Cerebral hemispheres Flashcards
what is a sulcus?
a dip
what is a gyrus?
an elevation
what is a fissure?
a larger dip
what is the surface of the brain made of? and the inside?
- surface = grey matter
- inside = white matter
what is the basal ganglia?
are a collection of cell bodies buried in the white matter
what does the corpus callosum contain, in terms of fibres?
commissural fibres (connecting the 2 hemsipheres)
where does the central sulcus lie?
it lies between the precentral & postcentral gyrus
what does the transverse fissure split?
splits the cerebrum from cerebellum
label this
A- central sulcus
B-frontal lobe
C-sylvian/lateral fissure
D-temporal lobe
E-transverse fissure
F- occipital lobe
G- parietal lobe
what does the median longitudinal fissure separate?
the 2 hemispheres of the brain, longitidinally
what are heschl’s convolutions?
transverse gyri of temporal lobe
what are the different functions of the different lobes?
- frontal lobe –> motor function, intellect
- parietal lobe –> somatosensory
- occipital lobe –> vision
- temporal lobe –> hearing and smell
the medial portion of the cerebral hemisphere, the limbic system, is important for what?
storage and retrieval of processed information
where are auditory association areas?
in temporal lobe on each side, but only in the dominant it is designed to allow you to understand language
what is the precentral gyrus also known as and what area is it, and in what lobe is it found?
primary motor cortex, area 4 in FRONTAL LOBE
what does the motor homonculus represent?
somatotopic representation of contralateral half of body
what other areas are contained within the frontal lobe?
- prefrontal cortex
- Broca’s area of motor speech
what is the function of Broca’s area and where is it found
- has a primary function in speech production
- found in both hemispheres
what is the function of the prefrontal cortex?
is involved in higher order functions ie judgement, intelligence, planning etc
what is the order of processes which result in speech?
prefrontal cortex –> broca’s area –> precentral gyrus
in what lobe is the postcentral gyrus found, what is it also known as and what areas is it?
- parietal lobe
- also known as primary sensory area
- areas 1,2,3
what other areas are there in the parietal lobe?
- superior parietal lobule
- inferior parietal lobule
what is the function of the superior parietal lobule?
interpretation of somatosensory information & conscious awareness of contralateral half of body
what is the function of inferior parietal lobule?
interface between somatosensory cortex & visual and auditory association areas
what happens when there is a lesion of the parietal lobe? (4) dominant and non dominant
- hemi-sensory neglect - this is defined as the inability of a person to process sensory stimuli from one half of the body
- right-left agnosia (inability to differentiate right from left)
if occurs in dominant lobe..
- acalculia (can’t count)
- agraphia (can’t write)
what is the main field in the temporal lobe and what number is it?
- primary auditory cortex
- areas 41 and 42
what area does the temporal lobe have on the dominant side and what is its’ function?
Wernicke’s area - essential for the recognition of the spoken word
what does the inferior surface of the temporal lobe recieve?
fibres from the olfactory tract - conscious appreciation of smell
what is the main field in the occipital lobe and what is its’ area?
primary visual cortex - area 17
where does the primary visual cortex lie?
on either side of the calcarine fissure
what is the rest of the occipital lobe, what is the area and what is it responsible for?
- visual association cortex
- areas 18,19
- repsonsible for interpretation of visual images
what is aphasia?
person has difficulty with speech due to damage to one or more speech areas of the brain
what is the main difference between broca’s aphasia and wernicke’s aphasia?
broca’s –> understands speech
wernicke’s–> can’t understand speech, doesn’t know of mistakes
what are the 3 different types of white matter tract fibres?
- commissural fibres
- projection fibres
- assosciation fibres
describe commisural fibres
they Connect correpsonding areas of 2 hemsipheres ie corpus callosum
describe projection fibres
they run between the cortex and various subcortical structures & spinal cord
ie basal ganglia, thalamus, brainstem etc
describe asociation fibres
they conect one part of the cerebral cortex with another
what is the internal capsule and what is it made up of?
- it is a narrow area between the caudate nucleus and thalamus medially and lentiform nucleus laterally
- made up of projection fibres passing to and from cerebral cortex
from what does internal capsule derive its blood supply?
middle cerebral artery
what is the function of the basal ganglia?
it starts, stops and regulates the intensity of voluntary movements
what is the basal ganglia composed of?
- putamen
- globus pallidus
- caudate nucleus
- substantia nigra - but not anatomically part of it
what makes up the lentiform nucleus?
- globus pallidus
- putamen
where, anatomically, does the caudate nucleus lie?
lies in the wall of the lateral ventricle
label this, from top right clockwise
- caudate nucleus
- putamen
- globus pallidus
- III ventricle
- thalamus
- lentiform nucleus
- lateral ventricle
where, anaotmically, does the thalamus lie?
next to the third ventricle
how does the basal ganglia system work?
- caudate nucleus AND putamen recieve input from motor/premotor cortex / thalamus
- they then transfer this signal to the globus pallidus and substantia nigra
- globus pallidus projects primarily to thalamus
- thalamus sends fibres to motor cortex
