The Cerebral Hemispheresebral Hemispheres Flashcards
What is a dip in the cerebral hemisphere called?
sulcus
What is a elevatino in the cerebral hemisphere called?
gyrus
What is a larger dip in the cerebral hemisphere called?
fissure
In the cerebellum a elevation is not called a gyrus, what is it instead?
folia
What is the cavity called in each cerebral hemisphere?
lateral ventricle
What is the collection of neuronal cell bodies buried in white matter in the cerebral hemisphere called?
basal ganglia
What matter in on the outside surface of the cerebral hemisphere and what is on the inside?
grey matter on the outer surface and white matter on the inner surface
What is A?
Median longitudinal fissure
What is B?
Corpus callosum
Where and what is the corpus callosum?
Deep inside longitudinal fissure you have a bridge called the corpus collosum which is made of myelinated axons, allows the 2 hemispheres to talk to each other
a
frontal lobe
b
parietal lobe
c
temporal lobe
d
occipital lobe
e
lateral sulcus
f
central sulcus
g
precentral gyrus
h
postcentral gyrus
a
Cingulate sulcus (and gyrus)
b
Parieto-occipital sulcus
c
Corpus callosum - connects the 2 hemispheres
d
Hippocampus
What is the hippocampus?
Small bit of the temporal lobe is called the hippocampus which is on the medial side
a
Superior frontal gyrus
Middle frontal gyrus
Inferior frontal gyrus
b
Superior & inferior parietal lobule
c
Superior, middle and inferior temporal gyri
Where in the insula?
Insula is a hidden part of the temporal lobe in the lateral sulcus
How is cortical mapping done?
split into 52 different areas
each numbered area applies to different functional regions
What is the frontal region of the cortex for?
motor function
intellect
What is the parietal region of the cortex for?
somatosensory
What is the occipital region of the cortex for?
vision
WHat is the temporal region of the cortex for?
hearing and smelling
What part of the cerebral hemisphere is for sensory and what part for motor?
Posterior part of the cerebral hemisphere is sensory while the anterior part is motor
What are the medial portions of the cerebral hemispheres for?
Medial portions of the cerebal hemisphere (limbic system) – storage and retrieval of processed information
Is one hemisphere more dominant?
Yes
Dominant and non-dominant hemisphere
On the brain stem, what side are motor and sensory fibres?
motor - anterior - ventral
sensory - posterior - dorsal
What is area 4 of the frontal lobe (motor)
Area 4: Precentral gyrus – Primary Motor cortex – somatotopic representation of contralateral half of body (motor homunculus)
Whata re areas 44 and 45 of the forntal lobe?
Inferior frontal gyrus: Broca’s area of motor speech (area 44,45)
What does your prefrontal cortex do?
Prefrontal cortex – cognitive functions of higher order- intellect,judgement, prediction,planning
This shwos the role of the precentral and postcentral gyrus
What are area 3, 1, 2 of the brain?
Post-central gyrus: Areas 3,1,2 – Primary sensory area. Recieves general sensations from contralateral half of body. Somatotopic representation (sensory homunculus)
What does the superior parietal lobule do?
Superior parietal lobule: Interpretation of general sensory information (sensory association area) and conscious awareness of contralateral half of body
What does the inferior parietal lobule do?
Inferior parietal lobule: Interface between somatosensory cortex and visual and auditory association areas
In dominant hemisphere, contributes to language functions
What can a parietal lobe lesion lead to?
Hemisensory neglect - neglect of one side of the body
Right-left agnosia
Acalculia - loss of the ability to perform simple calculations
Agraphia - loss in the ability to communicate through writing
What are areas 41 and 42 in the superior temporal gyrus
primary auditory cortex
What are where are the auditory association areas?
Auditory association areas – posterior to 41,42. Only in the dominant hemisphere – Wernicke’s area. Crucial for understanding of spoken word. Has connections with other language areas
What does the inferior surface of the temporal lobe do?
recieves fibres from olfactory tract - concious appreciation of smell
What makes up the occipital lobe and its function?
On the medial surface of the occipital lobe, on either side of the calcarine sulcus is the primary visual cortex (area 17)
The rest of the occipital lobe is the visual association cortex, (areas 18,19) concerned with interpretation of visual images
What is the limbic lobe?
The medial surface of the cerebral hemisphere has areas which together form a functional limbic lobe involved in memory and emotional aspects of behaviour.
It includes the cingulate gyrus, the hippocampus (medial aspect of temporal lobe), parahippocampal gyrus, and the amygdala (subcortical grey matter close to temporal pole)
WHat are the language areas of the brain?
Broca’s area is the motor speech area.
Wernicke’s area is the auditory association area necessary for recognition of the spoken word. Is in the dominant hemisphere
What is aphasia?
problem with speech due to damage to one or more speech areas in brain
What would happen in Brocas aphasia?
Understands speech but misses small words and is aware of difficulties in speech
Damage to frontal lobe
Weakness/paralysis of one side of body
What would happen in Wernickes aphassia?
Fluent speech, with new meaningless words, can’t understand speech, doesn’t know of mistakes
Damage to temporal lobe
No paralysis
How many types of white matter are there?
there are 3 types of myelinated axon fibres bundled into tracts
What are the 3 types of white matter?
Commisural fibres
Association fibres
Projection fibres
What are commisural fibres
connect corresponding areas of the two hemispheres (Corpus callosum)
What are association fibres?
connect one part of the cortex with the other
They may be short or long
What are projection fibres?
Run between the cerebral cortex and various subcortical centres
They pass through the corona radiata and the internal capsule
Both afferent and efferent nerve fibers that couple the brain with the spinal cord
What is 3D cerebral tractography?
Tractography is a recent 3D modelling technique that maps functional white matter tracts using data collected using magnetic resonance imaging (MRI). Based on symmetry of brain water diffusion, this method offers visually stunning in vivo localisation of short and medium-length neural tracts, which was previously impossible
Where is the internal capsule?
It is a narrow area between the thalamus and caudate nucleus medially and the lentiform nucleus laterally
What is the internal capsule?
mad eup of projection fibres passing to and from the cerebral cortex
Everything form cerebral hemispheres and spinal cord has to go through here
it recieves blood supply from the middle cerebral artery and is frequently affected by strokes
What is the basal ganglia?
Subcortical nuclei (collection of neuronal cell bodies - grey matter) deep within each cererbal hemisphere
What makes up the basal ganglia?
Made up of the caudate nucleus, putamen and globus pallidus
Substantia nigra in midbrain is functionally part of them though not anatomically
The individual basal ganglia - what is the one with the tail?
caudate
The individual basal ganglia - what one means hard shell?
putamen
The individual basal ganglia - what is the pale globe?
globus pallidus
The individual basal ganglia - what is the putamen + the globus pallidus
lentiform nucleus
The individual basal ganglia - what is the black line seen in the midbrain?
substantia nigra
a
caudate nucleus
b
putamen
c
globus pallidus
d
thalamus
e
lentiform nucleus
f
substantia nigra
Where is the caudate nucleus?
The caudate nucleus starts as a large head medial to the internal capsule, a body and a slender curving tail which follows the curve of the lateral ventricle
Where is the lentiform nucleus?
Lateral to the internal capsule is the lentiform nucleus made up of the putamen laterally and globus pallidus medially
What is the process fo determing the grey mater in the brain?
- Identify the lateral ventricles and third ventricle (if present in the section)
- Lying in the wall of the lateral ventricle is the caudate nucleus
- Lying beside the third ventricle is the thalamus (diencephalon)
- Lateral to the caudate and thalamus lies the internal capsule
- Lateral to the internal capsule is the lentiform nucleus made up of the globus pallidus medially and putamen laterally
What are the ocnnections of the basal ganglia?
- The caudate nucleus and the putamen are the ‘input regions’ receiving input from the motor cortex, premotor cortex, and from thalamus
- They are in turn connected to the output regions – the globus pallidus and the substantia nigra
- The globus pallidus then projects primarily to the thalamus (which inturn sends fibres to motor area of cortex)
What does the basal ganglia do?
The major function of the basal ganglia is to help regulate initiation and termination of movements.
Because they play a role in controlling the motor system they are often referred to as the “extrapyramidal system”
What are some pathologies affecting the basal ganglia?
Pathology: Parkinson’s, chorea, athetosis etc
