Cerebral hemispheres Flashcards
what are the general features of the cerebral hemispheres
sulcus - dip
gyrus - elevation
fissure - larger dip
grey matter on surface
white matter inside
lateral ventricle in the cavity of each hemisphere
what is the name of the fissure that runs down the centre of the cerebrum from front to back
median longitudinal fissure
what connects the right and left cerebral hemispheres
the corpus callosum - contains commissural fibres
what is the name of the sulcus that runs across the top of the cerebrum left to right and what lies on either side
central sulcus
in front - precentral gyrus
behind - post central gyrus
what does the central sulcus separate
parietal lobe from the frontal lobe
what separates the parietal and occipital lobes
parieto-occipital sulcus
what does the cingulate sulcus separate
parietal and frontal lobes from the cingulate gyrus
what does the lateral sulcus (sylvan fissure) separate
parietal and frontal lobes above from temporal lobe below
what is the posterior part of the cerebrum for
sensory
parietal - somatosensory
occipital - vision
temporal - hearing and smell
what is the anterior part of the cerebrum for
motor
frontal - motor function and intellect
what are the medial portions of the brain for
limbic system - storage and retrieval of processed information
within the frontal lobe - what are three important areas
area 4 - precentral gyrus
area 44,45 - inferior frontal gyrus
prefrontal cortex
what happens in area 4 of the frontal lobe
precentral gyrus = PRIMARY MOTOR CORTEX
somototopic representation of contralateral half of the body
what happens in areas 44,45 of the frontal lobe
inferior frontal gyrus = BROCAS AREA
motor speech
what happens in the prefrontal cortex
cognitive functions of higher order intellect
judgement
prediction
planning
within the parietal lobe - what are 3 important areas
areas 1,2,3 - post central gyrus
superior parietal lobule
inferior parietal lobule
what happens in areas 1,2,3 of the parietal lobe
post-central gyrus = PRIMARY SENSORY CORTEX
recieves general sensations from contralateral half of body
what happens in the superior parietal lobule
interpretation of general sensory info and conscious awareness of contralateral half of body
what happens in the inferior parietal lobule
interface between somatosensory cortex and visual and auditory association areas
in dominant hemisphere = contributes to language functions
what can occur if there is a lesion in the parietal lobe
hemisensory neglect
right-left agnosia
acalculia
agraphia
what is hemisensory neglect
the inability of a person to process and perceive stimuli on one side of the body or environment, where that inability is not due to a lack of sensation
what is right-left agnosia
inability to differentiate right and left
what is acalculia
difficulty perfoming simple mathematical tasks - different from dyscalculia as it is neurologically acquired later in life e.g. from stroke
what is agraphia
loss of the ability to communicate through writing
within the temporal lobe - what are 3 important areas
areas 41,42 - superior temporal gyrus
auditory association areas
inferior surface
what happens in areas 41,42 of the temporal lobe
superior temporal gyrus = PRIMARY AUDITORY CORTEX
what happens in the auditory association areas of the temporal lobe
WERNICKES AREA - understanding spoke word
what happen in the inferior surface of the temporal lobe
conscious appreciation of smell
within the occipital lobe - what are 2 important areas
area 17 - either side of the calcarine sulcus
areas 18,19 - visual association cortex
what happens in area 17 of the occipital lobe
PRIMARY VISUAL CORTEX
what happens in areas 18,19 of the occipital lobe
interpretation of visual images
what does the limbic lobe include
cingulate gyrus, hippocampus, parahippocampal gyrus, amygdala
what is the role of the limbic lobe
memory and emotional aspects of behaviour
what are the two language areas of the brain
brocas - motor speech
wernickes - recognition of spoken word
damage in either area can cause aphasia
what occurs in brocas aphasia
damage to frontal lobe
can understand speech
misses small words out e.g. “walk dog” instead of “walk THE dog”
aware of difficulties in speech
weakness/paralysis of one side of the body
what occurs in wernickes aphasia
damage to temporal lobe
can’t understand speech
fluent speech with new meaningless words e.g. “you know what poodle and that I want to get and round him like you want before”
unaware of mistakes
no paralysis
what are the three types of white matter myelinated axon fibres and what do they do
commissural - connect hemispheres
association - connect one part of cortex with another
projection - connect cerebrum with subcortical centres e.g. spinal cord
what is the internal capsule
narrow area projection fibres passing to and from cerebral cortex
derives blood supply fro middle cerebral artery - frequently affected in stroke
what are basal ganglia
collection of neuronal cell bodies (grey matter) buried deep within the white matter of each hemisphere
what are the 3 main basal ganglia
caudate
putamen
globus pallidus
(subthalamic nucleii)
what is functionally part of the basal ganglia but not anatomically
substantia nigra - found in the midbrain
what is the major function of the basal ganglia
initiation and termination of movements
what are common pathologies o the basal ganglia
parkinsons, athetosis, chorea
what are the input regions of the basal ganglia
caudate
putamen
what are the output regions of the basal ganglia
globus pallidus
substantia nigra
globus plaids then projects to thalamus - sends fibres to primary motor cortex
SUMMARY: general structure of the cerebral hemispheres
outer grey matter
inner white matter
deep in white matter - basal ganglia (grey matter)
SUMMARY: what separates and connects the two lobes respectively
median longitudinal fissure
corpus callosum
SUMMARY: what are the 2 main sulcii
central
lateral
parieto-occipital
SUMMARY: what is the role of the frontal lobe
thinking, motor cortex, brokers speech area
SUMMARY: what is the role of the parietal lobe
sensory
SUMMARY: what is the role of the temporal lobe
auditory, wernickes areas (language), smell
SUMMARY: what are the three fibres in the white matter
association
commissural
projection
SUMMARY: what do the basal ganglia do
control movement by connecting to motor cortex (starting and stopping of movements)
