Neuro Anatomy 3 - Basal Ganglia and Cerebellum Flashcards
What is the name of either of the 2 masses of grey matter lying between the cerebral hemispheres on either side of the third ventricle?
Thalamus
What is the thalamus important for?
Relaying sensory information to the cortex and acting as a centre for pain perception (acts as the gate-keeper)
Does the primary motor area plan movement alone?
No - has a large amount of input from other areas of the brain which pre-plan the movement
What is the name of the group of subcortical nuclei situated at the base of the forebrain?
Basal ganglia
3 main functions of the basal ganglia?
To facilitate purposeful movement
Inhibit unwanted movements
Role in posture and muscle tone
What role does the cerebellum have in movement?
Co-rodinates movement by using sensory information to make fine-adjustments to motor movements
Also important in motor memory
What area of the brain plans movement?
Motor cortex
Describe how the motor cortex, cerebellum, basal ganglia and thalamus interact to cause a movement?
Motor cortex initiates movement
Cerebellum adjusts movement using sensory information sending information about altered movement back to the motor cortex and makes adjustments to the movement directly
Info from cerebellum to cortex is sent via the thalamus (acts as gate-keeper for sensory information)
Basal ganglia further controls movement by aiding, dampening or stopping movement
What are the names of the 3 lobes of the cerebellum?
Anterior lobe
Posterior lobe
Flocculonodular lobe
what is the flocculonodular lobe of the cerebellum made up of?
Flocculus
Nodule
What is the name of the fissure between the anterior and posterior lobe of the cerebellum?
Primary fissure
What is the name of the fissure in the posterior lobe of the cerebellum?
Horizontal fissure
What part of the cranial fossa does the cerebellum sit in?
Posterior cranial fossa
What is the name of the extension of the dura mater above the cerebellum?
Tentorium cerebelli
What is the name of the extension of the dura mater which extends longitudinally between the hemispheres of the cerebrum?
Falx cerebri
What is the name of the extension of the dura mater which extends longitudinally between the cerebellum?
Falx cerebelli
Is the core of the cerebellum white or grey matter?
Core = white matter with extensive surrounding grey matter (some grey matter curried in at the core)
What is another name for stalk (as in the stalks that attach the cerebellum to the brainstem)?
Peduncles
What is the name for the 3 stalks which attach the cerebellum to the brainstem?
Superior cerebellar peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle
Name for the midline of the cerebellum?
Vermis (hemispheres at either side)
What structures make up the deep grey matter of the cerebellum?
Deep cerebellar nuclei
Name of the 3 layers of the cerebellar cortex?
Molecular layer (outer)
Purkinje cell layer (middle)
Granule cell layer (inner)
Which layer of the cerebellar cortex contains many tiny neurones?
Granule cell layer
Which layer of the cerebellar cortex contains giant cell nuclei?
Purkinje cell layer
What are the 3 main important afferents from to the cerebellum?
Spinal cord, from somatic proprioceptors and pressure receptors
Cerebral cortex (relayed via the pons)
Vestibular apparatus via the vestibular nuclei
How does afferents enter the cerebellum and where does it project to?
Cerebellar peduncles
Granule cell layer
What is the only output of the cerebellum via?
Axons of purkinje cells which mainly synapse on neurones of the deep cerebellar nuclei
Where do efferent axons from the deep cerebellar nuclei in the cerebellum go?
Cross the midline and synapse in the thalamus which in turn sends fibres to the motor cortex
What side of the body does a cerebellar lesion affect?
Ipsilateral side (cerebellar hemispheres influence the ipsilateral side)
Effect of a unilateral hemispheric lesion?
Disturbance of co-ordination in limbs and unsteady fait (absence of weakness or sensory loss)
Effect of bilateral cerebellar dysfunction?
Results in slowed, slurred speech (dysarthria), bilateral incordination of the arms and a staggering, wide based gait (cerebellar ataxia)
Effect of midline cerebellar lesion?
Disturbance of postural control
3 functional regions of the cerebellum?
Vestibulocerebellum
Spinocerebellum
Pontocerebellum
What are the 5 named masses of grey matter which make up the basal nuclei?
Caudate nucleus Putamen Globus pallidus Subthalamic nucleus Substantia nigra
Name of the putamen + globus pallidus?
Lenticular nucleus
Name of the caudate nucleus + putamen?
Striatum
Name of the striatum + globus pallidus?
Corpus striatum
What is the name of the 2 stripes of the globes pallidum?
Lateral and medial stripe
Which of the masses of grey matter in the basal ganglia curves round the lateral ventricle?
Caudate nucleus
In what disease are the cells of the substantial nigra lost?
Parkinsons disease
Which of the grey matter structures in the basal ganglia are self-stained black?
substantia nigra
What causes parkinsons disease?
Degeneration of dopaminergic neurones of the substantia nigra
What are the names of the 2 pathways in the basal ganglia which enhance or inhibit the activity of the motor cortex?
Direct/ indirect pathway
What effect does the direct pathway have on the activity of the motor cortex?
Enhances it - increases movement
Does the direct pathway in the basal ganglia excite or inhibit the thalamus?
Excites (through a decrease in inhibitory signal) leading to further excitation of the motor cortex
Which component of the basal ganglia is involved in the indirect but not direct motor pathway?
Globus pallidus externus
What effect does the indirect pathway have on the thalamus?
Inhibits outflow of thalamus = decreased activity of motor cortex
Do unilateral lesions of the basal ganglia affect the ipsilateral or contralateral side of the body?
Contralateral side
What motor signs do lesions of the basal ganglia cause?
Changes in muscle tone
Dyskinesias (abnormal, involuntary movements) i.e. tremor, chorea
Myoclonus (muscle jerks)
Describe chorea movements?
Rapid, asymmetrical movements usually affecting distal limb musculature
What are 2 disorders associated with the basal ganglia?
Parkinson’s disease
Huntington’s disease (huntington’s chorea)
What is the pathology behind Huntington’s disease?
Degeneration of dopaminergic neurones of the substantia nigra
What are 3 signs of parkinson’s disease?
akinesia
Rigidity
Resting tremor
Describe the genetics of huntington’s disease?
Autosomal domiannt disorder
Describe the pathology of huntington’s disease?
Progressive degeneration of the basal ganglia and cerebral cortex
What are 2 signs of huntington’s disease?
Chorea
Progressive dementia