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

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Presentation on theme: "MOTOR SYSTEMS:POSTURE AND LOCOMOTION D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM."— Presentation transcript:

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

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

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

4 THE VENTROMEDIAL PATHWAY zVESTIBULOSPINAL TRACT: CARRIES INFORMATION FROM VESTIBULAR NUCLEUS FOR REFLEX CONTROL OF EQUILIBRIUM zTECTOSPINAL TRACT: ORIGINATES IN TECTUM FOR CONTROL OF HEAD AND EYE MOVEMENTS zMEDIAL RETICULOSPINAL TRACT: ORIGINATES IN RETICULAR FORMATION FOR MAINTAINING POSTURE BY ACTIVATION OF EXTENSORS

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

6 LOCATION OF CELL BODIES FOR EXTENSORS AND FLEXORS FLEXORS EXTENSORS

7 THE LATERAL RETICULOSPINAL TRACT zFROM LATERAL RETICULAR NUCLEUS zDESCEND 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 zFIBERS ORIGINATE IN RED NUCLEUS zDESCEND ALONG DORSAL AND LATERAL BORDERS OF CORD zINNERVATE DISTAL FLEXOR MUSCLES

10 PATHWAYS FROM BRAINSTEM FOR MOTOR CONTROL: RUBROSPINAL

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

12 THE MOTOR CORTEX zORGANIZATION zDESCENDING PATHWAYS zSENSORY FEEDBACK zCORTICAL CODING OF REACHING MOVEMENTS

13 ORGANIZATION OF THE MOTOR CORTEX zCORTICAL EFFERENT ZONES: VERTICAL COLUMNS OF CELLS zEACH ZONE CONTROLS ONE MUSCLE zSIX DIFFERENT LAYERS OF CELLS zOUTPUT LAYER IS LAYER V zEXCITE BOTH ALPHA AND GAMMA MOTOR NEURONS

14 CORTICAL AREAS INVOVED IN MOTOR CONTROL

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16 SOMATOTOPIC ORGANIZATION OF THE MOTOR CORTEX

17 DESCENDING PATHWAYS FROM THE MOTOR CORTEX zCORTICOSPINAL PATHWAY zCORTICOBULBAR PATHWAY zPYRAMIDAL TRACT zLATERAL CORTICOSPINAL TRACT

18 PATHWAYS FROM CORTEX FOR MOTOR CONTROL: LATERAL CORTICOSPINAL TRACT 123123 6 4 PREMOTOR AREA PRIMARY MOTOR CORTEX PYRAMIDAL TRACT DORSAL COLUMN NUCLEI LATERAL CORTICO- SPINAL TRACT RED NUCLEUS

19 PATHWAYS FROM CORTEX FOR MOTOR CONTROL: CORTICOSPINAL TRACTS 123123 6 4 PREMOTOR AREA PRIMARY MOTOR CORTEX PYRAMIDAL TRACT DORSAL COLUMN NUCLEI LATERAL CORTICO- SPINAL TRACT RED NUCLEUS VENTRAL CORTICO- SPINAL TRACT

20 SENSORY FEEDBACK TO THE MOTOR CORTEX zVIA SOMATIC SENSORY CORTEX zCONNECTED IN A TOPOGRAPHIC MANNER zMONITOR MOVEMENT AND SMOOTH AND CORRECT

21 CORTICAL CODING OF REACHING MOVEMENTS zDYNAMIC NEURONS CODE FOR RATE OF FORCE DEVELOPMENT zSTEADY STATE FORCE zNEURONS CONTROLLING RATE AND DIRECTION OF MOVEMENT ARE DISTRIBUTED (NO ONE NEURON HAS ALL THE INFORMATION)

22 SUPPLIMENTAL MOTOR AREAS PROGRAM MOVEMENT zHYPOTHALAMUS INVOLVED IN MOTIVATIONAL FACTORS zTRANSMIT INFORMATION TO SUPPLIMENTAL AND PREMOTOR CORTEX zHERE THE DESIGN OF THE MOVEMENT IS EXECUTED zREHERSAL OF MOVEMENTS AS WELL

23 POSTERIOR PARIETAL CORTEX INTEGRATES SENSORY STIMULI FOR PURPOSEFUL MOVEMENT zRECEIVES BOTH SOMATIC AND VISUAL SENSORY INFORMATION zTRANSMITS IT TO SUPPLIMENTAL AND PREMOTOR AREAS

24 CORTICAL AREAS INVOVED IN MOTOR CONTROL

25 THE CEREBELLUM AND BASAL GANGLIA COORDINATE MOVEMENTS zTHE CEREBELLUM IS INVOLVED IN PLANNING, COORDINATION, AND POSTURE zANTERIOR AND POSTERIOR LOBES INVOLVED IN LIMB MOVEMENT zFLOCCULONODULAR LOBE IS INVOLVED IN EQUILIBRIUM AND POSTURE

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27 FUNCTIONS OF THE CEREBELLUM zPLANNING OF A MOVEMENT zCONTROL OF POSTURE AND EQUILIBRIUM zCONTROL OF SMOOTH LIMB MOVEMENT

28 CELL TYPES AND CIRCUITS IN THE CEREBELLUM

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

30 THE BASAL GANGLIA

31 THE BASAL GANGLIA PLAN MOVEMENTS zPRIMARY INPUT FROM NEOCORTEX zOTHER INPUTS FROM THE THALAMUS AND SUBSTANTIA NIGRA zGLOBUS PALLIDUS PROVIDES OUTPUT zCOGNITIVE FUNCTIONS

32 BASAL GANGLIA: AFFERENT CONNECTIONS CORTEX CAUDATE THALAMUS PUTAMEN SUBSTANTIA NIGRA

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

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

35 BASAL GANGLIA OUTPUT TO CORTEX VIA THALAMUS zMODULATE DESCENDING COMPONENTS OF THE MOTOR SYSTEM zADDITIONAL OUTPUTS TO SUBSTANTIA NIGRA USE DOPAMINE AS NEUROTRANSMITTER: THESE DEGENERATE IN PARKINSON’S DISEASE

36 THE VESTIBULAR APPARATUS zSEMICIRCULAR CANALS: HAIR CELLS SENSE MOTION zTHREE COORDINATE PLANES: SUPERIOR, INFERIOR, AND HORIZONTAL zUTRICLE AND SACCULE DETECT LINEAR ACCELERATION IN HORIZONTAL AND VERTICLE PLANES

37 DISEASES OF THE MOTOR SYSTEM zUPPER-MOTOR-NEURON LESIONS zCORTICOSPINAL TRACT LESIONS zLOWER MOTOR NEURON LESIONS zCEREBELLAR LESIONS

38 UPPER-MOTOR-NEURON LESIONS zPARALYSIS ON SIDE OF BODY OPPOSITE LESION zINCREASED MUSCLE TONE zEXTENSION OF BIG TOE AND BABINSKI SIGN zLACK OF MUSCLE ATROPHY

39 CORTICOSPINAL TRACT LESIONS zLOSS OF STRENGTH AND MOVEMENT OF MUSCLE GROUPS zLOSS OF STRENGTH IN VOLUNTARY MUSCLE CONTRACTION zBABINSKI SIGN

40 LOWER MOTOR NEURON LESIONS zIPSOLATERAL HYPOACTIVE REFLEXES zPARALYSIS zFLACID MUSCLES WITH PROMINENT ATROPHY

41 CEREBELLAR LESIONS zIPSILATERAL DISTURBANCES zLATERAL LESIONS RESULT IN COORDINATION LOSS zLESIONS IN THE VERMIS PRODUCE ATAXIA (LOSS OF COORDINATION) zFLOCCULONODULAR LOBE LESIONS PRODUCE EQUILIBRIUM DISTURBANCE AND ATAXIA


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