COORDINATIONAdelina Yasmar AlfaBag/SMF Ilmu Panyakit SarafFK-Unpad / RS-Hasan SadikinBandung 2001

Cerebellum as center of coordination-Anatomy-Physiology-Its disorder

AnatomyOccupies most of the posterior cranial fossaDorsal to the brainstem and attached to it by cerebellar peduncles :Superior cerebellar peduncle (Brachium conjunctivum) midbrainMiddle cerebellar peduncle (Brachium pontis) ponsInferior cerebellar peduncle (restiform body) medulla oblongataOther relationship : The fourth ventricleTentorium cerebelli

Anatomy (ctnd)CompositionCerebellar hemispheresVermis : cortex and medulla (incl. Nuclei)LobesAnterior lobe (palaocerebellum)C/o most of the vermis and anterior aspect of hemispheresAssociated with proprioceptive (spinecerebellar) and exteroceptive inputSignificant role in regulation of muscle tone (maintain posture)Posterior lobe (neocerebellum)The largest part; c/o main bulk of hemisphere and part of vermisReceive connections of cerebrum through nuclei & brachium pontisRole in muscular coordiantion of phasic movementFlocculonodular lobe (archicerebellum)C/o paired flocculi of hemispheres and unpaired nodulusCerebellar portion of vestibular system (somatic afferent collumn)Significant role in muscle tone, equilibrium, and posture (trunk muscles)

Anatomy (ctnd)Cerebellar cortex Layers Molecular layer :Outer layer synaptic integrative layerInput from granular layer and deep cerebellar nucleiC/o nerve fibers and some basket cellPurkinje cell layerMiddle cell layer Output layer to the intrinsic cerebellar nucleiGranular layerInnermost layer receive input from outsideCell and Nerve types

Anatomy (ctnd)Cerebellar cortex (ctnd)Cell and Nerve typesGranule cells, Purkinje cells, Basket cells, Golgi cellsMossy fibersPrimary cerebellar input from pontine nuclei and spinocerebellar pathwaysFunction : to excite the granule cellClimbing fibers (Cf)Its cell bodies located in the inferior olivary nucleusSynapse with primary and secondary dendritic branches of Purkinje cells at many sites each action potential in Cf cause a giant EPSP a burst of repetitive Purkinje cell firing

Anatomy (ctnd)Subcortical cerebellar nucleiDentate nucleiEmboliform nuclei*Globose nucleiFastigial nuclei*Relationship of cerebellar cortex and subcortical nucleiLateral areas of cortex to dentate nucleiParamedian areas to emboliform and globose nucleiMedian area (vermis) to globose and fastigial nuclei* The emboliform and globose nuclei are collectively called the nucleus interpositus

Anatomy (ctnd)Cerebellar connectionsAll fibers carrying information to and from cerebellum do so by way of the cerebellar pedunclesIncoming (afferent) fibersSuperior cerebellar peduncle : anterior spinocerebellar tract (paleo-), tectocerebellar tract (midbrain tectum to neocerebellum), trigeminocerebellar tractMedial cerebellar peduncle (entirely afferent!!) : corticopontocerebellar tract !! Each cerebellar hemisphere monitors the activity of the opposite cerebral hemisphereInferior cerebellar peduncle : conveys unconscious exteroceptive and proprioceptive fibers from the spinal cord and vestibular system :Dosrsal spinocerebellar (to paleo-)Vestibulocerebellar (to archi- of the same and opposte sides)

Anatomy (ctnd)Cerebellar connectionsOutgoing (efferent) fibers : No direct cerebellospinal pathways exist !!Superior cerebellar peduncle : primarily c/o the efferent fibers from dentate (-rubral, -thalamic,-reticular), emboliform and globose nuclei (the last two project to red nucleus, inferior olive, reticular formation) Medial cerebellar peduncle : No efferent fibers Inferior cerebellar peduncle :Through juxtarestiform body Fastigiobulbar tract (fastigial nuclei to vestibular and reticular nuclei

PhysiologyNormal cerebellar functionResponsible for muscle synergy (coordination) throughout the bodyCoordinates the action od muscles and times their contraction movement smoothly and accurately As a monitor of other center of the brain (not the iniator!)The modulator (regulator) of motor activities; integrated with :Vestibular system (maintain muscle tone and equilibrium)General proprioceptive and exteroceptive receptorsAuditory and visual systemBasically a somatic afferent organ !!

Cerebellar Disorder NeocerebellumDysmetria inability to stop the movement at the desired point (overshoots or stops before it is reached)Intention tremor evident during purposeful movement, but absent/diminished with rest. Titubation : rhytmic tremor iof the head, 3-4x/minute- lesion in the midline of cerebellumPostural disturbanceA/dysdiadochokinesis - inability to stop a movement and follow it immediately by directly opposite actionHypotonia ipsilateral to the lesion site; loss of cerebellar facilitation to the stretch reflexEye disturbance : skew deviation and nystagmus (also occurred in vestibular lesion and its connections)Disturbance of articulation and phonation : scanning speech/stacattoGait disturbance : cerebellar ataxia (tend to fall to the lesion site)

Cerebellar Disorder PaleocerebellumSymptoms and signs of postural and muscle tone disrturbanceArchicerebellumTruncal ataxia (swaying while sitting)Vertigo

Examination of coordination Equilibratory coordination - maintanance of balance and the coordination of the body as a whole; examination of station and gaitTruncal ataxia, titubationRomberg sign, Walk tandemNon-equilibratory coordination ability to carry out discrete, relatively fine, intentional movement with extremities.Dysmetria, DysdiadochokinesiaNose-to-finger test, finger-to-finger test, heel-to-knee-to-toe testRebound test, test pointing and past pointingFunctional test : button-unbuttoning, writing, picking coin at desk