistent facial pain that does not fulfil any other diagnosis
what is localised non odontogenic pain
non tooth pain, must be present for 3 months or more than 8hrs a day. can occur following extraction even though nerve/tooth is gone
what is the function of a delta fibres
respond to noxious stimuli with short sharp pain
what is intravenous sedation
midazolam, caused central nervous depression reducing anxiety and respiratory and heart rate
what is inhalation sedation
nitrous sedation, produces euphoric and anxiolytic effect and small amount of analgesia
what are astrocytes
glial cells in the brain and spinal cord
physical constituent of the blood brain barrier
what are microglial cells
immune cells of the cns, proliferate and migrate to the site of injury (phagocytic role)
what oligodendrocytes
type of glial cell that provides support and insulation to axons in the cns. main role is the production of the myelin sheath
what is the neocortex
newest cortex, including primary sensory cortex, primary motor cortex, and association cortex
what are the neuroglia cell type
predominant cell types within the ns but not directly involved in information processing
provide appropriate structural matrix and chemical environment for neurones
what is the cerebellum
large structure of the hindbrain that controls fine motor skills. it remembers complex motor tasks. operates at an entirely unconscious level
what 3 parts is the cerebellum split into
inferior, middle and superior cerebellar peduncles
what is the function of the peduncles
they carry nerve fibres between the medulla, pons and midbrain, respectively, and the cerebellum
where are the superior and inferior colliculi located
dorsal surface of the midbrain
what does the cerebellum consist of
outer layer of grey matter
cerebellar cortex
folia (parallel folds)
what does the brainstem consist of
midbrain pons medulla
what are the sulci on the brain
alleys/folds
whats are the gyri on the brain
humps
functional area of the frontal lobe
precentral gyrus- this contains the primary motor cortex which is the highest level in the brain for the control of movement
functional area of the parietal lobe
post central gyrus/primary somatosensory cortex- site of termination of pathways carrying modalities of touch, pressure, pain and temp from opposite side of body
functional area of the occipital lobe
visual cortex- in gyri above and below calcarine sulcus
functional area of the temporal lobe
auditory cortex/superior temporal gyrus- localised to the superior temporal gyrus
functional area of the limbic lobe
cingulate gyrus
what does the frontal gyri separate
runs front to back, divides into 3 separate gyri (sup, middle, inf) and then into precentral and post central gyrus
what is the location and function of the angular gyrus
region of the brain in the parietal lobe responsible for language, number processing, spatial cognition, memory retrieval, attention
what is location of central sulcus
first major sulcus running top to bottom from the longitudinal to lateral fissure
what is the location and function of parieto-occipital sulcus
medial surface of brain, separates parietal and occipital lobes
what is the location of pre-central sulcus
divides the pre-central gyrus from the rest of the frontal gyri
function of primary cortex
regions involved directly with motor/sensory input (movement or sensation)
function of association cortex
deal with more complex aspects of sensory and motor functions, higher order processing areas
function of thalamus
relays messages between lower brain centres and cerebral cortex
function of hypothalamus
brain region controlling the pituitary gland (homeostasis, appetite, releasing hormones etc.)
function of pituitary gland
releases hormones into the blood stream
function of corpus callosum
connects two hemispheres
functional of longitudinal fissure
separates the 2 hemispheres which reaches the corpus callosum
what are the 3 germ cell layers that become established by the 2nd week of human embryonic development
ectoderm, mesoderm and endoderm
what does the ectoderm give rise to
skin and nervous system
what does the endoderm give rise to
alimentary, respiratory and genitourinary tracts
what is neuralation
process of formation of hte embryonic nervous system
what occurs during the 3rd week of embryonic development
dorsal midline ectoderm undergoes thickening to form the neural plate
how are neural folds formed
when the lateral margins of the neural plate become elevated on either side of the neural groove formed in the centre
how is the neural tube formed
the neural folds fuse together sealing neural groove
how is the neural crest formed
cells from apices of neural fold move away from the central part of the ns to form form groups lying dorsolateral to the spinal cord
what does the rostral part of the neural tube form in the cns
brain
what does the caudal portion of the neural tube form in the cns
spinal cord
what does the central cavity in the neural tube form in the cns
centre canal of the spinal cord
ventricles of the brain
what do the neural crests form
sensory ganglia of spinal and cranial nerves and the autonomic ganglia
what are the derivatives of the neural crest
dorsal root ganglia, melanocytes, odontoblasts, parafollicular cells, thyroid, adrenal medulla, autonomic . ganglia, cartilages of trachea, schwann cells
what occurs in neural tube defects (NTDs)
failure of closure of neural pores
what is spina bifida (1) & anencephaly (2)
the most common neural tube defects where the fetal spinal column doesnt close completely (1) and most of the brain and skull do not develop (2)
how can spina bifida and anencephaly be reduced
supplement of folic acid before conception and during the first trimester of pregnancy
what does maternal alpha screen for
fetoprotein levels in the blood which are increased in neural tube defects
how does folic acid help reduce NTDs
helps with the division of nerve cells and the formation and closure of neural tubes
what does rostral mean
towards the anterior part of brain
what does caudal mean
towards the posterior part of the brain
what are the primary brain vesicles
prosencephalon (forebrain)
mesencephalon (midbrain)
rhombencephalon (hindbrain)
what are the secondary vesicles of the forebrain
diencephalon - thalamus
telencephalon- cerebral hemisphere
what are the secondary vesicles of the midbrain
mesencephalon (midbrain)
what are the secondary vesicles of the hindbrain
metencephalon (pons, cerebellum)
myelencephalon (medulla oblongata)
what is a haematopoetic stem cell
cells which originate from the bone marrow and form WBC and RBC- microglial cells
what do embryonic cns stem cells differentiate into
glial progenitor (astrocytes & oligodendrocytes) and neuronal progenitor (nerve cells)
what is the location and function of the premotor cortex
immediately anterior to the primary motor cortex in frontal lobe
programmes what we need to do to control movement
what is the supplementary motor cortex
region of the premotor cortex on the medial surface of the hemisphere
what is the primary somatosensory cortex
region in the parietal lobe
thalimocortical (third order) neurones terminate here. carry general sensation to a conscious level
what happens of there is damage to the primary somatosensory cortex
damages the ability to feel pain and temp
function of parietal association cortex
interpretation of general sensory information and conscious awareness of the contralateral half of the body
location and function of primary auditory cortex
temporal lobe
conscious perception of sound
location and function of the auditory association cortex - Wernike’s area
temporal lobe
processing and interpretation of auditory info- speech comprehension
location and fucntion of Brocas area
frontal lobe- in the inferior frontal gyrus
motor speech area
location of hippocampus
lies in floor of inferior horn of lateral ventricle in temporal lobe
function of hippocampus
function in memory and emotional aspect of behaviour
what is the amygdala
part of limbic system in temporal lobe
conscious appreciation of sense of smell
location and function of primary visual cortex
occipital lobe at location of calcarine sulcus
visual perception
location and function of visual association cortex
rest of occipital lobe
interpretation of visual images
what would a lesion of the primary visual cortex cause
blindness in the corresponding part of the visual field
what would damage to visual association cortexes cause
deficits in visual interpretation and recognition
what are the two main blood circulations to the brain
carotid
vertebral
what do the vertebral arteries supply
upper spinal cord, brainstem, cerebellum and post part of the brain
what do the int carotid arteries supply
brain
what is the basilar artery formed by
2 vertebral arteries
what are the branches of the vertebral artery
posterior inferior cerebellar artery
ant & post spinal artery
meningeal branches
medullary branches
what are the branches of the basilar artery
anterior inferior cerebellar artery
pontine arteries
superior cerebellar arteries
posterior cerebral arteries (principle terminal br)
what is the pathway of the basilar artery
ascends along the ventral aspect of the pons
ends at ponto-midbrain junction
of which larger artery is the vertebral artery a branch
subclavian
which fo. does the vertebral pass through in the spinal cord
fo. transversarium
which fo. does the vertebral artery enter the cranial cavity
fo. magnum
what do the posterior cerebral arteries supply
visual cortex of the occipital lobe & inferomedial aspect of the the temporal lobe (media l lateral and post parts of cerebrum)
what do middle cerebral arteries supply
whole lateral surface of frontal, partietal and temporal lobes
what do anterior cerebral arteries supply
frontal and parietal lobes
what level does the common carotid bifurcate
C4
through what fo does the carotid artery enter the brain
carotid canal
once in the cranial cavity which sinus does the ICA pass through
cavernous sinus
what branches does the ICA give rise to
opthalmic
anterior chordial
posterior communicating
what are the two terminal br of ICA
anterior cerebral
middle cerebral
what does the meningeal br of the vertebral artery supply
falx cerebelli, a sheet of dura matter
what do ant & post spinal arteries supply
spinal cord spanning length
what does the posterior inferior cerebellar artery supply
cerebellum
what is the circle of willis
where terminal br of vertebral and ICA anastomose to form circular blood vessels
what are the main paired constituents of the circle of willis
ant cerebral arteries
int carotid arteries
post cerebral arteries
ant & post communicating arteries
what are the 3 main arteries supplying the cortex
posterior, middle and anterior cerebral
what are ventricles
‘cavities’ in the brain formed by neural tubes
what is contained in ventricles
cerebrospinal fluid
what is cerebrospinal fluid produced by
choroid plexus (70%) ependymal cells (30%)
what is the function of CSF
removes waste metabolites
allows the brain to ‘float’
protective
provides stable ionic enviro
how many lateral ventricles are there
2
one in each hemisphere
what is the 3rd ventricle
midline, slit-like cavity with its lateral walls consisting if the thalamus and hypothalamus
how are the 3rd and 4th ventricle connected
by the cerebral aqueduct which underlies the cerebellum
what is the pathway for CSF flow
choroid plexus secretes csf in lateral ventricle
increase in pressure so csf flow into 3rd ventricle via interventricular fo.
flows from 3rd into 4th ventricle via cerebral aqueduct
csf leaves ventricular system via 3 apertures of 4th ventricle & enters subarachnoid space
csf absorbed into the venous system through arachnoid villi
what is the CSF composed of
small amounts of protein, glucose, ions (ca, k, na, cl, mg)
what does the ventricular system consist of
lateral ventricle
3rd ventricle
cerebral aqueduct and fourth ventricle
how does the lateral ventricle communicate with the third ventricle
via the interventricular foramen within the 3rd ventricle
what does each ventricle contain that secretes CSF
choroid plexus
what would be the implications of an occlusion in the anterior cerebral arteries
contralateral hemiparesis affecting leg more than arm
grasp reflex and motor dysphasia
cognitive changes
personality changes
what would be the implications of an occlusion in the middle cerebral arteries
Total Anterior Circulation Stroke (TACS)
contralateral hemiparesis and sensory loss of a cortical type
dysphasia if lesion in dominant hemisphere
what would be the implications of an occlusion in the posterior cerebral arteries
Visual hallucinations, visual agnosias
The vital memory structures are supplied from the posterior cerebral artery
what would be the implications of an occlusion in the basilar artery
locked in syndrome
pons affected
what is derived from the telencephalon
cerebral hemisphere
lateral venetricles
what is derived from the diencephalon
thalamus
third ventricle
what is derived from the mesencephalon
midbrain
aqueduct
what is derived from the metencephalon
pons and cerebellum
upper part of the 4th ventricle
what is derived from the myelencephalon
medulla
lower part of fourth ventricle
