Cerebellum

Cerebellum

• little brain

• regulator of postural and coordinated movements

• guides postures and ongoing eye, head, body, limb movements

• plays a role in learning motor skills

Tentorium

• separates the occipital lobe and the cerebellum

Vermis

• separates the two lateral lobes of the cerebellum

Folia

• internal surface folds of the cerebellum

cerebellar cortex

• outer gray matter

cerebellar white matter

• underlying white matter of the cerebellum

cerebellar nuclei

• located above the fourth ventricle

• also known as the roof nuclei

anterior lobe

• located on the superior surface of the cerebellum

Posterior lobe

• largest part of the cerebellum

• located between the primary fissure and the uvulonodular fissure

Primary fissure

• separates the anterior lobe and the posterior lobe

Flocculondular lobe

• contains the flocculus and the nodule

Uvulonodular fissure

• separates the middle and flocculonodular lobe

Paleocerebellum

• controls propulsive stereotyped movements

Neocerebellum

• responsible for coordination of movements

Archicerebellum

• maintains equilibrium

• connected to the vestibular sysrem

Spinocerebellum

• associated with the interposed nuclei

Cerebrocerebellum

• associated with the dentate nuclei

Vestibulocerebellum

• associated with the fastigial nuclei

Spinocerebellum

• regulation of posture and muscle tone

• controls movement of propulsive and stereotypicsl movements

• adjustment of movement without stopping or initiating new movement

• comparator between intended and actual movement

• contains interposed nuclei

Cerebrocerebellum

• largest division

• planning and modulating movements and motor learning

• controls movement of the distal extremities

• includes speech

• contains dentate nuclei

• motor learning of intended movements

  • timing, activation of muscles, sequence, force, rate, direction, ROM

Vestibulocerebellum

• Contains the flocculus and nodulus

• Controls balance and posture

• Control of anti-gravity musculature

  • Maintaining posture against gravity

• Ocular control and eye-hand coordination (i.e. while playing video games, players must track the screen while controlling the game with their hands)

• Contains the fastigial nuclei

Vermal Zone

• Dicided into 10 lobules

• Motor coordination, muscle tone of he neck shoulder thorax abdomen and hips

Vermal lesion

• Truncal ataxia (“Drunken Sailor Gait”)

  • Walking with uncertain start and stops

  • Unequal steps

Paravermal/Intermediate Zone

• motor coordination and muscle tone of the distal limbs, especially hands and feet

Lateral Zone

• Ipsilateral motor control and muscle tone

• planning of sequential movement of the entire body

• involved in conscious assessment of movement errors

Lateral Zone

• Lesion: Limb ataxia

  • Affects fine gross motor skills

  • Clumsiness in the distal upper extremities.  (e.g. writing, buttoning clothes)

  • Finger to nose test

  • Incoordination and hand tremor

  • Need to slow down in order to figure out movements

Vertebrobasilar Artery

• Origin of all following branches

Superior Cerebral Artery

• Superior surface of the cerebellum

Anterior inferior cerebellar artery (AICA)

• Anterior and inferior parts of the cerebellum

Posterior inferior cerebellar artery (PICA)

• Interior surface of the vermis

• Central nuclei of the cerebellum

• Undersurface of the cerebellar hemisphere

Molecular Layer

• outermost layer

  • Basket cells and Stellate cells

  • Dendrites of the Purkinje and Golgi Cells

  • Axons of the granule cells

Basket cells

• receinve input from excitatory fibers

Granule Cells

• bifurcate at molecular level

• only excitatory cell in cerebellum

Purkinje layer

• middle layer

• cell bodies of the purkinje cells

Purkinje Cells

• Flask-shaped

• Arranged in a single layer

• Collateral branches of its axon make synaptic contacts with the dendrites of basket and stellate cells of the granular layer in the same area

Granular Layer

• innermost layer

  • granule cells'

  • golgi cells

  • glomeruli

Cerebellar Nuclei

• Represent the efferent pathways from the cerebellum

• Receives direct excitatory input from the pontine nuclei, inferior olivary nucleus, reticular formations, locus coeruleus, and raphe nuclei

• All are inhibited by the Purkinje cells

• All embedded within white matter

Dentate Nucleus

• Largest, most lateral

• Has an opening facing medially

• Anterior filled with white matter

• Function: involve in motor planning and execution, particularly of distal extremities

Emboliform Nucleus

• Ovoid

• Medial to dentate nucleus

• Function: Along with globose nucleus, involved in the adjustment of limb (propulsive) movements and muscle tone

Globose Nucleus

• Consists of one or more rounded cell groups 

• medial to the emboliform nucleus

Fastigial Nucleus

• Near the midline of the vermis

• Close to the roof of the fourth ventricle

• Larger than globose nucleus

• Function: Regulates posture, balance, and eye movements, mainly involving the trunk and proximal muscles.

Afferent Cerebellar Fiber System

• From the brainstem to the cerebellum

• Excitatory in nature via the glutamate or aspartate

Climbing Fibers

• Originate from the inferior olivary nucleus

• Forms synapses with Purkinje cells at molecular layer

• Moves from granule layer to molecular layer

• Utilizes glutamate or aspartate

Mossy Fibers

• Clumps-like at the granular layer

• Originate from the pontine nuclei, spinal cord, vestibular nuclei, trigeminal nuclei, formation nuclei

• Synapses with granule cells

• Utilizes glutamate only

Vestibulocerebellum Fiber System

• Fastigial nuclei → Brainstem motor nuclei

• Balance and gait

Spinocerebellum Fiber System

• Interposed nuclei → Brainstem nuclei, limb areas of the motor cortex via the thalamus

• Comparator function - intended vs actual motor output

Neocerebellum Fiber System

• Dentate nuclei → Superior peduncle → Thalamus →Areas 4 and 6

• Motor planning and coordination

Superior Cerebellar Peduncle

• “Brachium Conjunctivum”

• Attached to the midbrain

• Consists primarily of the efferent projections from the cerebellum (dentothalamic pathway)

• Dentate and interposed nuclei → rubral, thalamic, reticular areas

• Contains afferent and ventral spinocerebellar functions and some fastigiobulbar tracts

Middle Cerebellar Peduncle

• “Brachium Pontis”

• Attached to the pons

• Consists almost entirely of crossed afferent fibers from the contralateral pontine nuclei (pontocerebellar fibers)

• Projects mixed afferent and efferent fibers

Inferior Cerebellar Peduncle

• “Restiform Body”

• Attached to the medulla oblongata

• Afferent Fibers:

  • Vestibular nerve and nuclei

  • Olivocerebellar tract

  • Dorsal spinocerebellar tract

  • Some of the ventral spinocerebellar tract

  • Cuneocerebellar tract

  • Reticulocerebellar tract

• Efferent Fibers:

  • Fastigiobulbar tract

Vermal lesion

• Truncal

• LE Symptoms

Lateral Hemisphere Lesion

• UE Symptoms

Superior Cerebellar Peduncle And Deep Nuclei Lesion

• Most Severe