List the important sulci?
Where is the lateral sulcus?
On the lateral surface seperating the temporal lobe from the frontal/parietal
Where is the central sulcus?
On the lateral/superior surface and a little bit on the medial
It separates the parietal and frontal lobes
Where is the parieto-occipital sulcus?
On the medial surface separating the parietal and occipital lobes
Where is the cingulate sulcus?
On the medial surface separating the temporal lobe from the frontal/parietal lobes.
What are the important gyri to remember?
- Pre- and Post- Central gyri (i.e. in front and behind the central sulcus)
- Sup/middle/inf Frontal Gyri
- Sup/middle/inf temporal gyri
- Sup/Inf Parietal Lobules
How are the two cerebral hemispheres connected?
By the Corpus Callosum, which is bundle of commissural fibres (Type of white matter)
What are the types of white matter tracts?
Commissural - Connect two hemispheres
Association - From one part of the hemisphere to another (long or short)
Projection - Between Cerebral Cortex and subcortical centres i.e. sensory fibres coming in or motor fibres going out
What do the projection fibres form within the cerebrum?
The internal capsule
A small area of white matter.
Seen on a transverse section of the cerebrum lateral to the thalamus/caudate nucleus and medial to the lentiform nucleus
Why is the blood supply to the internal capsule important?
The middle cerebral artery, because if its affected by embolism it will affect most of the fibres entering or leaving the brain, whereas embolism to specific part of the cerebrum would only cause a localised stroke
Explain the dominant hemisphere?
One of your cerebral hemispheres is dominant to the other. This one contains more complex lobes such as Wernicke’s area in the dominant temporal lobe
Explain the difference between primary sensory areas and adjacent association areas?
A primary sensory area is the region that detects basic sensory stimulation.
The Association areas are around the primary sensory area and are essential for more complex mental function such as Wernicke’s area allows processing of sound as language
What is each lobe responsible for?
Frontal - Motor function and intellect
Parietal - Somatosensory
Occipital - Vision
Temporal - Hearing & Smell
What are the main functional areas of the frontal lobe?
- Area 4, the Precentral Gyrus or Primary Motor Cortex
- Area 6, The Pre-motor cortex and Supplementary Motor Area
- Area 44/45, the Inf. Frontal Gyrus or Broca’s Area of Motor Speech
- Prefrontal Cortex
Whats the function of the Primary Motor Cortex?
Area 4 i.e. Precentral Gyrus
Involved in most physical movement, it is where signals regarding movement are turned into activation of the motor neurons
Contains the Motor Somatotopic representation of the contralateral half of the body
What is the Inferior Frontal Gyrus responsible for?
Area 44/45 i.e. Broca’s Area of Motor Speech
Determines the physical production of speech
What is the prefrontal cortex responsible for?
Higher order intellect:
What are the main functional areas of the parietal lobe?
- Areas 1-3, Post-Central Gyrus or Primary Sensory Area
- Areas 5 & 7, Posterior Parietal cortex
- Superior Parietal Lobule
- Inferior Parietal Lobule
What is the function of the primary sensory area?
Areas 1-3 or Post Central Gyrus
It recieves general sensory info from the contralateral half of the body and produces the Sensory Somatotopic representation of the body
What does the superior parietal lobule do?
Responsible for interpreting general sensory info and your conscious awareness of the body
What does the inferior parietal lobule do?
It interfaces between the somatosensory cortex, visual and auditory areas.
In the dominant lobe its an associated area that contributes to language
What happens if you have a lesion of the parietal lobe?
Since the parietal lobe is responsible for handling sensory info and our conscious awareness of the contralateral side of our body:
Hemisensory neglect i,e, the paitent is unaware of one side of his body
It can also cause Acalculia & Agraphia
Define Acalculia and Agraphia
Acalculia - Difficulty performing basic mathematical tasks
Agraphia - Unable to write/read
What are the functional areas of the Temporal Lobe?
- Areas 41-42 i.e. the superior Temporal Gyrus or Primary Auditory Cortex
- Wernicke’s area (posterior to 41/42)
- Inferior Surface
Whats the function of Wernicke’s Area?
Its an auditory association area in the dominant hemisphere which is crucial for understanding sound as spoken language
Whats the function of the inferior surface of the temporal lobe?
Olfactory Fibres enter here so its responsible for smell
What is the limbic Lobe?
A functional rather than anatomical lobe
Its on the medial surface of the cerebrum and includes:
- Cingulate gyrus
- Parahippocampal Gyrus
- Amygdala (subcortical grey matter near the temporal pole)
It handles Emotion and memory
What are the important areas for language?
- Broca’s Area of Motor Speech (The inferior Frontal Gyrus)
- Wernicke’s Area (Posterior to the Superior Temporal Gyrus)
What happens if theres damage to the Inferior Frontal Gyrus?
- Broca’s Aphasia
The person cant form speech properly
Therefore they can understand speech and talk but miss alot of words
They’re aware of the problem and get frustrated.
Because of the relation of the inferior frontal gyrus to the pre-central gyrus (Primary Motor Cortex) it often comes with one-sided weakness/paralysis
What happens if theres damage to Wernicke’s Area?
The person speaks easily but uses meaningless words. They also dont understand what you say.
However they are unaware that they’re misunderstanding and don’t make sense.
What area is responsible for forming the motor somatotopic representation of the body?
The precentral Gyrus
I.e. The Primary Motor Cortex or Area 4
What area is responsible for the physical formation of speech?
The Inferior Frontal Gyrus
I.e. Area 44/45 or Broca’s Area of Motor Speech
What area of the brain is responsible for intellect?
The Prefrontal Cortex
What part of the brain handles general sensory info?
The Post-central gyrus
i.e. Areas 1-3, the Primary Sensory Area
Also the Superior Parietal Lobule interprets general sensory info and conscious awareness of the body
What area interfaces the somatosensory, visual and auditory associated areas?
Inferior Parietal Lobule
What section of the brain contains the primary auditory cortex?
The Superior Temporal Gyrus
This is areas 41-42`
What section of the brain handles understanding of language?
Wernicke’s area posterior to the superior temporal gyrus
What section of the brain contains the primary visual cortex?
Its on the medial surface of the occipital lobe either side of the calcarine sulcus
Which areas of the brain act as visual association areas?
They interpret visual images
What part of the brain handles emotion and memory?
The limbic lobe, includes:
- Cingulate Gyrus
- Parahippocampal Gyrus
Where is the hippocampus?
Under the cerebral cortex and specifically within the medial temporal lobe
Where is the amygdala?
A group of nuclei under the cerebral cortex, within the medial temporal lobe. Its at the tip of the hippocampus
Where is the cingulate gyrus found?
On the medial surface of the cerebrum just above the corpus callosum.
It’s the medial surafce of the temporal lobe, separated from the lobes above by the cingulate sulcus
What are basal ganglia?
Collections of grey matter deep inside the white matter
What do basal ganglia do?
They regulate initiation & termination of movements, feeding into the pyramidal system (hence they’re called the extrapyramidal system)
What pathologies affect the basal ganglia?
List the basal ganglia?
- Caudate Nucleus
- Lentiform Nucleus
- Substantia Nigra
Where is the caudate nucleus?
It follows the path of the lateral ventricle, lateral to it.
Where is the lentiform nucleus?
Lateral to the internal capsule
Made up of the Globus Pallidus (Medially) & the Putamen (Laterally)
Its lateral to and within the curve of the caudate nucleus
See the Cerebrum lecture notes for diagrams of the basal ganglia etc.
Where is the substantia nigra?
A basal ganglia actually found within the midbrain
Its 2 black strips within the midbrain
Which basal ganglia act as input regions from the cortex and which as output regions to the thalamus?
- Globus Pallidus
- Substantia Nigra
What is area 6 for?
(Pre-motor Cortex & Supplementary Motor Area)
Here movements are planned, it lights up 1s before we move.
This also lights up when we watch someone else move (so its where we comprehend movement of others) and when simply thinking about but not acting on a movement.
Whats the importance of the Posterior Parietal Cortex?
Posterior to the Primary Somatosensory cortex
It handles spatial reasoning and is involved in planned movements.
If its damaged you can end up with hemispatial neglect