Cerebellum Study Guide - College 7 PDF

Chapter 15 Opener FIGURE 15.1 Cerebellum and Posterior Fossa, Sagittal View in Situ FIGURE 15.2 Lateral View of the Cerebellum Attached to the Brainstem FIGURE 15.12 Vascular Territories of Cerebellum FIGURE 15.3 Subregions of the Cerebellum and Attachments of the Cerebellar Peduncles to the Bra...

Chapter 15 Opener FIGURE 15.1 Cerebellum and Posterior Fossa, Sagittal View in Situ FIGURE 15.2 Lateral View of the Cerebellum Attached to the Brainstem FIGURE 15.12 Vascular Territories of Cerebellum FIGURE 15.3 Subregions of the Cerebellum and Attachments of the Cerebellar Peduncles to the Brainstem (Part 1) Sensorimotor arm, leg, (motor cortex) (Lobules I-V) Receives info from posterior parietal and prefrontal Cognitive functions (Lobules VI-IX, Crus I) Social functions: (Crus II) Trunk muscles – vestibulo-ocular control FIGURE 15.3 Subregions of the Cerebellum and Attachments of the Cerebellar Peduncles to the Brainstem (Part 2) FIGURE 15.3 Subregions of the Cerebellum and Attachments of the Cerebellar Peduncles to the Brainstem (Part 3) Balance, eye movements via vestibular circuit (Vestibulospinal tract)  Cerebellum Integrates massive sensory inputs from many regions of brain and spinal cord: to smoothly coordinate ongoing movements to participate in motor planning Cerebellum has no direct connections to lower motor neurons (except perhaps fastigial nucleus) but has connections to motor systems in cortex and brainstem TABLE 15.1 Functional Regions of the Cerebellum Region Functions Motor pathways influenced Lateral hemispheres Motor planning for extremities Lateral corticospinal tract Intermediate hemispheres Distal limb coordination Lateral corticospinal tract, rubrospinal tract Vermis and flocculonodular lobe Proximal limb and trunk Anterior corticospinal tract, coordination reticulospinal tract, vestibulospinal tract, tectospinal tract Balance and vestibulo-ocular Medial longitudinal fasciculus reflexes Figure 12.19 Vestibular Nuclei and Vestibular Tracts Vestibulocerebellum (inferior vermis, flocculonodular lobes for balance and eye movements) TABLE 15.2 Main Cerebellar Output Pathways Main output targets or Region Deep nuclei Cerebellar peduncle equivalent Lateral hemispheres Dentate nucleus Superior cerebellar Ventrolateral nucleus of peduncle thalamus (VL), parvocellular red nucleus Intermediate hemispheres Interposed nuclei Superior cerebellar VL, magnocellular red peduncle nucleus Vermis Fastigial nuclei Superior cerebellar VL, tectum peduncle Uncinate fasciculus,a Reticular formation, juxtarestiform body b vestibular nuclei Inferior vermis and Vestibular nuclei Juxtarestiform body b Medial longitudinal flocculonodular lobe fasciculus (eye movement pathways) a The uncinate fasciculus travels with the superior cerebellar peduncle. b The juxtarestiform body travels with the inferior cerebellar peduncle. FIGURE 15.9 Cerebellar Output Pathways (Part 1) Note: lateral cerebellum – thalamus – prefrontal cortex – cognition! (corticospinal) Lateral hemispheres Motor control  A loop…. Lateral cerebellum Motor learning (loop) (parvocellular) FIGURE 15.9 Cerebellar Output Pathways (Part 2) Intermediate hemispheres Lateral corticospinal tract Motor control ongoing movements Movement of contralateral limbs (magnocellular) FIGURE 15.9 Cerebellar Output Pathways (Part 3) Vermis + flocculonodular lobes Anterior corticospinal tract Rostral: vestibular Caudal: saccadic eye Vestibulospinal tract Reticulospinal tract (automatic posture FIGURE 15.10 Somatotopic Organization of Multimodal Inputs to the Cerebellum Dorsal/cuneocerebellar tract to vermis Lobules 1,2,4,6, 9  Cerebellar input pathways Inputs arise from widespread areas in CNS Virtually all areas of the cerebral cortex Multiple sensory modalities (somatosensory, vestibular, auditory, visual) Brainstem nuclei Spinal cord TABLE 15.3 Main Cerebellar Input Pathways Cells projecting to Cerebellar peduncle or Input pathway Main origin(s) of input cerebellum equivalent Pontocerebellar fibers Cortex Pontine nuclei Middle cerebellar peduncle Spinocerebellar pathways Dorsal spinocerebellar Leg proprioceptors Nucleus dorsalis of Clark Inferior cerebellar peduncle tract Cuneocerebellar tract Arm proprioceptors External cuneate nucleus Inferior cerebellar peduncle Ventral spinocerebellar Leg interneurons Spinal cord neurons Superior cerebellar tract peduncle Rostral spinocerebellar Arm interneurons Spinal cord neurons Superior and inferior tract cerebellar peduncles Climbing fibers Red nucleus, cortex, Inferior olivary nucleus Inferior cerebellar peduncle brainstem, spinal cord Vestibular inputs Vestibular system Vestibular ganglia, Juxtarestiform body vestibular nuclei  Cerebellar input pathways Next to pontocerebellar fibers: Dorsal spinocerebellar tract: lower extremity movements Cuneocerebellar tract: upper extremity movements (unconscious information from extremities to cerebellum) Ventral spinocerebellar tract (leg) Rostral spinocerebellar tract (arm) Information about activity spinal cord interneurons, reflecting amount of activity in descending pathways Figure 7.4 Spinal Cord Sensory and Motor Spinal Cord Pathways Figure 7.4 Spinal Cord Sensory and Motor Spinal Cord Pathways Afferent information limb movement (leg) Cuneocerebellar : arm) Information about spinal cord interneurons Lower extremity (rostral spinocerebellar: arm) FIGURE 15.11 Spinocerebellar Pathways (Upper extremity) C8-L2 Ventrolateral fasciculus (Lower extremity)  Cerebellar lesions Ataxia: ipsilateral to side of lesion Midline lesions vermis + flocculonodular lobes: unsteady gait (truncal ataxia) and eye movement abnormalities Lesions lateral to the vermis: ataxia of limbs (appendicular ataxia) Note: also articulation of speech, respiratory movements, motor learning, higher cognitive processes