Cerebellum Function & Disorders PDF

ProfMTPhD  The cerebellum regulates voluntary movement & posture (balance and muscle tone)- indirectly by adjusting the output of the major descending systems of the brain +motor learning Lesions of the cerebellum: disrupted coordination of eye and limb movements, impair balance and dec...

ProfMTPhD  The cerebellum regulates voluntary movement & posture (balance and muscle tone)- indirectly by adjusting the output of the major descending systems of the brain +motor learning Lesions of the cerebellum: disrupted coordination of eye and limb movements, impair balance and decrease muscle tone The cerebellum constitutes 10% of the total volume of the brain, yet it contains more than half of all the neurons Location and relationships 3. ventricle 4. ventricle Superior view (Posterior lobe) Postero-superior view Inferior view Anterior view Arbor vitae CEREBELLAR PEDUNCLES Cerebellar cortex Cerebellar medulla  CEREBELLAR NUCLEI Ant interpositus nuc. Post interpositus nuc.  Coronal section from the SCP Coronal section post to the one above Post lobe Lobes of Cerebellum  CEREBELLAR AFFERENTS From the spinal cord via the anterior, Proprioceptive posterior spinocerebellar tracts and information from upper and lower cuneocerebellar tract limbs From the vestibular apparatus (vestibulocerebellar tract) through the vestibular nuclei and a very small number of fibers as directly From the cerebral cortex (motor, premotor, sensory and posterior parietal cortex) via the corticopontocerebellar tract Tectocerebellar, rubrocerebellar, reticulocerebellar  Post spinocerebellar tract (upper extremities) >inf. cerebellar peduncle Ant spinocerebellar tract (lower extremities) >sup. cerebellar peduncle  CEREBELLAR EFFERENTS Efferents of the cerebellum begin from the deep cerebellar nuclei (a few begin from the cerebellar cortex). These nuclei in turn control different components of the descending (motor) pathways. Vestibular nuclei are considered functionally as part of the deep cerebellar nuclei. Functional divisions Efferents connect to * the vestibular nuclei, red nucleus, inf olivary nucleus, reticular nuclei, spinal cord, and thalamus * Cerebrocerebellum * balance and eye movements are related to the vestibulocerebellum (flocculonodular lobe) Efferent fibers of cerebellum to the red nucleus and thalamus Sup cerebellar peduncle: Cerebellar efferents, ant. spinocerebellar tract Middle cerebellar peduncle: Corticopontocerebellar tract Inf cerebellar peduncle: Post spinocerebellar tract, cuneocerebellar tract  Arteries of the cerebellum Posterior inferior cerebellar artery (PICA) (branch of the vertebral artery) Anterior inferior cerebellar artery (AICA) (branch of the basilar artery) Superior cerebellar artery (SCA) (branch of the basilar artery).  SCA AICA PICA Venous drainage of superior vermian vein the cerebellum >great cerebral vein of galen>straight sinus inferior vermian vein >straight sinus superior cerebellar vein >straight sinus superior &inferior cerebellar hemispheric veins >transverse sinus some veins drain into the posterior spinal vein FUNCTION & DISORDERS Control of posture and equilibrium Control of muscle tone and stretch reflex Control of voluntary movements § Ataxia (loss of control of movement) § Tremors (involuntary quivering) § Nystagmus (involuntary eye movements) § Dysarthria (speech disorder) § Astasia (inability standing upright without help) Tests: Please see- Finger-nose test (https://www.youtube.com/watch?v=TeEI2HcOOcE) Tandem gait (https://www.youtube.com/watch?v=iNOTo4tgqhE) Diodochokinesis (https://www.youtube.com/shorts/PQ4oR-SY6xA) Romberg’s test (https://www.youtube.com/shorts/xpVYU1UUkDc)