Cerebellum - Lec11 Flashcards
What are the basic function of the cerebellum?
Major role in timing of motor activities and in rapid, smooth progression from one muscle movement to the next:
- not essential for locomotion
- helps sequence motor activities
- moniters and makes corrective adjustments to motor activities while being exectutes
- actual movement vs intended movements
- kinesthetic memory
- enhances stretch relfex
- work with braistem for postural movements
- turns on antagonist at proper time
- programing of contraction
What are the 3 lobes of the cerebellum?
Anterior lobe
posterior lobe
Flocculonodular lobe - vestibular system
Which lobe of the cerebellum is evolutionary the oldest?
Flocculonodular lobe
What are the folia?
The gyri of the cerebullum because they look like pages of a book
What and where is the vermis? What is the function?
.vermis seperates the left and right hemishperes of the the cerebellum
Each hemisphere is divided into an intermediate zone and lateral zone
Function: control of muscle movements of the axial body, neck, shoulders and hips
(Posture)
What are the general functions of the intermediate and lateral zones?
Intermediate: contraction in the distal portions of the upper and lower limbs
-hands, feet, fingers, toes
Lateral zone: association with the cerebral cortex and plannign of sequential motor movements
What are the four pairs of deep cerebellar nuclei and what do lesion do to normal funciton?
Dentate Emboliform Globose -> lesions: extremeity ataxia ((all three above) Fastigial -> lesions: trunk ataxia
What cells make upp the cerebullar cortex and their circuitry?
Granular layer
-granule cells, gogle type II cells and glomeruli
Purkinje cell layer
-purkinje cells
Molecular layer
-stellate cells, basket cells, purkinje dendrites, golgi type II cells and axons of granule cells
Functional unit of the cerebellum
A single purkinje cells and a deep nuclear cell it projects too
Output is form a deep nuclear cell
Inputs also from climbing and mossy fibers
What are pendular movements? How does the cerebellum effect pendular movements? /
Swinging back and forth
Cerebellum is good for stopping the body at the intended time (dampening) without the movemnts would overshoot
What are ballistic movements?
movements that are so rapid they it’s not possible to receive feedback from cerebellum meaning they have to be preplanned
What does the removal of the cerebellum do to movements of the body?
.causes movements to be slow to develop
Force develop is weak
Movements are slow to turn off
Granular cells
Axons forms parallel fibers in cortex (+)
Golgi cells
Project from parallel fibers to granular cell bodies (-)
Basket cells
Project parallel fibers to purkinje axon hillock (-)
Stellate cells
From parallel fibers to purkinje dendrites (-)
What two cells provide laterall inhibition on purkinje cells?
Basket and stellate cells
Vestibulocerebellum
Flocculonodular lobes and vermis
Control of balance and eye movemtns
Fibers incoming from vestibular system and oculomotor system
Output to vestibular system
Related to pendular movments
Spinocerebellum
Vermis and intermediate zone
Synergic function: control of rate, force, range and direction of movemnt
Recieves: info from motor cortex and red nucleus about intended body movement plan
-feedback of what the actual movements are
Sends correctections to motor cortex through thalamus and magnocellular portion of red nucleus
Cerebrocerebellum
Lateral parts of hemishperes
Associated with premotor, primary and association areas of the cerebral cortex
Recivees corticopontocerebellar projections
Coordination of skilled movement and speech
Plans a 1/10th of a second in advanced
Afferent Tracts to cerebellum
Corticopontoocerebellar Vestibulocerebellar Reticulocerebellar Spinocerebellar (ventral and dorsal) Olivocerebellar
Dorsal spinocerebellar
From muscle spindles to ipilaterally in vermis andi ntermediate zones
- muscle contractions
- degree of tensio non the muscle spindles
- positions and rates of movements of parts of the body
- forces acting on surfaces of the body
Kinesthetic informaitaon
Ventral spinocerebellar
terminates ipsilaterally and contralaterally
Signals from cortex through the corticospinal and rubrospinal tracts and internal motor pattern generators within the spinal cord
Gives cerebellum (is part of the cerebellum) information about which motor signals arrive at the anterior horns
Olivecerebellar
Forms climbing fibers
Prom inferior olivary nuclei in medulle to purkinje cell dendrites (+) and to intracerebellar nuclei
Causes a prolonged AP on purkinje cells, one climbing fiber connects to 5-10 purkinje cells.
Afferent tracts that form the ‘mossy’
Corticopontocebellar
Vestibulocerebellar
Reticulecerebellar
Spinocerebellar
Mossy fibers terminate on granule cells in the cerebellar cortex - excitory
Which of the afferent tracts are the climbing fibers?
olivocerebellar
Name the efferent tracts
Cerebelloreticular
Cerebelothalamocortical
Cerebellorubral
Cerebellovestibular
Dysmetria and Ataxa
Symptoms of cerebellar disease
Brain cant tell how far away an object is and ofter overshoots movements and overcompensates- dysmetria- the difference resulting in uncoordinated movement -ataxia-
Past pointing
Absence of cerebellum
Overreaching - difficulty in stopping a movement
Dysdiadochokinesia
Inability to perform rapidly alterating movements
Dysarthria
Inability to oordinate muscles to form words
Cerebellar nystagmus
Flickering eye movements
Eye tremor, eye fixed off toward side
Hypotonia
Reduced or loss of muscle tone
