Cerebral Hemispheres Flashcards
Where is the grey and white matter located on a brain?
Grey matter on the surface
White matter inside
What are basal ganglia?
Collection of neuronal cell bodies buried in the white matter
What are the names given to the dips and the elevations in the brain?
Dips - sulci or fissure if larger dips
Elevation - gyrus
Where are the 3rd and 4th ventricles located?
3rd - within the diencephalon
4th - pons and medulla infront and the cerebellum behind
What is the structure that connects the two hemishperes?
Corpus callosum - lots of commisural fibres
What is the name of the fissure that separates the cerebral hemisphere and the cerebellum?
Transverse fissure
Where is the parietal lobe in relation to the central sulcus?
Parietal lobe is behind the central sulcus
What does the lateral/sylvian fissure separate the temporal lobe from?
The frontal lobe and the parietal lobe
What are the structures labelled?
When is the parieto-occipital sulcus present?
Present on cross section
Look
Where is the insular cortex found in the brain?
It is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes)
What are the functions of the frontal lobe, the parietal lobe, the occipital lobe and the temporal lobe?
Frontal lobe: Motor function and intellect
Parietal lobe: Somatosensory
Occipital lobe: Vision
Temporal lobe: Hearing and smell
In the brain, where is motor function, sensory function and the limbic system?
Anterior portion of cerebral hemisphere: Motor function
Medial portions of cerebral hemispheres: Limbic system (storage and retrieval of processed information)
Posterior portion: sensory
What is brodmann area 4?
Precentral gyrus - primary motor cortex, somatotopic representation of contralateral half of body (motor homunculus)
What are Brodmann areas 44 and 45?
Inferior frontal gyrus
Broca’s area of motor speech
What is the prefrontal cortex responsible for?
Cognitive functions of higher order- intellect, judgement, prediction, planning.
What are Broddmans area’s 1,2 and 3?
Post central gyrus - primary sensory area
Receives general sensations from contralateral half of body
Where in the brain do the following functions occur?
- Interpretation of general sensory information (sensory association area)
- Conscious awareness of contralateral half of the body
Superior parietal lobule
What is the inferior parietal lobule responsible for?
It is the interaface between the somatosensory cortex and visual and auditory association areas
Contributes to language function in dominant hemisphere
Where is th lesion located that can cause hemisensory neglect?
Parietal lobe lesion
What is the temporal lobe responsible for?
Hearing and smell
Where is the primary auditory cortex? What Broddman areas are these?
Present in the Superior temporal cortex
Brodmanns area 41,42
Where are the auditory association areas (Wernicke’s area)
Posterior to 41,42
In the dominant hemisphere it is known as the Wernicke’s area
What receives fibres from the olfactory tract?
The inferior surface of the temporal lobe - conscious appreciation of smell
What is the importance of Wernicke’s area?
Crucial for understanding of spoken word, has connections with other language areas
Where is the primary visual cortex? What Brodmann number is this?
On the medial surface of the occipital lobe, on either side of the calcarine sulcus is the primary visual cortex (area 17).
Where is the visual association area?
The rest of the occipital lobe is the visual association cortex, (areas 18,19) concerned with interpretation of visual images.
Medial surface of the occipital lobe is the primary visual cortex
Where is the limbic area and what is it responsible for?
Areas of the medial surface of the cerebral hemisphere form a functional limbic lobe
This is involved in memory and emotional aspects of behaviour
What does the limbic lobe consist of?
Cingulate gyrus
Hippocampus (medial aspect of temporal lobe)
Parahippocampal gyrus
Amygdala (subcortical grey matter close to the temporal pole)
What is the motor speech area?
Broca’s area
Wernicke’s is the auditory association area (posterior to the 41,42)
What is the presentation of Broca’s aphasia?
Understands speech Misses small words Aware of difficulties in speech
Damage to frontal lobe
Weakness/paralysis of one side of body
What is the presentation of Wernicke’s aphasia?
Fluent speech, with new meaningless words, can’t understand speech, doesn’t know of mistakes
Damage to temporal lobe
No paralysis
What are the 3 types of myelinated axon fibres?
- Commisural fibres connect corresponding areas of the two hemispheres. (Corpus callosum)
- Association fibres connect one part of the cortex with the other. They may be short or long.
- Projection fibres run between the cerebral cortex and various subcortical centres. They pass through the corona radiata and the internal capsule.
What is the internal capsule made up of?
Projection fibres passing to and from the cerebral cortex
Where is the internal capsule located?
Between the thalamus and caudate nucleus medially and the lentiform nucleus laterally
Where does the internal capsule receive its blood supply?
From the middle cerebral artery and is frequently affected in stroke
What are basal nuclei?
Subcortical nuclei (collection of neuronal cell bodies – grey matter) deep within each cererbal hemisphere.
What comprises the basal ganglia?
Caudate nucleus
Putamen
Globus pallidus
(Substantia nigra in midbrain is functionally part of them though not anatomically.)
What structures form the lentiform nucleus?
Putamen and the globus pallidus
What are the following areas of the brain?
What are the following structures located on the midbrain?
Look
Where does the caudate nucleus and the putamen receive input from?
The motor cortex, pre-motor cortex and from the thalamus
What are the output regions for the caudate nucleus and the putamen?
Globus pallidus and the substantia nigra
What is the direction of fibre travel after the globus pallidus?
1.The globus pallidus then projects primarily to the thalamus (which inturn sends fibres to motor area of cortex)
What is the main function of the basal ganglia?
The major function of the basal ganglia is to help regulate initiation and termination of movements.
Why is the basal ganglia referred to as the extrapyramidal system?
Because they play a role in controlling the motor system
What are pathologies associated with the basal ganglia?
Parkinson’s, chorea, athetosis
What type of mater are basal ganglia?
They are grey matter deep in the white matter of the cortex
