Nervous system Flashcards
What is the cerebral cortex?
A region of grey matter that forms the outer layer of the cerebrum (brain)
How thick is the cerebral cortex?
2-4mm thick
What cells dominate the cerebral cortex?
Neurons. (billions in layers)
What happens when brain size increases rapidly? (grey and white matter)
Grey matter enlargers fast compared to white matter (underneath)
What are cerbral cortex folds called? (the peaks)
Gyrus (gyri)
What are the cerebal cortex small valleys called?
Sulcus (sulci)
The deepest grooves/valleys between folds are called?
Fissures
What does the longitudinal fissure (falx cerebri) do?
Separates the cerebral cortex into 2 hemispheres (LHS and RHS)
What are the four cerbral cortex lobes?
frontal, occipital, temporal and porietal
The frontal lobe controls:
Cognitive function, intelligence, mood, behaviour, personality
The temporal lobe controls:
Memory, intelligence, aggression, mood
The occipital lobe controls:
primary visual cortex
Parietal lobe controls:
Spatial skills and 3D recognition
The temporal and frontal lobe both play a role in controlling what?
Intelligence and mood
The frontal lobe and parietal lobe are primarily separated by what fissure?
Lateral fissure
The temporal lobe and parietal lobe are partially separated by what fissure?
Lateral fissure
What is the corpus callosum?
Broad band of white matter containing axons between hemispheres which connects the 2 cerebral hemispheres
What is the cerebrum described as?
A sea of intelligence (provides us with the ability to read, write, and speak; to make calculations and compose music; to remember the past and plan for the future; and to create.)
The precentral (major) gyrus is before or after the central sulcus?
Before
The postcentral (major) gyrus is located before or after the central sulcus?
After
What does the precentral gyrus contain?
Primary motor area
What does the postcentral gyrus contain?
Primary somatosensory area
What is insula?
The fifth part of the cerebrum. It cannot be seen at the surface of the brain.
Cerebral white matter contains what?
Myelinated axons
How many types of tracts does cerebral white matter have and what are they?
3 - association, commissural and projection tracts
Association tracts contain what?
Axons that conduct nerve impulses between gyri in the same hemisphere.
Commissural tracts contain what?
Axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere. Three important groups of commissural tracts are the corpus callosum (the largest fibre bundle in the brain, containing about 300 million fibres), anterior commissure, and posterior commissure.
Projection tracts contain what?
Axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere. Three important groups of commissural tracts are the corpus callosum (the largest fibre bundle in the brain, containing about 300 million fibres), anterior commissure, and posterior commissure.
What are the basal nuclei?
Three nuclei deep within each hemisphere (grey matter masses)
What is the role of basal nuclei?
Basal nuclei help initiate and terminate movements, suppress unwanted movements, and regulate muscle tone
What are the basal nuclei next (lateral) to?
Thalamus
What are the three basal nuclei?
Caudate nucleus, Putamen, Globus Pallidus
What do sensory areas recieve?
Sensory information and are involved in perception, the conscious awareness of a sensation
Parts of the limbic system:
What do motor areas control? (e.g. primary motor area)
Sensory information and are involved in perception, the conscious awareness of a sensation
What do association areas control?
deal with more complex integrative functions such as memory, emotions, reasoning, will, judgement, personality traits, and intelligence
Brocas area (in frontal lobe) does what?
plans and articualtes speech
Wernickes areas does what?
Helps understand and process speech
Arcuate fasiculus is abundle of white matter that connects wernickes to brocas area so that…
speech can be interpreted and then articulated
Wernickes and brocas are connected by what?
Arcuate Fasciculus
What does the primary auditory cortex in the temporal lobe allow for?
allows you to recognise a particular sound as speech, music, or noise
How is the primary auditory cortex organised?
In a tonotopic way = tone in relation to time which can then be ordered logically and interpreted by the wernickes area
What does aphasia impact?
Broca’s speech area, Wernicke’s (posterior language) area, and other language areas are located in the left cerebral hemisphere of most people
What is aphasia?
Damage to language areas of the cerebral cortex
Non-fluent aphasia =
Damage to brocas speech area, which results in an inability to properly articulate or form words (e.g. know what you want to say but can’t say it)
Fluent aphasia =
damage to wernickes area resulting in faulty understanding erstaning of spoken or written words. (e.g. stringing words together with no meaning)
What does homunculus mean?
A representation of the human body in the brain - different areas of that part of the brain correspond to areas of the body (A body map)
Why do some parts of the body have a larger representation in the primary motor cortex than others?
Some areas of the body have larger representation because there needs to be finer control of the muscles innervated in that area
What is the function of the pyramidal tract?
Initiating, controlling and stopping voluntary movement
What type of movement in the pyramidal pathway important for?
Voluntary movement
upper motor neurons are also known as
pyramidal cells
Pyramidal tract: UMN descend from where (begin)
Primary motor cortex
Pyramidal tract pathway order:
Primary motor cortex - Internal capsule (bypassing thalamus, crus cerebri and pons) - Pontine nuclei (where deviation into smaller bundles occur - medulla - (85% neurons decussate into pyramidal decussation and lateral corticospinal tract) - other 15% of axons down vertical cortico spinal tract before decussating at the spinal segmental level of LMN - leaves through ventral root to innervate skeletal muscles
The pyramidal tract works closely with
The basal ganglia system
The basal ganglia system has what role?
initiates, smooths and refines movement
Where does the basal ganglia system loop from and to?
Looping from the premotor cortex through the basal ganglia circuitry back to the premotor cortex, the nerves of which stimulate the upper motor neurons of the pyramidal tract, located in the primary motor cortex.
Damage to lower motor neurons causes?
Flacid paralysis
Damage to upper motor neurons causes?
Spastic paralysis
Symptoms of flaccid paralysis?
no nervous control of muscle at all and decreased muscle activation and therefore less/decreased tone
Symptoms of spastic paralysis?
Jerky movements and increased muscle activation and therefore more/increased tone
Does the basal ganglia have direct input/output to spinal chord?
No
Roles of the basal ganglia in movement control:
conveying mood through thought, initiating movement, modifying movement to be smoother/more controlled/precise
Does the cerebellum have direct output (not input) to the spinal chord?
Yes
Roles of the cerebellum in movement control:
Maintains balance,
Coordinates, maps, terminates and works with unconscious movement e.g. swinging arms while walking,
Adjusts movements to account for discrepancy between planned and actual movements
Diseases involving the left side of the cerebellum results in what?
uncoordinated movements and the loss of balance on the left side of the body, and lesions of the basal ganglia on the left side of the brain result in unrefined movements on the right side of the body.
Left spastic paralysis is due to damage to what cortex in what hemisphere??
Primary motor cortex, right hemisphere
Left spastic paralysis in the primary motor cortext affects what gyrus in what lobe?
precentral gyrus, frontal lobe
In spastic paralysis is the UMN or LMN impacted?
UMN. (transmitting information from the cortical area for the left side of the face and upper limb being damaged. )
A loss of sensation in the left hand would have been due to damage in … cortex of the … hemisphere
somatosensory cortex, right hemisphere
A loss of sensation in the left hand would have been due to damage in the somatosensory cortex occurs in what gyrus and lobe?
post sentral gyrus and parietal lobe
A loss of sensation in the left hand corresponds to hand dmaage in what?
the homunculus
A loss of hearing is due to damage in what cortex?
Primary auditory cortex (right hemisphere if damage occurs in left ear)
A loss of hearing in the left ear is a result of damage to the primary auditory cortex would occur in what gyrus?
Superior temporal gyrus
Problems with non-verbal communication would be due to damage in the dominant or non-dominant at hemisphere?
Non- dominant (usually right hemisphere)
parietal association cortex is most likely affected
What are the characteristic motor symptoms of Parkinson’s disease?
hypokinesia (inc bod movement), tremor at rest, rigidity
