L9 - localisation Flashcards
how thick is the cerebral cortex
2-4mm
role of gyri and sulci
increase surface area
lamina
layers of cortex
central sulcus
divides frontal and parietal lobes
lateral sulcus
divides the frontal and temporal lobes
parieto-occipital sulcus
separates parietal and occipital lobes
cingulate sulcus
runs parallel with corpus callocum
shape of cingulate sulcus
C shaped
where can the cingulate sulcus be seen
medial view
collateral sulcus
indicates position of parahippocampal gyrus
location of collateral sulcus
hooks backwards on itself to form a medially projected bump - uncus
which lobe is the collateral sulcus part of
temporal
role of limbic lobe
emotion and memory
uncas
bottom part of limbic lobe
uncal herniation
if the uncus herniates below the cerebella, resulting in the uncus pressing on the midbrain
potential sites of uncal herniation
beneath the free edges of the meninges
consequence of uncal herniation
compression on the brainstem
tonsils herniation
when tonsils in the cerebellum herniate and compress on the medulla oblongata
brodmann’s area
cortical map divided into 46 areas based on cellular organisation of the cerebral cortex
primary projection areas
perceive sensory or motor information
primary sensory areas
where specific sensory pathways terminate / how we perceive sensation
primary motor areas
specific motor pathways originate here
a lesion in Broca’s area can affect which artery?
middle cerebral artery
what do cerebral hemispheres include?
Include a dense core of white matter with an overlying thin layer of grey matter (cortex)
how many layers are there in the laminar arrangement of the cerebral cortex?
6
herniation of the brain below the tentorium cerebelli
uncal herniation
The parahippocampal gyrus hooks back on itself to form which structure?
the uncus
Which two gyri together form the limbic lobe?
Cingulate gyrus and parahippocampus gyrus
secondary projection sensory areas
- Receive input from primary sensory area
- Involved in interpretation / understanding
secondary motor areas
- Sends output to primary motor area
- Organises patterns of movement
location of primary motor cortex
pre-central gyrus
what does the primary motor cortex control?
voluntary contraction of specific muscles
it is somatotopically organised
what type of fibres are located in the PMC
descending motor fibres
location of association motor areas
anterior to PMC
BA 6 supplementary motor (sm) and pre-motor (pm) performs what movements?
- learned complex motor activities
- storage of those activities
e. g., tying shoe laces
BA 8 - frontal eye field location
frontal lobe
BA 8 - frontal eye field performs what movements?
controls voluntary movements of the eyes
BA 44, 45 (Broca’s area) controls what movements?
Regulates pattern of breathing and vocalization needed for normal speech
- How you articulate your language
location of Broca’s area
inferior frontal gyrus (typically localised to dominant hemisphere - usually left)
what would happen in an injury to the precentral gyrus
impaired movement or paralysis
what would happen in an injury to the motor associated areas
we would still be able move yet we would lose the ability to perform highly skilled movements
primary somatosensory cortex
post-central gyrus
The primary sensory cortex receives sensory pathways for which 5 senses?
- touch
- temperature
- vibration
- pain
- proprioception
Which 2 parts of the thalamus process sensory information, before relaying to the primary somatosensory cortex?
VPL (ventral posterior lateral) & VPM (ventral posterior medial) nuclei
route of information to PSC
- ascending sensory fibres towards post-central gyrus
- information is stopped in specific areas of the thalamus before relayed to the PSC
thalamus nuclei
used to discriminate where the information is coming from
Where does the lateral VPL receive input from?
From the leg and projects to the midline
Where does the medial VPL receive input from?
From arm and projects to lateral region
In somatotropin organisation, from lateral to medial, what is the order of the arms, legs, trunk and face?
Face
Arms
Trunk
Legs
FATL
Where does the VPM receive input from?
From the face and projects to the lateral region
location of association somatosensory areas - BA5,7
superior parietal lobe
What is the role of BA5, 7 - association somatosensory areas?
- interpretation, understanding and recognition
- spatial analysis
- identifies type of touch
injury to association association somatosensory areas (BA5, 7)
tactile agnosia
- cannot recognise the object they are touching
- however can still feel it
Where is the primary auditory cortex located (BA41, 41)?
Superior temporal gyrus (Heschl’s gyrus)
What is the role of the primary auditory cortex (BA41, 42)?
- conscious perception of sound
(however does not know the meaning of the sound as it is a primary not secondary cortex) - it is tonotopically organised
where does the primary auditory cortex receive signals from
- vestibulocochlear nerve and the nerve sends projections to the thalamus
- which knows where the information is coming from and where it needs to go
- sends to superior temporal gyrus
tonotopically organised
- Specrum of auditble frequencies is mapped onto the primary auditory cortex
- Lower frequencies are projected more medially
- Higher frequencies are projected more posteriorly
where are higher frequency sounds organised
more posteriorly
Which part of the thalamus relays sound information to the primary auditory cortex?
Medial geniculate nucleus
role of association auditory cortex BA22
gives meaning / significance to sound
location of BA22 association auditory cortex
surrounds primary auditory area
wernicke’s area
Interpretation of written or spoken word
primary visual cortex BA17 location
Located in the area around calcarine sulcus and occipital lobe
The primary visual cortex receives information from where?
The retina
role of association visual area BA18,19
- involved in interpretation of visual info
- recognises faces, objects
What is the consequence of a lesion to the association visual areas?
Prosopagnosia
- the inability to recognise faces
location / distribution the taste cortex?
Taste cortex extends from the inferior margin of the post central gyrus into the insula
what is the general association cortex involved in?
- involved in more complex aspects of behavioural and intellectual functioning
What are the roles of the prefrontal cortex?
- regulates moods and feelings
- involved in higher order cognitive functions
- involved in conceptualisation, planning and judgement
What are the roles of the parieto-temporal cortex?
- integrates information from different modalities
- involved in memory
- vision, hearing,touch and gives it all morning
aphasia
loss of ability to use language for speech
‘dys’
difficulty
language centres within the dominant hemispheres
broca’s and wernicke’s
location of broca’s area
inferior margin of the frontal lobe
What is the difference between dysphasia and aphasia?
dysphasia = difficulty with speech aphasia = loss of ability to speak properly
damage to broca’s area
- motor/non-fluent aphasia
- inability to correctly articulate speech despite understanding it perfectrly
damage to wernicke’s area
- sensory / fluent aphasia
- inability to understand language
- when speaking, words come out fluently yet do not make sense
arcuate fasciculus
association fibres which connect areas within hemispheres
- important in connecting broca’s and wernicke’s area
conduction aphasia
- impaired repetition
- can understand information however pathway is damaged so cannot repeat as cannot articulate speech
function of dominant hemisphere
- Linguistic function
- Numerical skills
non-dominant hemisphere
- Spatial awareness
apraxia
Damage to secondary motor areas leads to inability to carry out purposive movements, although there is no paralysis
