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Cerebellum.
Week1.Brain Functional Anatomy
| Question | Answer |
|---|---|
| Cerebellum means.. | Little brain, only acounting for about 10% of brain mass BUT having basically the same number of neurons as all the rest of the CNS |
| Sensory inputs.. | Basically every sensory input finds its way into the cortex of the cerebellum some way or another, then is projected to deep cerebellar nuclei and from there to the thalamus and the brainstem. |
| Lesions.. | Generally result in abnormalities of equilibrium,postural control and coordination of voluntary movements.These are considered motor disturbances and so, despite cerebellum having few direct influences on motor neurons,it's considered part of motor system |
| Folia | The cortical ridges/folds are referred to as folia meaning 'leaf', in relation to the analogy of the sagittal section appearing like a tree.. arbor vitae, meaning 'tree of life' |
| What is the first fissure to appear during development | Posterolateral fissure |
| Posterolateral fissure | Separates, almost pinching off the flocculonodular lobe (flocculi+nodule) from the body of the cerebellum (sometimes referred to as the 'corpus cerebelli'). This is continuous with horizontal fissure |
| Generally responsible for.. | unconscious control of movement and position in space (close links with vestibular system) and is also involved in learning motor sequences even quite complicate ones, when those motor sequences become automatic, that's when they become cerebellar. |
| Anterior Lobe | Contains the lingula and is separated from the posterior lobe by the primary fissure |
| Lingula | A thin piece of cerebellum lying on the superior surface of the superior medullary velum |
| Superior cerebellar peduncle | Has few afferents into the anterior lobe however,it is predominantly efferent & is the largest output pathway of the cerebellum.The pathway goes under the IC and terminates in the red nucleus.The 2 pathways passing through are important for motorplanning |
| Middle Cerebellar Peduncle | Completely input pathway, ie afferent originating from pontine nuclei.It is the largest of the three peduncles receiving fibres from sensory and motor areas. |
| Inferior Cerebellar Peduncle | Input & output fibres. Integrates proprioceptive sensory info & motor vestibular functions.Info goes from body to cerebellum via spinocerebellar tract.Info synapses in paleocerebellum & archicerebellum.Also carries info from purkinje to vestibular nuclei |
| Cerebellar Nuclei | Fierce Gorillas Eat Dentists Most medial - Fastigial, Globose, Emboliform and Dentate Nuclei Each nucleus is associated with a particular lobe. |
| Hilus of the Dentate Nucleus | Is the mouth of the dentate nucleus These fibres running out of the mouth (like a vomiting dentate nucleus) go to the Superior Cerebellar Peduncle |
| Interposed Nucleus | Collective term for the Globose and Emboliform Nucleus |
| Vestibular Nuclei | Main site of termination is the flocculonodular lobe |
| Juxtarestiform Body | Is apathway & part of ICP.Its close to the trigeminal complex & conveys sensory information in relation to face to cortex.It also connects the vestibular nuclei to cerebellum.This body lies next to "juxtpose" both trigeminal complex & vestibular nuclei |
| Inferior Olivary Complex | Projects up to the cerebellum via 'Climbing Fibres' and has STRONG input into Purkinje Cells which span the WHOLE of the cerebellum. Essential for learning and adjusting movements. |
| Climbing Fibres | Projections from the Inferior Olivary Complex to the Purkinje Cells of the Cerebellum. Vital for learning and adjusting movements. If these fibres are lesioned, no new learning or adjustments can occur, e.g. like the conditioned blinking reflex. |
| Inferior Olivary Inputs.. | Afferents leave the hilus of the inferior olivary nucleus and CROSS THE MIDLINE via the internal arcuate fibres, then enters the CONTRALATERAL cerebellum via ICP. |
| Higher order processing unit | It receives 20million axons but only sends out 2 million.. the cerebellum is CLEARLY and intergrative higher processing unit. |
| Functional Organisation of the Cerebellum | Vestibuocerebellum (Archicerebellum) Spinocerebellum (Paleocerebellum) Cerebrocerebellum (Neocerebellum) |
| Vestibulocerebellum/Archicerebellum(functions and control) | Controls unconscious movements & maintains position in space.Does this by controlling axial muscles of body to maintain balance & posture,controls neck muscles for head movements & extrinsic eye muscles 4 coordinated eyemovements-vestibular occular reflex |
| Horizontal Fissure | Divides the Posterior lobe into inferior and superior aspects, the ends of the horizontal fissure come together to the posterolateral fissure. |
| Vestibulocerebellum/Archicerebellum (dysfuntion) | Feelings of vertigo, instability and wide based gait arises. Head is often tilted nystagmus is commonly seen experienced. |
| Vestibulocerebellum/Archicerebellum (consists of) | Flocculi, the uvula and the fastigial nucleus |
| Spinocerebellum/paleocerebellum (functions) | to adjust/control body movements (postural adjustments) and eye movements in response to sensory inputs - via the vermis (though it is more closely related to the vestibulocerebellum and axial muscle control) |
| Spinocerebellum/paleocerebellum (controls) | Controls limbs for execution of Smoooooth movements and smooth coordination & execution of motor tasks and correction of errors - via paravermis |
| Spinocerebellum/paleocerebellum (dysfunction) | Ataxia arises i.e. lack of control over movements, dysarthia i.e. inability to speak clearly and intention tremor i.e. movements aren't fine tuned and corrected resulting in tremors when reaching out or performing movements. |
| Spinocerebellum/paleocerebellum (consists of) | Vermis projecting to fastigial nucleus Paravermis projecting to globose & emboliform |
| Vestibulocerebellum/archicerebellum (inputs) | Vestibular ganglion and vestibular nucleus via JRB of ICP |
| Vestibulocerebellum/archicerebellum (outputs) | From fastigial nucleus, projections go to vestibular nuclei then to reticular nucleus, vestibulospinal tract and occulomotor nucleus. |
| Spinocerebellum/paleocerebellum (inputs) | Proprioceptive and somatosensory info from body (via dorsal and ventral spinocerebellar tracts; ICP and SCP) and head (via principal sensory n. of trigeminal and spinal trigeminal n.; ICP) as well as auditory and vestibular input |
| Spinocerebellar vermis outputs | To fastigial nucleus, then that projects to VA/VL of the thalamus ans lateral vestibular n. |
| Spinocerebellar paravemis outputs | To globose and emboliform n. which mainly thne project to red nucleus via SCP and also VA/VL of thalamus. |
| Cerebrocerebellum/Neocerebellum (functions) | responsible for: Unconscious initiation, PLANNING and timing of precise movements. Controls Voluntary gaze, saccades and hand-eye coordination It plays a big role in INITIATION of movements for tasks such as eating, dressing and writing |
| Cerebrocerebellum/neocerebellum (controls) | Controls trajectory, velocity and accelerationg of movements e.g. picking up a cup which involves figuring out what to do BEFORE doing it. Whereas spinocerebellar is for DURING movement when controls are exercised. |
| Cerebrocerebellum/neocerebellum (dysfunction) | Similar to that of spinocerebellum in that dysarthia and ataxia is observed. Particularly characteristic of dysfunction is difficulties INITIATING and TERMINATING movements and POOR hand-eye coordination is also experienced by the patient. |
| Cerebrocerebellum/neocerebellum (consists of) | Cerebellar hemispheres and dentate nucleus |
| Cerebrocerebellum/neocerebellum (inputs) | From motor and sensory cortex via contralateral pontine nuclei (through MCP). |
| Cerebrocerebellum/neocerebellum (outputs) | The dentate nucleus projects to the red nucleus and VL via SCP |
| Localisation of the cerebellum | Spatial strength seems to be on the left which language seems to be on the right, this is representative of the organisation of the cortex |
| Localisation - Motor and sensory functions | Localised to the anterior lobe, with a little in one of the posterior lobe's lobules. |
| Localisation - 'higher' cognitive and emotional functions | Are strongly lateralised and are restricted to the posterior lobe |
| Localisation - Posterior vermis and Paravermis | have connections with limbic areas and lesions cause emotional liability or loss of emotional response. |
Created by:
jecca168
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