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CEREBELLUM AND VESTIBULOCOCHLEAR NERVE

CEREBELLUM AND VESTIBULOCOCHLEAR NERVE . Prof. Sultan Ayoub Meo MBBS, M.Phil, Ph.D (Pak), M Med Ed (Dundee), FRCP (London), FRCP (Dublin), FRCP (Glasgow), FRCP (Edinburgh) Professor , Department of Physiology, College of Medicine, King Saud University, Riyadh, KSA. Table 5.3 (1) Page 144.

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CEREBELLUM AND VESTIBULOCOCHLEAR NERVE

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  1. CEREBELLUM AND VESTIBULOCOCHLEAR NERVE Prof. Sultan Ayoub Meo MBBS, M.Phil, Ph.D (Pak), M Med Ed (Dundee), FRCP (London), FRCP (Dublin), FRCP (Glasgow), FRCP (Edinburgh) Professor , Department of Physiology, College of Medicine, King Saud University, Riyadh, KSA

  2. Table 5.3 (1)Page 144 • Cerebral cortex • Cerebral cortex • Basal nuclei • (lateral to thalamus) • Basal nuclei • Thalamus • (medial) • Thalamus • Diencephalon • Hypothalamus • Hypothalamus • Cerebellum • Cerebellum • Midbrain(Mesencephalon) • Brain stem • (midbrain, pons, • and medulla) • Brain stem • Pons • Medullaoblongata • Spinal cord CEREBELLUM

  3. CEREBELLUM CEREBELLUM: Cerebellum is derived from a Latin word means "little brain.“ Cerebellum is the largest part of the hind brain, lies behind the pons and medulla Oblongata. Shape: Oval shaped, with an approximate weight is 150 gm Location: Situated in the posterior cranial fossa Anteriorly: 4th ventricle, pons, and medulla oblongata Superiorily: Covered by tentoriumcerebelli Posterio-inferiorly: Squamous occipital

  4. CEREBELLUM: THE RULE OF 3

  5. PHYSIOLOGICAL ANATOMY OF THE CEREBELLUM

  6. CEREBELLUM The cerebellum is anatomically and physiologically divided into three parts: • Paleocerebellum: Anterior lobe [Spinocerebellum] • Neocerebellum: Posterior lobe [Cerebrocerebellum] • Archicerebellum: Flocculonodularlobe [Vestibulocerebellum]

  7. CEREBELLAR PEDUNCLES: CARRY AFFERENTS FROM WHERE? Inputs to the Cerebellum from the cerebrum SuperiorCerebellar Peduncle Middle Cerebellar Peduncle Inputs to the Cerebellum from from the Pons Inferior Cerebellar Peduncle Inputs to the Cerebellum from the Medulla Oblongata

  8. CEREBELLAR PEDUNCLES: CARRY AFFERENTS FROM WHERE?

  9. CerebellarPeduncles CEREBELLAR PEDUNCLES: CARRY AFFERENTS FROM WHERE? Three paired fiber tracts connect the cerebellum to the brainstem: • Superior peduncles connect the cerebellum to the cerebrum • Middle peduncles connect the cerebellum to the pons • Inferior peduncles connect the cerebellum to the medulla

  10. TYPES OF THE CELLS INTHE CEREBELLUM

  11. CEREBELLUM LAYERS The cerebellum has an external cerebellar cortex separated by white matter from the deep cerebellar nuclei as follows: Cerebellar Cortex Molecular Layer Purkinje Cell Layer Granular Layer Cerebellar Nuclei Dentate Nucleus Globose Nucleus Emboliform Nucleus Fastigial Nuclei Note: [Globose and Emboliform also known as interpositus nucleus Purkinje cells Basket cells Golgi cells GABA…Inhabi Granular cells  Glutamate…Exci Stellate cells: Taurine…..Inhabi

  12. NUCLEI OF THE CEREBELLUM DEEP NUCLEI 1. Fastigial nucleus 2. Globose nucleus 3. Emboliform nucleus 4. Dentate nucleus

  13. OUTPUT FROM DEEP CEREBELLAR NUCLEI Fastigii Nucleus Interpositus Nucleus Dentate Nucleus Red Nucleus Premotor cortex Red Nucleus Motor Cortex Reticular Formation Control distal muscle during movement Planning of movement Its timing and initiation Control Axial muscle during movement

  14. PRINCIPAL AFFERENT TRACTS TO THE CEREBELLUM

  15. PRINCIPAL AFFERENT TRACTS TO THE CEREBELLUM

  16. PRINCIPAL EFFERENT TRACTS TO THE CEREBELLUM

  17. VESTIBULO COCHLEAR NERVE The vestibulo cochlear nerve conducts hearing (audition) and balance (vestibular). The receptor cells are located in the membranous labyrinth which is embedded in the petrous part of the temporal bone. There are two specialized organs in the bony labyrinth, the cochlea and the vestibular apparatus. The vestibular apparatus senses head position changes relative to gravity. Movement causes fluid vibration resulting in hair cell displacement that activates the vestibular part of the eighth nerve.

  18. VESTIBULOCOCHLEAR NERVE

  19. VESTIBULOCOCHLEAR NERVE

  20. VESTIBULOCOCHLEAR NERVE

  21. CEREBELLUM AND VOLUNTARY MOTOR CONTROL Cerebral and cerebellar control of voluntary movements, involving especially the intermediate zone of the cerebellum.

  22. CONNECTIONS OF THE CEREBELLUM

  23. MAIN CONNECTIONS OF THE PALEOCEREBELLUM RED NUCLEUS NUCLEUS INTERPOSITUS Rubro spinal tract Inferior Olivry nucleus ANTERIOR LOBE PARAVERMAL ZONE Lower motor neuron PALEOCEREBELLUM SPINAL CORD Spinocerebellar tract

  24. MAIN CONNECTIONS OF THE NEOCEREBELLUM CEREBRAL CORTEX THALAMUS DENTATE NUCLEUS pyramidal tract Pontine Nucleus POSTERIOR LOBE CEREBELLAR HEMISPHERE lower motor neuron NEOCEREBELLUM LMN

  25. MAIN CONNECTIONS OF THE VESTBULOCEREBELLUM Vestibular Organ Floculonodular Lobe Vermis VESTIBULAR NUCLEUS vestibulospinal tract FASTIGIAL NUCLEUS MLF lower motor neuron ARCHICEREBELLUM LMN

  26. CEREBELLUM AND AUTOMATIC MOTOR CONTROL CEREBELLUM Motor Cortex Red Nucleus Vestibular Nucleus Reticular Formation Lower Motor Neuron (LMN) Proprioceptors

  27. Vestibulocerebellum • Spinocerebellum • Cerebrocerebelum CEREBELLUM Anterior Lobe Primary fissure It makes the movements smooth and coordinated Posterior Lobe It interacts with motor cortex in planning & programming of movements. Flocculo-Nodular Lobe (FN lobe) Maintenance of balance, control of eye movements • Folia

  28. FUNCTIONAL DIVISION OF THE CEREBELLUM

  29. SUMMARY: FUNCTIONS OF CEREBELLUM

  30. CEREBELLAR LESION

  31. CLINICAL FEATURES / TESTS RELATED TO CEREBELLUM

  32. FINGER NOSE TEST While the examiner holds his finger at arm's length from the patient. Patient touches her nose and then touches the examiner's finger. After several sequences, the patient is asked to repeat the exercise with her closed eyes. A patient with a cerebellar disorder tends to miss the target.

  33. FINGER NOSE TEST

  34. FINGER NOSE TEST

  35. DYSDIADOCHOKINESIS: RAPIDLY ALTERNATING MOVEMENTS Dysdiadochokinesis: Inability to perform rapidly alternating movements. Is called dysdiadochokinesia. It is usually caused by multiple sclerosis in adults and cerebellar tumors in children. Patients with other movement disorders (e.g. Parkinson's disease) may have abnormal rapid alternating movement testing secondary to akinesia or rigidity, thus creating a false impression of dysdiadochokinesia.

  36. DYSDIADOCHOKINESIS: RAPIDLY ALTERNATING MOVEMENTS

  37. HEEL TO SHIN TEST The heel to shin test is a measure of coordination and may be abnormal if there is loss of motor strength, proprioception or a cerebellar lesion. If motor and sensory systems are intact, an abnormal, asymmetric heel to shin test is highly suggestive of an ipsilateralcerebellar lesion.

  38. CEREBELLAR SIGNS Response delays Hypometria & Ataxia Incoordination/ rapid alternatingmovements (disdiadochokinesia)

  39. THANK YOU

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