B2 - cerebral localisation Flashcards
the cerebral hemisphere is derived from the embryological ______?
telencephalon
function of gyri and sulci?
maximise SA of cerebral cortex
name 2 additional masses of grey matter deep within the cerebral hemisphere
thalamus + basal ganglia (caudate nucleus, putamen + globus pallidus)
what is the name of the broad sheet where the vast majority of the nerve fibres that pass between the cerebral cortex and the subcortical structures are condensed deep within the hemisphere?
internal capsule
what type of fibres are in the internal capsule?
projection fibres
between the internal capsule and cortical surface, fibres radiate in and out to produce a fan-like arrangement, called the _____?
corona radiata
what is the cerebrum divided into 2 cerebral hemispheres by?
longitudinal fissure
what are the cerebral hemispheres separated by?
falx cerebri
what is the corpus callosum?
an enormous sheet of commisural nerve fibres that unite the 2 cerebral hemispheres
what is the insula?
a region of cortex deep in the lateral sulcus
what does the calcarine sulcus indicate the location of?
primary visual cortex
where is the primary sensory cortex?
post central gyrus
where is the primary motor cortex?
precentral gyrus
label
what is the opercula?
the parts of the frontal, parietal and temporal lobes that overlie the insula
what is the lateral fissure?
a fissure separating the temporal lobe from the frotnal and parietal lobes above
brief functions of each lobe
what does the central sulcus do?
divides frontal from parietal lobe
what does lateral sulcus do?
divides temporal from frontal and parietal
in what lobe is the calcarine fissure?
occipital
where is the primary auditory cortex?
superior temporal gyrus of temporal lobe
where is Broca’s area (motor speech area)?
in inferior frontal gyrus (in frontal lobe above lateral fissure)
where is Wernicke’s area (auditory association area)?
near back of temporal lobe
damage to broca’s vs wernicke’s
broca’s — words dont come out
wernicke’s — words spoken perfectly but dont make sense
describe the 6 layers of the cerebral cortex
WHITE MATTER: beneath the cortical surface lies an extensive mass of nerve fibres all of which have their origin or termination (or sometimes both) within the cortex. the fibres are classified into 3 types depending upon their origin and destination — what are the 3 types?
- association — interconnect cortical sites lying within one hemisphere
- commisural — run from one hemisphere to another, connecting functionally related structures
- projection — pass between the vertebral cortex and subcortical structures such as the thalamus, striatum, brainstem and spinal cord
what is the major interhemispheric commissure?
corpus callosum
what are the parts of the corpus callosum from rostral to caudal?
rostrum, genu, body, splenium
what does the splenium do?
- part of the corpus callosum
- interconnects the occipital cortices
- therefore involved in visual functions
what is the anterior commissure?
connects structures of the olfactory pathway, amygdalas and temporal lobes
what is the posterior commissure?
connects the language processing areas of both cerebral hemispheres
what is the hippocampal commissure?
connects the hippocampi of both cerebral hemispheres
what is the name of the sheet of projection fibres that carries nearly all of the axons to and from the cerebral cortex?
corona radiata
what does the corona radiata continue ventrally as?
internal capsule
what is the name of short association fibres that link near-by areas by arching beneath the cerebral sulci?
u-fibres
what does the large superior longitudinal fasiculus interconnect? type of fibres?
- association fibres
- interconnects the frontal and occipital lobes
what is a subsidiary of the superior longitudinal fasciculus? function?
= arcuate fasciculus
- links gyri in the frontal and temporal lobes — important for language function
what does the uncinate fasciculus do?
connects the anterior and inferior parts of the frontal lobe with the temporal gyri — important structures in the regulation of behaviour
what is the cingulum?
- association fibres
- lies within the cingulate gyrus and courses parallel with the corpus callosum
- connects with frontal and parietal lobes with the parahippocampal and adjacent temporal gyri
label
from another view
what is the association cortex? what is it critical for?
the cortex where the 3 cerebral lobes meet — critical for the multimodal and spatial recognition of the environment
what is the anterior part (frontal lobe) of the cerebral cortex for?
organisation of movement (primary motor area; pre motor and supplementary motor areas) and the strategic guidance of complex motor behaviour over time (prefrontal area)
why is the left hemisphere said to be dominant for language?
in the majority of individuals, areas of association cortex in frontal, parietal and temporal lobes of the left hemisphere are responsible for the comprehension and expression of language
what is Brodmann’s areas 41 and 42?
parts of the primary auditory cortex
damage to primary visual cortex vs visual association area?
- primary visual cortex = blindness
- visual association area = deficits in visual interpretation and recognition
what does each hemisphere excel in: left hemisphere vs right hemisphere? when does this become established? effects of this?
> in the great majority of people, the left hemisphere is dominant for language and mathematical ability
the right hemisphere excels at spatial perception and musical proficiency
> cerebral dominance becomes established during the first few years after birth
during this formative period, both hemispheres exhibit linguistic ability and if one hemisphere sustains damage it may be compensated for by the plasticity of the developing brain and the child learns to speak normally
later in life this flexibility becomes greatly diminished
where are the language areas of the brain organised?
around the lateral fissure of the cerebral hemisphere
describe Broca’s area
- in frontal lobe
- occupies the posterior part of the inferior frontal gyrus, adjacent to the motor cortical area for the head and neck
- this region is concerned with expressive aspects of language (articulation)
describe Wernicke’s area
- in temporal lobe
- responsible for comprehension of the spoken word
what does the frontal lobe lie immediately in front of?
the central sulcus
what lies in front of the precentral gyrus?
precentral gyrus = primary motor region
- anterior to this lie the premotor and supplementary motor cortices
- and in the left hemisphere, broca’s area
what is the prefrontal cortex concerned with?
complex cognitive functions
what lies posterior to the central sulcus?
parietal lobe
describe the postcentral gyrus
- primary somatosensory area
- receives afferents from the ventral poster nucleus of the thalamus (site of termination of the spinothalamic tracts, trigeminothlamic tract and medial lemniscus)
what lies behind the postcentral gyrus?
sensory association area — responsible for interpretation if general sensory info
what lies beneath the lateral fissure?
temporal lobe
what marks the location of the primary auditory cortex?
the transverse temporal gyri (Herschl’s convolutions) on the superior surface on the superior temporal lobe
what does the primary auditory cortex receive?
input from the medial geniculate nucleus of the thalamus
what lies adjacent to the primary auditory cortex? what is it responsible for?
auditory association cortex — responsible for interpretation if auditory information and which in the left hemisphere constitutes Wernicke’s area
what indicates the location of the primary visual cortex?
the calcarine sulcus on the medial surface of the occipital lobe
what does the primary visual cortex receive?
afferents from the lateral geniculate nucleus of the thalamus
what makes up the rest of the occipital lobe (after the primary visual cortex)?
the visual association cortex — responsible for the interpretation of visual information
