Forebrain Flashcards
What is the corpus callosum?
largest white matter tract
- communication between the two hemispheres
Where is the cingulate gyrus found?
wrapped around the corpus callosum
What does the CSF drain through from the lateral ventricles to the 3rd ventricles?
intraventricular foramen (foramne of munroe)
How does CSF get from 3rd ventricle to 4th ventricle?
cerebral aqueduct
What are the two pathways that CSF drains from the 4th ventricle?
Laterally in formina of luschka or medially through formina of Magendie
What cells are part of chrorid plexus and involved in CSF production?
Ependymal cells
What happens when theres mutations in ependymal cells?
hydocephalus (build up of fluid in brain, increases pressure)
What is the internal capsule?
White matter that separates thalamus, putamen, globus pallidus and caudate (two limbs: anterior and posterior ‘V shaped’
Where is external capsule located?
claustrum (lining) of basal ganglia
What is the insula?
cortex in the lateral fissure
What makes up the striatum?
head of caudate, anterior loimb of internal capsule and putamen
What makes up the lentiform nucleus?
putamne and globus pallidus
what are the part sof the corpus callosum?
genu (anterior)
splenium (posterior)
Body
what is the massa intermedia?
present if two thalami are close enought together (not everyone has it)
Function of the thalamus?
- sensory relay station
- cerebellar and BG relays to motor frontal lobe
- connected to associative and limbic area
What happens if theres damage to thalamus?
loss of sensation, pain or movement disorders
where does the anterior nucleus of the thalamus project to?
cingulate gyrus
wha is the lateral geniculate body involved with?
vision
what is the medial geniculate body involved with?
auditory information
what makes up the basal ganglia?
Caudate nucleus (head and tail)
Putamen
Globus pallidus (internal and external)
Function of basal ganglia?
intermediate level initiation and coordination of movement
What is activity of the basal ganglia facillitated by?
DA from the substantia nigra
what is the direct pathway?
Facillitates voluntary movement
- motor cortex to striatum to GPi and substantia nigra to thalamus
what is the indirect pathway?
- inhibits movement
- motor cortex to striatum to globus pallidus external, to subthalamic nucleu to GPi to thalamus
How is the BG involved in PD?
DA neurons lost in the substantia nigra, impairs the ability to initiate movement
Affects of Huntingtons disease on striatum?
atrophy of head of caudate occurs
- causes involuntary movement
What is the nucleus basalis of Meynert?
- underneath the anterior commisure
- main source of ACh to whole brain
Clinical significance of nucleus basalis of Meynert?
In AD many neurons in nucleus basalis are lost
- decrease ACh
Clinical significance of nucleus basalis of Meynert?
In AD many neurons in nucleus basalis are lost
- decrease ACh
Function of hypothalamus?
homeostasis
- main output is pituitary gland
What does the entorhinal cortex do?
Funnels information into hippocampus
what are fimbriae?
output from hippocampus that forms the fornix
Limbic system circuit?
Fornix attaches round to mammillary bodies -> project to thalamus (via mammillothalamic tract)->cingulate gyrus->cingulum-> entorhinal cortex
What part of the hippocampus is particulary susceptible to hypoxic ischaemic processes?
CA1
What is the only sensory system that does not get wired via the thalamus?
olfactory system
what is the dentate gyrus?
afferent portion of hippocampus that receives major projection from enterohinal cortex (perforant path)
what are lesions of hippocampus associated with?
anterograde amnesia (forming new memories)
what cells make up the cortex?
inhibiotry interneuorns, pyramidal cells, glia etc.
What are the characteristic architectural features of the cortex?
columar (neurones align vertically)
lamina (different cells in different layers)
whats the names of the large pyramidal cells in layers 2,3,5 and 6?
Betz cells
whats the rule on the size of the neurons?
size of cell body relates to the length of the axon it gives rise to
where does layer 5 project to?
brainstem and spinal cord (larger neurons, have to project further)
where does layer 6 project to?
projects to thalamus
what is the operculum?
lips of lateral fissure
whats the function of the insula?
emotion, homeostasis, perception, motor control, slef awareness, cognitive functioning and interperosnal experience
where is brocas area and what is its function?
frontal lobe
- language production
what is wernickes area and where is it found?
language interpretation and temporal lobes
function of oligodendoryctes?
- speeds up AP
- trophic support (energy in form of lactate)
what are association fibres?
communicate withiin a cerebral hemisphere
what are commissural fibres?
communicate between hemispheres as well as within hemispheres
what are projection fibres?
go up and down to deeper structures eg. brainstem and spinal cord
