The Cerebellum, Balance and Coordination Flashcards
What connects the cerebellum to the medulla? And what is the function of this pathway?
- Inferior peduncles connect cerebellum to medulla – sensory information from muscle proprioceptors

What connects the cerebellum to the pons? And what is the action of this pathway?
- Middle peduncles connect cerebellum to pons – voluntary motor activities by motor cortex

What connects the cerebellum to the midbrain? And what is the action of this pathway?
- Superior peduncles connect cerebellum to midbrain – neurons in deep cerebellar nuclei and communication with motor cortex via thalamus

What is the cerebellar output?
occurs via deep nuclei - tonically activated by climbing and mossy fibres
From lateral to medial:
- Dentate nucleus
- Emboliform nucleus
- Globose nucleus
- Fastigial nucleus
**Emboliform + globose nucleus = interposed

What is the action of climbing and mossy fibres in the cerebellum?
integrate sensory information (excitatory)
What is the action of the golgi and purkinje cells of the cerebellum?
inhibitory output
Describe the function of the cerebellum
Stimulation of the cerebellum causes neither sensation nor significant movement. However, loss of cerebellum leads to severe abnormalities of motor function
Describe the function of the cerebellum as a comparator
- Cerebellum compares descending supraspinal motor signals with ascending afferent feedback information
- Movement smoothly and accurately coordinated
Describe the function of the cerebellum as a timing device
- Pontocerebellum – creates a sequence for motor activation
- Vestibulocerebellum – maintains balance
- Spinocerebellum – maintains posture
Describe the action of the cerebellum in initiating and storing movements
- Modifiable synapse (Purkinje cell)
- So can store motor information and update it
Give an overview of the motor regulatory function of the cerebellum
- Modulates motor output based on integration of:
- Activity in the pre-motor & motor areas as well as spinal motor circuits (information about potential motor output)
- Sensory feedback from vestibular system, visual system, and ascending proprioceptive information (about real motor input)
- Modulation by the cerebellum is affected at the motor cortex and brainstem
What is thought to be the primary role of the cerebellum?
- Primary role of cerebellum thought to be a supplement and correlate activities of other motor areas e.g. correction of rapid muscular movement initiated by cortex (typing, musical instrument)

What is the action of the cerebellum due to inputs from muscle spindles and golgi tendon organs
- Secondary role in control of postural mechanisms
- Exerts control on a moment-by-moment basis
- Third role in maintenance of tone of muscles
- Cerebellum informed of movement by cortex before it occurs, then cerebellum processes sensory information to generate an error signal which is fed back to cortex and movement Is adjusted

What are the main clinical features of cerebellar damage?
- Hypotonia/Reduced muscle tone
- Incoordination/Ataxia
- Dysarthria (scanning speech)
- Nystagmus
- Palatal Tremor/Myoclonus
Why does hypotonia/reduced muscle tone occur in cerebellar damage?
- Due to reduced input from Deep Cerebellar Nuclei neurone (DCNN) via descending motor pathways to muscle spindle
Asynergy
- inability to coordinate contraction of agonist and antagonist muscles
Dysmetria
inability to terminate movements (intention tremor/past pointing)
Dysdiadochokinesis
- inability to perform rapidly alternating movements
Dysarthria
- Inability to articulate words (slurred and delivered slowly) due to inco-ordinated oropharyngeal musculature
Nystagmus
- Rapid jerky eye movements – disruption between vestibular nucleus and oculomotor nuclei
Palatal tremor/Myoclonus
- Rare condition
- Hypertrophy of inferior olive which causes damage to dentate nucleus of cerebellum and red nucleus in midbrain
Describe the inputs and outputs that control balance and co-ordination
- Inputs
- eye
- joint position, proprioception, superifical sensation
- Labyrinthine activity
- cortex cerebellum, reticular formation, extra-pyramidal system
- Outputs
- cortical awareness of head/body/motion
- Eye movement/control of oculomotor activity
- control of posture
- control of motor skills

What is the function of the auditory system and the vestibular apparatus?
- Auditory system provides sense of hearing
- Vestibular generates out sense of balance
What is the function of different aspects of the ear?
- Pinna collects and focuses sound waves
- External auditory canal, also skin lined ends up at tympanic membrane (eardrum)
- Middle ear is air filled chamber, bounded by tympanic membrane on one side and oval window on the other
- Eustachian tube connects middle ear to nasopharynx, allows pressure equalisation










