The cerebellum is located under the occipital lobe and consists of cerebellar cortex and deep cerebellar nuclei. It can be divided into three lobes - the anterior lobe, posterior lobe, and flocculonodular lobe. The cerebellum receives proprioceptive and exteroceptive sensory input and coordinates voluntary movement through outputs to motor areas of the cortex and brainstem. Damage to the cerebellum results in ataxia and impaired motor coordination.

4. Anatomy of the Cerebellum 2 symmetrical hemispheres connected medially by the Vermis Folia: Transversely oriented gyri 3 lobes in each hemisphere: Anterior, Posterior, Flocculonodular (FN) Neural arrangement: Gray matter (Cortex), White matter (Internal), Scattered cerebellar nuclei: dentate, globose, emboliform, fastigial Arbor vitae (tree of life): distinctive treelike pattern of the white matter Folium

5. Divisions of the Cerebellum nodulus flocculus Ant Lobe Ant Lobe Post Lobe Post Lobe tonsil Ventral View Superior Surface vermis hemisphere Ant Lobe Post Lobe nodulus flocculus Schematic

6. Cerebellum Regulation of muscle tone, coordination of skilled voluntary movement Planning of voluntary activity Maintenance of balance, control of eye movements Anterior Lobe Posterior Lobe Flocculo-Nodular Lobe (FN lobe) Folia Primary fissure Vestibulocerebellum Spinocerebellum Cerebrocerebelum

8. Cerebellar Peduncles Medulla Inferior (ICP) Pons Middle (MCP) Midbrain Superior (SCP) Connects to Peduncle SCP SCP SCP MCP MCP MCP ICP ICP ICP

21. Simplified Cerebellar Circuitry Spinal Cord, Cerebral Cortex (via pontine nuclei), Vestibular System Cerebellar Cortex Inferior Olive Deep Cerebellar Nuclei Brainstem, thalamus, midbrain Mossy Fibers Climbing Fibers Spinal cord, Cerebral Cortex + - + INPUT

22. Microscopic Sections Cortex Mol Gr WM Purkinje Molecular Granular Inner Middle Outer Granular layer Purkinje cell layer Molecular layer Granule cells, Golgi cells Purkinje cells Stellate cells, Basket cells

24. 5 cell types Stellate (inhibitory) Basket (inhibitory) (molecular layer) Purkinje (inhibitory) (Purkinje layer) Golgi (inhibitory) Granule (excitatory) (Granular layer) Microcircuitry of cerebellum

27. Purkinje Cell Recieves + inputs from parallel fibers and climbing fibers Recieves - inputs from basket cells, Golgi cells, stellate cells Heavily invested with glial processes

33. Cerebellar Peduncles Superior peduncles (to the midbrain): Fibers originate from neurons in the deep cerebellar nuclei & communicates with the motor cortex via the midbrain and the diencephalon (thalamus) Middle peduncles (to the pons): Cerebellum receives information advising it of voluntary motor activities initiated by motor cortex Inferior peduncles (to the medulla): Afferents conveying sensory information from muscle proprioceptors throughout the body & from the vestibular nuclei of the brainstem (Spinal cord)

36. Afferent Connections (1): 1. Inferior Cerebellar Peduncle Restiform Body Posterior Spinocerebellar Tract Olivocerebellar tract Cuneocerebellar Tract Reticulocerebellar Tract Juxtarestiform Body Vestibulocerebellar Tract Cerebellum Connections

37. Afferent Connections (2): 2. Middle Cerebellar Peduncle Pontocerebellar fiber Fibers from raphe nuclei 3. Superior Cerebellar Peduncle Anterior Spinocerebellar Tract Tecto-cerebellar tract Trigemino-cerebellar tract Fibres from locus coeruleus Cerebellum Connections

38. Efferent Connections : 1. Superior Cerebellar Peduncle Cerebellothalamic fiber - from 3 deep nuclei to VPLo, VLc, CL Cerebellorubral fiber - from nucleus interpositus and dentate nucleus both goes to cortex Cerebello-rubro-spinal tract Fibers to reticular formation and olivary complex 2. Inferior Cerebellar Peduncle Fastigiovestibular fiber Cerebello-reticular cerebello- olivary tract Cerebellum Connections

39. Outputs of the Cerebellum Dentate nuclei: project contralaterally through the superior cerebellar peduncle to neurons in the contralateral thalamus & from thalamus to motor cortex Func.: influence planning and initiation of voluntary movement Emboliform & Globose nuclei: project mainly to the contralateral red nuclei & a small group is projected to the motor cortex Red Nuclei  Rubrospinal Tract control of proximal limb muscles Fastigial nuclei: project to the vestibular nuclei & to the pontine and medullary reticular formation Vestibulospinal & Reticulospinal tracts Cerebellar nuclei: dentate, globose, emboliform, fastigial

41. MLF Main Connections of the Vestibulocerebellum lower motor neuron LMN vestibulospinal tract FASTIGIAL NUCLEUS Vestibular Organ Floculonodular Lobe Vermis ARCHICEREBELLUM VESTIBULAR NUCLEUS

42. Main Connections of the Paleocerebellum lower motor neuron SPINAL CORD rubrospinal tract NUCLEUS INTERPOSITUS Inferior Olivry Nucleus ANTERIOR LOBE PARAVERMAL ZONE PALEOCEREBELLUM RED NUCLEUS spinocerebellar tract

43. CEREBRAL CORTEX DENTATE NUCLEUS Main Connections of the Neocerebellum lower motor neuron LMN pyramidal tract POSTERIOR LOBE CEREBELLAR HEMISPHERE THALAMUS NEOCEREBELLUM Pontine Nucleus

44. upper motor neuron UMN BASAL GANGLIA Pyramidal Tract and Associated Circuits lower motor neuron UMN pyramidal tract Cerebellum

45. Reticular Formation CEREBELLUM Cerebellum and Automatic Motor Control Lower Motor Neuron (LMN) Motor Cortex Red Nucleus Vestibular Nucleus Proprioceptors

46. Olivocerebellar Connections Caudal portion of medial and dorsal accessory olivary nucleus ----------------- vermis of cerebellar cortex (A and B) fastigial nucleus vestibular nucleus Rostral portion of medial and dorsal accessory olivary nucleus ----------------- paravermal region (C 1 , C 2 , C 3 ) nucleus interpositus Principal Inferior Olivary Nucleus ----------------- cerebellar hemisphere (D 1 , D 2 ) dentate nucleus Cerebellum Connections

47. Cerebellum Function  Maintenance of Equilibrium - balance, posture, eye movement  Coordination of half-automatic movement of walking and posture maintenance - posture, gait  Adjustment of Muscle Tone  Motor Learning – Motor Skills  Cognitive Function

60. Posture Gait – Ataxia Tremor

61. Cerebellar Ataxia Ataxic gait and position: Left cerebellar tumor a. Sways to the right in standing position b. Steady on the right leg c. Unsteady on the left leg d. ataxic gait a b c d

62. Cerebellar tumors on vermis - Truncal Ataxia - Frequent Falling The child in this picture: - would not try to stand unsupported - would not let go of the bed rail if she was stood on the floor. Cerebellar Medulloblastoma