Block 5 - Musculoskeletal and Nervous System 2 Flashcards
What does the cerebellum do?
Coordination and refining of movements by detecting motor errors Motor memory (conscious and unconscious learned movements)
What does the basal ganglia do?
Selection and initiation of voluntary movements
Cognition, attention and working memory
What do the cerebellum and basal ganglia do together?
Increase the accuracy of movements by providing feedback loops to motor and sensory areas in the cortex to modify signals from UMN
What are the two pathways for signals to leave the cerebral cortex by?
Cerebral cortex - Brainstem - Spinal cord - Body - Movement
Cerebral cortex - Basal ganglia + Cerebellum - Thalamus - Cerebral cortex
Where is the cerebellum located?
In the hindbrain underneath the cerebral cortex
What is the structure of the dorsal surface?
What is this called?
Folded
Folia
What does damage of the cerebellum lead to?
Jerky, uncontrolled and inaccurate movements
IPSILATERAL (SAME SIDE)
What does damage of the basal ganglia lead to?
Uncontrolled and decreased movements at rest
What are the 3 parts of the cerebellum?
What do they do?
Where are they found?
Cerebrocerebellum: Inputs from the cerebral cortex; regulated high skilled movements and sequences
(2 SIDES)
Spinocerebellum: Input from the spinal cord
(MIDDLE)
Vestibulocerebellum: Inputs from the vestibular nuclei in the brainstem to coordinate movement, balance and posture. Made from foccules and nodules
(BOTTOM)
How is the cerebellum attached to the pons?
By peduncles
What are the three cerebellar peduncles?
Which pathways are they involved in?
Where do they project to?
Superior cerebellar peduncles: Efferent pathway - Midbrain
Middle cerebellar peduncles: Afferent pathway - Pons
Inferior cerebellar peduncles: Efferent and Afferent - Medulla + Spinal cord
What are two motor input pathways to the cerebellum?
Where do they decussate?
Cerebral cortex - Pontine nucleus (DECUSSATE) Cerebellum
Cerebral cortex - Red nucleus - Inferior olive (DECUSSATE) Cerebellum
What is the sensory input pathway to the cerebellum?
Does this pathway decussate?
Spinal cord/Vestibular nucleus - Inferior cerebellar peduncle - Cerebellum
Does NOT decussate
What is the output pathway from the cerebellum?
Cerebellum - Deep cerebellar nuclei (DECUSSATE in superior cerebellar peduncle) - Thalamus - Primary + premotor cortex
What are the deep cerebellar nuclei?
What do they do?
Output structures in the white matter
Relay corticol cerebellar information to the motor cortex and brainstem as a feedback mechanism to correct movement
What are the 2 output pathway for the vestibulocerebellum?
Fastigial nucleus - Medial descending systems - Motor execution
Vestibular nuclei - Balance and eye movements
What is the output pathway for the spinocerebellum?
Interposed nucleus - Lateral descending systems - Motor execution
What is the difference between lateral and medial descending systems?
Lateral = LIMBS Medial = TRUNK
What is the output pathway for the cerebrocerebellum?
Denate nucleus - Motor + premotor cortex - Motor planning
What are the 2 input pathways to the cerebellum?
Cerebral cortex, spinal cord and vestibular system –> Mossy fibres which synpase onto granule cells –> Parallel fibres which synapse with purkinje fibres
Inferior olive –> Climbing fibres which synapse with purkinje fibres
What is the output pathway from the cerebellum?
Purkinje fibres synapse onto neurones in the deep cerebellar nuclei –> GABA –> Thalamus and motor cortex
What are the interneurones in the cerebellum?
Granule, Satellite, Golgi and Basket cells
What happens if there is a lesion in the vestibulocerebellum?
Damage to balance and eyes
What happens if there is a lesion in the spinocerebellum?
Impaired gait and decreased smoothness of movement
What happens if there is a lesion in the cerebrocerebellum?
Impairments in highly skilled sequences
What is sent to sensory neurones before you tickle yourself?
An efference copy
What does alcohol degenerate in the cerebellum?
Which limbs are affected?
The anterior cerebellum
Lower limbs affected
What is cerebellar ataxia?
Jerky, imprecise and uncoordinated movements
What is Dyssynergia?
Patients move joints separately, not simultaneously
What is Dysmetria?
The inability to judge distance
What is Dysdiadochokinesia?
You can’t do rapid, alternating movements
What is an intention tremor?
A tremor when you’re moving
What is ataxicdysarthria?
Slurred speech
Where is the basal ganglia?
What is it?
Underneath the cerebral cortex but outside the thalamus
A collection of functionally distinct nuclei
What is the input zone to the basal ganglia?
Caudate nucleus and putamen –> Striatum
What is the output zone to the basal ganglia?
Globus Pallidus and substantia nigra –> Pars Reticula
What excites and inhibits the basal ganglia?
Excities: Glutamate from the motor cortex
Inhibits: Basal ganglia and feedback mechanisms
What are the three input pathways to the Basal Ganglia?
What neurotransmitter is involved with 2 of them?
Corticostriatal pathway: Cerebral cortex –> Striatum (Glutamate)
Nigrostriatal pathway: Substantia Nigra –> Striatum (Dopamine)
Medium spiny neurones: Inputs to the striatum
What are the two output pathways from the basal ganglia?
Striatum - Substantia Nigra - Superior colliculus - Eye movements
Striatum - Globus pallidus - limb and trunk movements - thalamus - motor cortex
What does the globus pallidus do to the thalamus?
What does this mean for movement?
Globus pallidus inhibits the thalaus causing decreased excitation of the motor cortex and decreased movement
What happens when the substantia nigra release dopamine and it binds to D1 in the striatum?
What pathway is this?
Removes inhibition of the globus pallidus
Thalamus excites the motor cortex
Movement occurs
DIRECT PATHWAY
What 2 things happen when the substantia nigra release dopamine and it binds to D2 in the striatum?
What pathway is this?
Decreases inhibition on the globus pallidus causes increased inhibition of the thalamus
Decreased inhibition of the subthalamic nucleus leads to increased excitation of the subthalamic nucleus and increased inhibition of the thalamus
Thalmus sends no signal to the motor cortex causing no movement
INDIRECT PATHWAY
2 causes of Parkinson’s disease?
Idiopathic
Genetic
What type of disorder is Parkinson’s?
4 symptoms?
Hypokinetic (can't initiate movement) T: Tremor of hands R: Rigidity of muscles A: Akinesia (no movement) P: Postural problems