Cerebellum Flashcards
location of cerebellum
- posterior cranial fossa
- posterior to 4th ventricle, pons, medulla oblongata
3 lobes of cerebellum
anterior, middle, flocculonodular lobe
- seen on the superior surface
- separated from middle lobe
anterior lobe
V shaped fissure
primary fissure
- posterior lobe
- largest part
- between primary & uvulonodar fissure
middle lobe
posterior to uvulonodar fissure
flocculonodular lobe
functional division
spinocerebellum
cerebrocerebellum
vestibulocerebellum
- receive major spinal cord inputs
- feed forward control
- control both muscle tone & execution of movements
spinocerebellum
- planning movements & motor learning
- largest
- sends outputs to thalamus & red nucleus
cerebrocerebellum
receives major inputs from vestibular system
vestibulocerebellum
cerebellar peduncles
superior, middle, inferior cerebellar peduncle
- paired structure of white matter
- connects to cerebellum to midbrain
superior cerebellar peduncle
conveys information from cerebrum & pons to cerebellum
middle cerebellar peduncle
- integrating propropceptive sensory input with motor vestibular functions
- balance & posture maintenance
inferior cerebellar peduncle
functions of cerebellum
- coordinator of precise movements
- maintain upright posture with respect to oneβs position in space
- maintain tension or firmness of muscle
- balance & equilibrium
intracerebellar nuclei
fastigal
denate
interposed nucleus
lies near the middle in the vermis & close to the roof of 4th ventricle
fastigal nucleus
- largest cerebellar nuclei
- crumpled bag with opening facing medially
- interior is made with white matter made up of efferent fibers
denate nucleus
- compromise the emboliform & glubase nucleus
- deep cerebellar complex
interposed nucleus
structures of cerebellum
white and gray matter
- resembles trunk & branches of a tree
- section made through cerebellar parallel with median plane, divides the folia at right angles
arbor vitae
gray matter
molecular, purkinje, granular layer
- contains stellate & basket cells
- neuroglial cells are found between the structures
molecular layer
scattered among dentric aborizations & numerous thin axons that run parallel to the long axis of the folia
stellate & basket cells
- large golgi type 1 neurons
- flask shaped & arranged in single layer
- integrate large amount of information & learn by remodeling their dendrites
purkinje cell layer
- packed with small cells with densely staning nuclei & scanty cytoplasm
- claw-like endings & have synaptic contact with mossy fiber input
- neuroglial cells are found
granular layer
influences movements of the long axis of the body, neck, shoulders, thorax, abdomen, hips
cortex of the vermis
control muscle of distal parts of the limbs (hands & feet)
intermediate zone of cerebellar hemisphere
- planning of sequencial movements of the entire body
- involved with conscious assessment of movement errors
lateral zone
3 groups of fibers of white matter
intrinsic
afferent
efferent fibers
- do not leave the cerebellum but connect different regions of the organ
- interconnet folia of cerebellar cortex & vermis on the same side
- connect the two cerebellar hemisphere together
intrinsic fibers
- form greater part of white matter
- enter thorugh inferior & middle cerebellar peduncle
afferent fibers
- constitute the output of cerebellum
- commence as axons of purkinje cells
efferent fibers
three masses of gray matter
intracerebellar nuclei
cerebellar cortical mechanisms
climbing & mossy fibers
origin: terminal fibers of olivocerebellar tract
climbing fibers
terminates: pass through the granular layer of cortex & terminate in the molecular layer by repeating constantly
climibing fibers
neurotransmitter: single purkinje neuron makes synaptic contact with only 1 climbing fiber; one climbing fiber makes synaptic contact to 1 to 10 purkinje neuron
climbing fibers
provide rich exitatory drive to cerebellar cortex
mossy fibers
origin: multiple brainstem nuclei (afferent tracts)
mossy fibers
terminates: granule cells in a layer below purkinje cells in cerebellar cortex
mossy fibers
neurotransmitter: immunoreactivity for inhibatory neurotransmitter GABA & GAB 67
mossy fibers
intracerebellar nuclear mechanism
climbing & mossy fiber -> purkinje cell -> deep cerebellar nuclei -> brainstem/thalamus -> brain/spinal cord
fibers going to cerebellum from cerebral cortex (afferent)
corticopontocerebellar
cerebro-olivicerebellar
cerebroreticulocerebellar
arises from nerve cells in frontal, parietal, temporal, & occipital lobe
corticopontocerebellar & cerebro-olivocerebellar
descends to corona radiata & internal capsule
corticopontocerebellar & cerebro-olivocerebellar
terminates at pontine nuclei
corticopontocerebellar
terminates at bilaterally on the inferior olivary nuclei
cerebro-olivocerebellar
arises from nerve cells from sensorimotor areas
cerebroreticulocerebellar
descends and terminates to reticular formation on the same & opposite side in pons & medulla
cerebro-olivocerebellar
- control of voluntary movement
- information of initiation of movement in cerebral cortex is transmitted to cerebellum so that movement can be monitored & appropriate adjustment in muscle activity can be made
cerebellar afferent fibers from cerebral cortex function
posterior root ganglion -> nucleus dorsalis -> c/1 anterior spinocerebellar tract and ipsi -> contralateral white column
anterior spinocerebellar tract
- convey muscle joint information from muscle spindles, tendon organs, joint receptors of upper & lower limb
- cerebellum receives information from skin & superficial fascia
anterior spinocerebellar tract
posterior root ganglion -> posterior gray column -> nucleus dorsalis -> ipsi posterior cerebellar tract and ipsi -> medulla oblongata
posterior cerebellar tract
receive muscle joint information from muscle spindles, tendon organs, joint receptors of trunk & lower limbs
posterior cerebellar tract
nucleus cuneatus
cuneo-cerebellar tract
receive muscle joint information from muscle spindles, tendon organs, joint receptors of upper limbs & upper part of thorax
cuneo-cerebellar tract
inner ear structures -> vestibular afferent fibers -> inferior cerebellar peduncle -> vestibular nuclei (other afferent)
vestibular nerve
relay sensorimotor cortex to spinal cord
red nucleus
red nucleus
red nucleus -> inferiro olivary nucleus -> contralateral anterior & posterior lobe
provide visual & auditory information
tectum
rotated & flexed
head
side of lesion is lower than normal side
shoulder
wide base & stiff legged
lower extremity
lurches & staggers toward the affected side
gait