• Cerebellum is Covered superiorly by

• Location of Cerebellum

CEREBELLUM forms the roof of the

(a)  

Deepest fissure

(a)  

• Separates anterior and middle (posterior) lobe

• Posterolateral fissure

• Ventroinferior surface

• Separates the middle lobe from flocculonodular lobe

• Along the margin of the cerebellum separates the superior from the inferior surfaces

• Superior surface and separated from middle (posterior) lobe by the primary fissure

• Largest,

• Between the primary and uvulonodular fissure

• Herniate through the foramen magnum in cases of increased intracranial pressure

• Death via compression of medullary respiratory centers

• Influences movement of the long axis of the body (neck, shoulder, thorax, abdomen and hips)

• Balance and vestibulo-ocular reflex

• Cerebellar Hemispheres

• Immediately lateral to the vermis

• Control muscles of distal parts of limbs

• Planning of sequential movements of entire body

• Conscious assessment of movement errors

• Small ridges that run from medial to lateral surface of the cerebellum (leaves)

• OUTER cells of MOLECULAR Layer

• INNER cells of MOLECULAR Layer

• unmyelinated granule cell axons

• Scattered among dendritic arborizations & numerous thin axons that run parallel to long axis of folia granule cell axons

• Contains: Purkinje cells

• What type of neuron is the Purkinje cells

• Shape of the Purkinje cells

• Arranged in a single layer

• Primary and secondary branches are smooth and subsequent branches are covered by short, thick dendritic spines

• Spines form synapses w/ parallel fibers from granule cell axons

• Purkinje axons pass through the (a)   layer to enter the white matter

• (a)   branches of Purkinje fibers synapses w/ dendrites of basket and stellate cells of the molecular layer in same area or in distant folia

• Where do Purkinje Fibers terminate

• Few Purkinje axons pass directly to (a)  

• Contains Granular cells

• Small cells with densely staining nuclei and scanty cytoplasm

• Each cells gives rise to 4-5 dendrites which synapses w/ mossy fiber input

• Axons pass through molecular layer and bifurcates at a T junction

• dendrites ramify in molecular layer and axons terminate with dendrites of granular cells

• Composed of large, multipolar neurons w/ branching dendrites

• Axons form the cerebellar outflow in the superior and inferior cerebellar peduncles

• Receive collateral fibers of cerebellar inputs on their way to the cerebellar cortex

• All outputs from cerebellum are relayed by

• Largest Nucleus

• Crumpled bag w/ opening facing medially

• Active just before voluntary movement

• Interior is filled w/ white matter - efferents that leave the nucleus to form superior cerebellar hemisphere

• Ovoid Nucleus

• Medial to the dentate

• Consist of one or more rounded cell groups medial to the emboliform nucleus

• Emboliform and Globose

• Receive input from intermediate part of cerebellar hemisphere

• Active during and in relation to movement

• Region of Dentate Nuclei

• Region of Interposed Nuclei

• Region of Fastigial Nuclei

• Region of Vestibular Nuclei

• closely resembles trunk and “branches of a tree”

• do not leave cerebellum, connects different regions within the organ ie vermis and cerebellar cortex

•  greater part; proceed to cerebellar cortex; enter through inferior and middle cerebellar peduncle

Output

(a)  

• Start as axons of Purkinje cells of the cerebellar cortex, synapse with neurons of the cerebellar nuclei then leave the cerebellum

• as Purkinje axons in flocculonodular and leave w/out synapsing

• carry mainly output from cerebellum

Output from cerebellum decussates at the level of

(a)  

• carry mainly input

Climbing Fibers are terminal fibers of

(a)  

Exclusively from contralateral inferior olivary nucleus

(a)  

• Pass through granular layer and terminate in the molecular layer by branching

• Each climbing fiber synapses profusely with dendrites of Purkinje cell (wrap around the cell body and proximal dendritic tree of the purkinje cells) forming excitatory synapses

1 climbing fibers : (a)    Purkinje cells

1 Purkinje cells : 1

(a)  

Few branches synapse with stellate and basket cells

(a)  

• Arise from numerous regions

• Terminal fibers of all other cerebellar afferent tracts

• Ascend in cerebellar white matter to form excitatory synapses onto dendrites of granule cells

• (a)   send axons to molecular layer, which bifurcate, forming parallel fibers that run parallel to the folia

• Each parallel fiber forms excitatory synapse with numerous (a)   cells

• 1 mossy fiber: thousand of (a)   cells through granule cells 

• All cerebellar cortex outputs are carried by (a)   cell axons into the cerebellar white matter

• (a)   cells form inhibitory synapses on to the deep cerebellar nuclei and vestibular nuclei, which then convey outputs to other 

regions through excitatory synapses

• All cerebellar cortex outputs are carried by (a)   cell axons into the cerebellar white matter

• Stellate cells terminate on

• Basket cells on

• Receive excitatory inputs from the granule cell parallel fibers in the molecular layer then provide feedback inhibition onto the granule cell dendrites

• Shorten the duration of excitatory inputs to the granule cell

Excitatory Neurotransmitters

(a)  

• Climbing and mossy fibers to dendrites of Purkinje cells

• Possibly to modify the action of glutamate on Purkinje cells

• mossy fibers and climbing fibers

• Least well characterized of these pathways

• Appears to be the upper-extremity equivalent of the ventral spinocerebellar tract, and it enters the cerebellum through both the inferior and superior cerebellar peduncles 

• Convey information concerning the position of the head and body in space

• As well as information useful in orienting the eyes during movement

•  outputs from the basal ganglia terminate

• output from cerebellum terminate in

Dentate nucleus affect motor activity via

(a)  

Impulses from motor cortex are transmitted to spinal segmental levels through

(a)  

Blood Supply to the Cerebellum