Cerebellum Flashcards
What is the function of the cerebellum?
Important motor part of the brain:
- Production of coordinated movement (speed, direction)
- Maintain equilibrium, balance and posture
- Co-ordinates appropriate time, force and duration of muscle contraction (synergy: two or more actions come together to produce an effect e.g. information from the primary motor cortex and information from the limbs)
- May store instruction for patterns of movement
- May have linguistic and cognitive functions
Does the cerebellum act ipsilaterally or contralaterally?
Cerebellum acts ipsilaterally: receives information from the same side and acts for the same side.
Which 2ary vesicle does the cerebellum develop from?
metencephalon
Where is the cerebellum located? In which cranial fossa?
- Found under the occipital lobes of the cerebral hemispheres
- In the posterior cranial fossa
How is the cerebellum separated from the occipital lobes?
By the tentorium cerebelli (tough layer of dura mater)
How is the cerebellum attached to the brainstem?
By 3 paired cerebellar peduncles
Which part of the brainstem does the cerebellum lie posterior to?
It lies at the same level of and posterior to the pons
How is the cerebellum separated from the pons?
By the 4th ventricle
The cerebellum consists of two hemispheres. What are these connected by?
Vermis; a narrow midline area
How many anatomical lobes does the cerebellum have?
3; the anterior lobe, the posterior lobe and the flocculonodular lobe.
How are the lobes of the cerebellum separated?
These lobes are divided by two fissures – the primary fissure and posterolateral fissure.
The cerebellum also has tonsils (2 small areas at the bottom). What can happen in situations of increased
Tonsils can herniate through the foramen magnum and compress the medulla.
The cerebellum can also be divided by function. How many functional areas are there? What are they?
There are three functional areas of the cerebellum:
- Cerebrocerebellum
- Spinocerebellum
- Vestibulocerebellum
What forms the vestibulocerebellum (archicerebellum)?
- Comprised of the flocculonodular lobe and part of the vermis
- Seen here in blue
What is the spinocerebellum also referred to as?
paleocerebellum
What is the vestibulocerebellum also referred to as?
archicerebellum
What is the cerebrocerebellum also referred to as?
neocerebellum
What comprises the spinocerebellum?
Comprises most of the vermis and adjacent region of hemispheres (seen here in purple)
What comprises the cerebrocerebellum?
- Comprises lateral parts of the hemispheres
- Seen here in green
The cerebellum is somatotopically organised. What does this mean?
Cerebellar homunculus: homunculus matches up to the function of specific subdivisions
Function of the vestibulocerebellum?
- Has a role in the vestibular system of the Inner ear, controlling balance
- Coordinates muscles involved in maintaining balance and constancy of visual fields
- Receives input from the vestibular apparatus of the inner ear
Function of the spinocerebellum?
- Receives connections from the spinal cord
- Co-ordinates muscles involved in posture and locomotion
Function of cerebrocerebellum?
- Receives input from the cerebrum/cortex
- Co-ordinates movements of distal limbs. Particularly fine, skilled and targeted movements of hands (also involved in learning, linguistic and cognitive functions
Which functional division of the cerebellum is only seen in higher functioning animals?
Cerebrocerebellum; region developed later on in evolution
Which functional division of the cerebellum regulates balance and eye movement?
Vestibulocerebellum
Where does the vestibulocerebellum receive info from? Is this info ipsi or contralateral?
- Receives input from the vestibular apparatus and nuclei of the inner ear
- Ipsilateral info from balance
Describe how detection of change in balance leads to muscle/eye movements (Vestibulocerebellum)
- Neurons in vestibular apparatus (inner ear) detect change in balance
- Fire action potentials using the vestibular division of the vestibulocochlear nerves
- Information reaches brainstem (vestibular nuclei in medulla)
- Information then sent to flocculus and nodulus of cerebellum
- Response: Adjusts muscles and eyes movements in response to vestibular stimuli.
Which divison of the cerebellum deals with a change in balance?
Vestibulocerebellum
Function of the vestibular apparatus?
The vestibular system is the sensory apparatus of the inner ear that helps the body maintain its postural equilibrium.
Which afferent neurons does the vestibulocerebellum receive?
Recieves vestibulocerebellar afferents from the vestibular nuclei of the same side, travelling via the inferior cerebellar peduncle
Describe the afferent and efferent pathway for the vestibulocerebellum.
Afferent:
- Vestibulocerebellar afferents receives (ipsilateral) information from the vestibular apparatus
- Information is sent via the vestibular division of the vestibulocochlear nerve to the vestibular nuclei of the brainstem
- Vestibulocerebellar afferents have their nuclei (vestibular nuclei) in the medulla
- Reach cerebellum via the inferior cerebellar peduncle (due to nuclei being in medulla)
Efferent:
- Cerebellovestibular efferent fibres leave cerebellum via inferior cerebellar peduncle
- They reach vestibular nuclei in the medulla then enter:
- Vestibulospinal tract –> LMNs to co-ordinate muscles to contract in relation to balance.
- Medial longitudinal fasciculus –> LMNs to cranial nerve nuclei (3, 4, 6) which control movements of the eyes.There will also be LMNs to the neck, to allow for head turning
What are the afferent fibres of the vestibulocerebellum called?
vestibulocerebellar afferent fibres
What are the efferent fibres of the vestibulocerebellum called?
cerebellovestibular efferents
Cerebellovestibular efferents can enter 1 of 2 tracts when responding to a change in balance. What are these 2 tracts and what is the response?
- Vestibulospinal tract –> LMNs travels via the vestibulospinal tract which will co-ordinate muscles to contract in relation to balance –> help keep you upright
- Medial longitudinal fasciculus –> LMNs to cranial nerve nuclei (3, 4, 6) which control movements of the eyes. There will also be LMNs to the neck, to allow for head turning.
Which tract connects the vestibular nuclei to the neck LMNs and cranial nerve nuclei (III, IV and VI)?
Medial longitudinal fasciculus
What are semicircular canals?
Your semicircular canals are three tiny, fluid-filled tubes in your inner ear that help you keep your balance.