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MOTOR SYSTEMS:POSTURE AND LOCOMOTION

MOTOR SYSTEMS:POSTURE AND LOCOMOTION. D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM. CONTROL OF POSTURE BY THE BRAIN STEM. THE VENTROMEDIAL PATHWAY THE LATERAL RETICULOSPINAL TRACT THE RUBROSPINAL TRACTH. BRAIN STEM CENTERS FOR MOTOR CONTROL. TECTUM. LATERAL

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MOTOR SYSTEMS:POSTURE AND LOCOMOTION

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  1. MOTOR SYSTEMS:POSTURE AND LOCOMOTION D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM

  2. CONTROL OF POSTURE BY THE BRAIN STEM • THE VENTROMEDIAL PATHWAY • THE LATERAL RETICULOSPINAL TRACT • THE RUBROSPINAL TRACTH

  3. BRAIN STEM CENTERS FOR MOTOR CONTROL TECTUM LATERAL RETICULAR FORMATION RED NUCLEUS MEDIAL RETICULAR FORMATION LATERAL AND MEDIAL VESTIBULAR NUCLEI

  4. THE VENTROMEDIAL PATHWAY • VESTIBULOSPINAL TRACT: CARRIES INFORMATION FROM VESTIBULAR NUCLEUS FOR REFLEX CONTROL OF EQUILIBRIUM • TECTOSPINAL TRACT: ORIGINATES IN TECTUM FOR CONTROL OF HEAD AND EYE MOVEMENTS • MEDIAL RETICULOSPINAL TRACT: ORIGINATES IN RETICULAR FORMATION FOR MAINTAINING POSTURE BY ACTIVATION OF EXTENSORS

  5. PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL: VENTROMEDIAL TECTO- SPINAL TRACT VESTIBULO- SPINAL TRACTS RETICULO- SPINAL TRACT

  6. LOCATION OF CELL BODIES FOR EXTENSORS AND FLEXORS FLEXORS EXTENSORS

  7. THE LATERAL RETICULOSPINAL TRACT • FROM LATERAL RETICULAR NUCLEUS • DESCEND IN LATERAL REGION OF THE SPINAL CORD

  8. PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL:LATERAL RETICULOSPINAL TRACT LATERAL RETICULO- SPINAL TRACT

  9. THE RUBROSPINAL TRACTH • FIBERS ORIGINATE IN RED NUCLEUS • DESCEND ALONG DORSAL AND LATERAL BORDERS OF CORD • INNERVATE DISTAL FLEXOR MUSCLES

  10. PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL: RUBROSPINAL

  11. SUMMARY OF CONTROL OF SPINAL MOTOR NEURONS BY BRAIN STEM RUBRO- SPINAL TRACT LATERAL RETICULO- SPINAL TRACT (-) (-) (+) (-) (+) TO FLEXORS TO FLEXORS TO EXTENSORS VENTROMEDIAL PATHWAY TO EXTENSORS

  12. THE MOTOR CORTEX • ORGANIZATION • DESCENDING PATHWAYS • SENSORY FEEDBACK • CORTICAL CODING OF REACHING MOVEMENTS

  13. ORGANIZATION OF THE MOTOR CORTEX • CORTICAL EFFERENT ZONES: VERTICAL COLUMNS OF CELLS • EACH ZONE CONTROLS ONE MUSCLE • SIX DIFFERENT LAYERS OF CELLS • OUTPUT LAYER IS LAYER V • EXCITE BOTH ALPHA AND GAMMA MOTOR NEURONS

  14. CORTICAL AREAS INVOVED IN MOTOR CONTROL

  15. SOMATOTOPIC ORGANIZATION OF THE MOTOR CORTEX

  16. DESCENDING PATHWAYS FROM THE MOTOR CORTEX • CORTICOSPINAL PATHWAY • CORTICOBULBAR PATHWAY • PYRAMIDAL TRACT • LATERAL CORTICOSPINAL TRACT

  17. PATHWAYS FROM CORTEX FOR MOTOR CONTROL: LATERAL CORTICOSPINAL TRACT PREMOTOR AREA LATERAL CORTICO- SPINAL TRACT DORSAL COLUMN NUCLEI RED NUCLEUS 1 2 3 4 6 PRIMARY MOTOR CORTEX PYRAMIDAL TRACT

  18. PATHWAYS FROM CORTEX FOR MOTOR CONTROL: CORTICOSPINAL TRACTS PREMOTOR AREA LATERAL CORTICO- SPINAL TRACT DORSAL COLUMN NUCLEI RED NUCLEUS 1 2 3 4 6 VENTRAL CORTICO- SPINAL TRACT PRIMARY MOTOR CORTEX PYRAMIDAL TRACT

  19. SENSORY FEEDBACK TO THE MOTOR CORTEX • VIA SOMATIC SENSORY CORTEX • CONNECTED IN A TOPOGRAPHIC MANNER • MONITOR MOVEMENT AND SMOOTH AND CORRECT

  20. CORTICAL CODING OF REACHING MOVEMENTS • DYNAMIC NEURONS CODE FOR RATE OF FORCE DEVELOPMENT • STEADY STATE FORCE • NEURONS CONTROLLING RATE AND DIRECTION OF MOVEMENT ARE DISTRIBUTED (NO ONE NEURON HAS ALL THE INFORMATION)

  21. SUPPLIMENTAL MOTOR AREAS PROGRAM MOVEMENT • HYPOTHALAMUS INVOLVED IN MOTIVATIONAL FACTORS • TRANSMIT INFORMATION TO SUPPLIMENTAL AND PREMOTOR CORTEX • HERE THE DESIGN OF THE MOVEMENT IS EXECUTED • REHERSAL OF MOVEMENTS AS WELL

  22. POSTERIOR PARIETAL CORTEX INTEGRATES SENSORY STIMULI FOR PURPOSEFUL MOVEMENT • RECEIVES BOTH SOMATIC AND VISUAL SENSORY INFORMATION • TRANSMITS IT TO SUPPLIMENTAL AND PREMOTOR AREAS

  23. CORTICAL AREAS INVOVED IN MOTOR CONTROL

  24. THE CEREBELLUM AND BASAL GANGLIA COORDINATE MOVEMENTS • THE CEREBELLUM IS INVOLVED IN PLANNING, COORDINATION, AND POSTURE • ANTERIOR AND POSTERIOR LOBES INVOLVED IN LIMB MOVEMENT • FLOCCULONODULAR LOBE IS INVOLVED IN EQUILIBRIUM AND POSTURE

  25. FUNCTIONS OF THE CEREBELLUM • PLANNING OF A MOVEMENT • CONTROL OF POSTURE AND EQUILIBRIUM • CONTROL OF SMOOTH LIMB MOVEMENT

  26. CELL TYPES AND CIRCUITS IN THE CEREBELLUM

  27. PURKINJE CELLS ARE THE MOST PROMINENT OF ALL THE CEREBELLAR CELL TYPES • TWO INPUTS: CLIMBING FIBERS (FROM OLIVARY NUCLEUS) AND PARALLEL FIBERS FROM GRANULE CELLS • OUTPUT VARIES ACORDING TO INPUT: CLIMING FIBERS LEAD TO COMPLEX PATTERNS WHILE PARALLEL FIBERS GENERATE SIMPLE PATTERNS

  28. THE BASAL GANGLIA

  29. THE BASAL GANGLIA PLAN MOVEMENTS • PRIMARY INPUT FROM NEOCORTEX • OTHER INPUTS FROM THE THALAMUS AND SUBSTANTIA NIGRA • GLOBUS PALLIDUS PROVIDES OUTPUT • COGNITIVE FUNCTIONS

  30. BASAL GANGLIA: AFFERENT CONNECTIONS CORTEX CAUDATE THALAMUS PUTAMEN SUBSTANTIA NIGRA

  31. BASAL GANGLIA: INTRINSIC CONNECTIONS CORTEX CAUDATE THALAMUS PUTAMEN GLOBUS PALLIDUS SUBSTANTIA NIGRA

  32. BASAL GANGLIA: EFFERENT CONNECTIONS CAUDATE THALAMUS PUTAMEN GLOBUS PALLIDUS SUBSTANTIA NIGRA

  33. BASAL GANGLIA OUTPUT TO CORTEX VIA THALAMUS • MODULATE DESCENDING COMPONENTS OF THE MOTOR SYSTEM • ADDITIONAL OUTPUTS TO SUBSTANTIA NIGRA USE DOPAMINE AS NEUROTRANSMITTER: THESE DEGENERATE IN PARKINSON’S DISEASE

  34. THE VESTIBULAR APPARATUS • SEMICIRCULAR CANALS: HAIR CELLS SENSE MOTION • THREE COORDINATE PLANES: SUPERIOR, INFERIOR, AND HORIZONTAL • UTRICLE AND SACCULE DETECT LINEAR ACCELERATION IN HORIZONTAL AND VERTICLE PLANES

  35. DISEASES OF THE MOTOR SYSTEM • UPPER-MOTOR-NEURON LESIONS • CORTICOSPINAL TRACT LESIONS • LOWER MOTOR NEURON LESIONS • CEREBELLAR LESIONS

  36. UPPER-MOTOR-NEURON LESIONS • PARALYSIS ON SIDE OF BODY OPPOSITE LESION • INCREASED MUSCLE TONE • EXTENSION OF BIG TOE AND BABINSKI SIGN • LACK OF MUSCLE ATROPHY

  37. CORTICOSPINAL TRACT LESIONS • LOSS OF STRENGTH AND MOVEMENT OF MUSCLE GROUPS • LOSS OF STRENGTH IN VOLUNTARY MUSCLE CONTRACTION • BABINSKI SIGN

  38. LOWER MOTOR NEURON LESIONS • IPSOLATERAL HYPOACTIVE REFLEXES • PARALYSIS • FLACID MUSCLES WITH PROMINENT ATROPHY

  39. CEREBELLAR LESIONS • IPSILATERAL DISTURBANCES • LATERAL LESIONS RESULT IN COORDINATION LOSS • LESIONS IN THE VERMIS PRODUCE ATAXIA (LOSS OF COORDINATION) • FLOCCULONODULAR LOBE LESIONS PRODUCE EQUILIBRIUM DISTURBANCE AND ATAXIA

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