The Cerebral Hemispheres Flashcards
What are the general features of the cerebral hemispheres?
- Sulci
- Gyri
- Fissures
- Grey matter on the surface
- White matter inside
- Basal ganglia: collection of neuronal cell bodies buried in white matter
- Lateral ventricle
Sulcus
Dip
Gyrus
Elevation
Fissure
Large dip
What fissure runs sagittally in the midline?
Median longitudinal fissure
What connects the 2 cerebral hemispheres?
Corpus callosum
What sulcus lies between the frontal and parietal lobes?
Central sulcus
What 2 gyri sit either side of the central sulcus?
- Precentral gyrus
- Postcentral gyrus
What sulcus lies between the parietal and occipital lobes?
Parieto-occipital sulcus
What sulcus runs on the medial side of the hemispheres following the course of the corpus callosum?
Cingulate sulcus
What gyri are found in the frontal lobe?
- Superior frontal gyri
- Middle frontal gyri
- Inferior frontal gyri
What gyri are found in the temporal lobe?
- Super temporal gyri
- Middle temporal gyri
- Inferior temporal gyri
What is the insula?
Small region located deep within the lateral sulcus
What area of the cerebral hemisphere is responsible for sensory components ?
Posterior part
What area of the cerebral hemisphere is responsible for motor components?
Anterior part
What are medial parts of the cerebral hemispheres responsible for?
Storage and retrieval of processed information
What is often found adjacent to primary sensory areas?
Association areas
What is area 4?
Precentral gyrus
-Primary motor cortex
What is the primary motor cortex responsible for?
Somatotopic representation of contralateral half of body (motor homunculus)
What are areas 44 and 45?
Inferior frontal gyrus
-Broca’s area of motor speech
What is the function of the prefrontal cortex?
Cognitive functions of higher order
- Intellect
- Judgement
- Prediction
- Planning
What are the components of the motor homunculus from lateral to medial aspect?
- Swallowing
- Tongue
- Jaw
- Lips
- Face
- Eye
- Brow
- Neck
- Thumb
- Fingers
- Hand
- Wrist
- Elbow
- Arm
- Shoulder
- Trunk
- Hip
- Knee
- Toes
What are the components of the sensory homunculus from lateral to medial aspect?
- Intra abdominal
- Pharynx
- Tongue
- Gums
- Teeth
- Lips
- Face
- Nose
- Eye
- Thumb
- Fingers
- Hand
- Forearm
- Elbow
- Arm
- Head
- Neck
- Trunk
- Hip
- Leg
- Toes
- Genitals
What are areas 3,2 and 1?
Post-central gyrus
-Primary sensory area
What is the primary sensory area responsible for?
Receives general sensations from contralateral half of body. Somatotopic representation (sensory homunculus)
What is the superior parietal lobule responsible for?
Interpretation of general sensory information (sensory association area) and conscious awareness of contralateral half of body
What is the inferior parietal lobule responsible for?
Interface between somatosensory cortex and visual and auditory association areas.
What is the inferior parietal lobule responsible for in the dominant hemisphere?
Contributes to language functions
What will a parietal lobe lesion result in?
- Hemi sensory neglect
- Right left agnosia
- Acalculia
- Agraphia
What are the main functions of the temporal lobe?
- Hearing
- Smell
What are areas 41 and 42?
Superior temporal gyrus
-Primary auditory cortex
Where are the auditory association areas located?
Posterior to areas 41 and 42
What is Wernicke’s area?
Auditory association area necessary for recognition of the spoken word. Located in the dominant hemisphere
What does the inferior surface of the temporal lobe receive?
Receives fibres from olfactory tract- conscious appreciation of smell
What is the main function of the occipital lobe?
Vision
What is area 17?
Primary visual cortex
Where is the primary visual cortex located?
On the medial surface of the occipital lobe, on either side of the calcarine sulcus
What are areas 18 and 19?
Visual association cortex concerned with interpretation of visual images
What forms the functional limbic lobe?
The medial surface of the cerebral hemisphere
What does the functional limbic lobe include?
- Cingulate gyrus
- Hippocampus (medial aspect of temporal lobe)
- Parahippocampal gyrus
- Amygdala (subcortical grey matter close to temporal pole)
What is the motor speech area?
Broca’s area
Aphasia
Problem with speech due to damage to one or more speech areas in the brain
What area is necessary for recognition of spoken work?
Wernicke’s area
How does Broca’s aphasia present?
- Understands speech -Misses small words -Aware of difficulties in speech
- Damage to frontal lobe
- Weakness/paralysis of one side of body
How does Wernicke’s aphasia present?
- 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 bundles into tracts?
- Commissural fibres
- Association fibres
- Projection fibres
What do commissural fibres connect?
Connect corresponding areas of the 2 hemispheres (Corpus callosum)
What do association fibres connect?
Connect one part of the cortex with the other. They may be short or long
What do projection fibres connect?
Run between the cerebral cortex and various subcortical centres. They pass through the corona radiata and the internal capsule
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 stunningin vivolocalisation of short and medium-length neural tracts, which was previously impossible
What is the internal capsule made up from?
Projection fibres passing to and from the cerebral cortex
What is the internal capsule?
A narrow area between the thalamus and caudate nucleus medially and the lentiform nucleus laterally
What is the blood supply to the internal capsule?
Middle cerebral artery
-Frequently affected in a stroke
What are the basal ganglia?
Subcortical nuclei (collection of neuronal cell bodies – grey matter) deep within each cererbal hemisphere.
What are the components of the basal ganglia?
- Caudate nucleus
- Putamen
- Globus pallidus
What structure is functionally part of the basal ganglia but not anatomically?
Substantia nigra of the midbrain
How are the individual basal ganglia identified?
Caudate: The one with the tail
The Putamen – (which actually means the hard shell)
Globus pallidus: The pale globe
Lentiform nuclues:The hard shell + the globe form a lens like structure
Substantia nigra: The black substance (this lies in the midbrain!)
The subthalamic nucleii
What is lateral to the internal capsule?
Lentiform nuclues
What is medial to the internal capsule?
Caudate nucleus
Describe the structure of 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
What are the input regions of the basal ganglia?
Caudate nucleus and the putamen
Where do the caudate nucleus and putamen receive input from?
- Motor cortex
- Premotor cortex
- Thalamus
What are the output regions of the basal ganglia?
Globus pallidus and the substantia nigra
Where does the globus pallidus primarily project to?
To the thalamus (which in turn sends fibres to motor area of cortex)
What is the major function of the basal ganglia?
Help regulate initiation and termination of movements
What ‘system’ are the basal ganglia often referred to as?
Extrapyramidal system
Give examples of pathology affecting the basal ganglia.
- Parkinson’s
- Chorea
- Athetosis
What is the functional limbic lobe involved in?
Memory and emotional aspects of behaviour
