Control of Movement 3 Flashcards
What are the three layers if the cerebellum?
Molecular Layer
Purkinje cell layer
Granule cell layer
What is the function of granule cells in the cerebellum?
Make interconnections, can act as transporters and integrators of information from the granular layer up to the molecular layer
What is the function of stellate cells?
Small cells, distributing information on a more ‘local’ level
What is the function of parallel fibres (from granule cell)?
Move information throughout layers in a linear fashion (between Purkinje cells)
What is the function of basket cells?
Form a basket like structure around Purkinje cells
What is the function of mossy fibres?
Input
One of the main sensory inputs
Terminate in the granule later where they spread around their information to other cells
What is the function of the climbing fibres?
Input specifically from olives
Come from the olives and ‘climb up to’ the molecular later where they wrap themselves around the dendrites
Important in learning about movements for improvement on correction of motor output
What inputs arrive at the vestibular system?
- Inputs from vestibular nuclei (balance) project to the vestibulocerebellum (flocculonodular lobe) and vermis
- The flocculonodular is involved with maintaining balance and posture
What inputs arrive for proprioceptive feedback?
- Inputs from ascending sensory spinal pathways derived principally from proprioceptors to the spinocerebellum (= Anterior lobe + Vermis + Intermediate vermis)
- The spinocerebellum modulates axial or antigravity muscles and eye movement
- The spinocerebellum contains a somatotopical map of the body
What inputs arrive for cortical input?
- Inputs from the motor and pre-motor cortex as well as somatosensory cortex via multiple pontine nuclei project to the cerebrocerebellum
- The cerebrocerebellum is involved with motor planning, and feeds information back towards the cerebra
- Functions to sequence and coordinate distal muscles esp. during locomotion or juggling etc.
What is the flocculonodular involved in?
Involved with maintaining balance and posture
What is the spinocerebellum involved in?
Modulates axial or antigravity muscles and eye movement
Contains a somatotopical map of the body
What is the cerebrocerebellum involved in?
Involved in motor planning, and feeds information back towards the cerebra.
Functions to sequence and coordinate distal muscles
Name the deep nuclei of the cerebellum from lateral to medial.
Dentate nucleus
Emboliform nucleus
Globose nucleus
Fastigial nucleus
What are the outputs of the fastigial nuclei?
- Medial descending systems (trunk and proximal via reticular formation)
- Vestibular nuclei, tectum and cranial nerve nuclei
What nuclei are involved in motor execution?
Fastigal nuclei
Interposed nuclei
What is the output of the interposed nuclei?
- Lateral descending systems (distal and extremities via spindles)
What is the output of the dentate nuclei?
- Motor and premotor cortices
What nuclei are involved in motor planning?
Dentate nuclei
What nuclei are involved in head and eye movements?
vestibular, Tetum and cranial nerve nuclei
What is flocculonodular lobe syndrome?
Not common
Seen in children with medulloblastoma
Characterised by truncal ataxia, wide based stance and swaying.
In general terms, what do medial cerebellar lesions affect?
Medial descending pathways, causing unsteady gait (truncal ataxia), problems with balance, posture and eye movement abnormalities (nystagmus)
What do lateral cerebellar lesions affect?
Affect control of distal muscles and motor planning.
Results in limb ataxias.
What do lesions of the cerebrocerebellum cause?
- Delay in initiation of movement
- Decomposition of multi-joint movements (e.g. loss of complex motor skills)
What do lesions of the intermediate lobe (spinocerebellum) cause?
Affect distal muscles and cause limb ataxia and action tremor
What do lesions of the vermis (spinocerebellun) OR fastigial nucleus cause?
Affect axial and trunk muscles
Makes balance unsteady (wide stance)
Where is information from the vestibular nuclei passed to?
The Flocculonodular lobe or vestibulocerebellum and the vernal/paravermal areas
What does olivary information enable?
The calculation of predicted posture in advance of it happening so feed forward posture adjustments allows fast postural changes
What are the pre and primary motor cortex and somatosensory cortex via?
Pontine nuclei and middle peduncle
Describe the process of sequencing and timing complex movements.
- Pre motor and sensory areas in the cortex begin to plan for a complex movement
- The plan is transferred to the lateral lobes of the cerebellum (cerebrocerebellum) via pontine nuclei
- Output concerning the order and timing of the movements is routed through the dentate nucleus and back via the thalamus to the cortex
Describe anterior lobe syndrome.
Planned and actual motor output are compared and corrective signals sent via the thalamus. Errors in corrective signals from cerebellum. Includes overshoot (dysmetria), intention tremor and lack of movement dampening
