W5: Brain And Control Of Movements 2 Flashcards
Overview of the sensorimotor system that generates controlled movements
- neurones of the brainstem are largely responsible for descending inhibition of LMNs
- cerebral cortex makes an instruction for a movement to be carried out. It issues commands to the basal ganglia and cerebellum
- basal ganglia encodes the instructions and sends to the thalamus
- cerebellum also receive a signal from the cerebral cortex and checks whether there are template movements that can be repeated, sending a contribution to the thalamus
- thalamus organises info and feeds back to the cerebral cortex which will give out the final command
- cerebellum also feeds signals to the brainstem
- descending tract systems will bring outputs towards LMNs which will give rise to muscle contractions
What do lower motoneurones connect to?
Their axon crosses the CNS into the PNS and directly activates muscles via the NMJ
Which tracts are pyramidal?
Corticospinal (and corticobulbar)
What are basal ganglia?
Sub-cortical nuclei of the telencephalon (of the brain, fairly high up)
What do the basal ganglia do?
Play a crucial role in the generation and control of planned movement, regulating the amplitude and velocity of planned movement. Particularly in relation to proprioceptive information. Gives output to the thalamus.
What are significant nuclei of the basal ganglia?
Caudate nucleus, putamen, globus pallidus, subthalamic nucleus
Is the basal ganglia part of the limbic system?
Yes
What do diseases of the basal ganglia result in?
Generation of unwanted movement
Failure of the brain to initiate movements (brings about bradykinesia)
What is Parkinson’s disease?
Neurological disorder of the doperminergic neurones of the basal ganglia. Has elements of unwanted movement (resting tremor) and difficulty initiating movement (bradykinesia). Has the UMN sign of hypertonia.
What is Huntington’s disease?
Autosomal dominant condition where you have progressive functional loss of cholinergic and GABA-regicide neurones in the striatum of the basal ganglia.
What symptoms are displayed in huntingtons disease?
Involuntary jerking movements. Later accompanies by dementia. Disease of hyperkinesia.
What is hemiballismus?
Affected patients generate violent flings of extremities of the upper or lower limbs. Involuntary movements usually in a rotating manner. Caused by damage to the subthalamic nucleus of the basal ganglia.
What does the cerebellum do in the control of movements?
It receives instructions from the cerebral cortex that movements are being carried out. Relays its signals to the brainstem. Also receives direct output from the sensory systems of the brain which help it to upstate itself of the state of senses for the execution of movements.
Does the cerebellum initiate movements?
It does not initiate movements. It contributes to coordination, precision and accurate timing. It receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity.
What are the functional zones of the cerebellum? LOOK AT PIC
Vestibulocerebellum (flocculonodular) - main input from vestibular system, involved in balance and ocular reflexes
Spinocerebellum- involves in error correction
Cerebrocerebellum - involved in movement
