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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
RETICULAR
FORMATION
LATERAL
AND MEDIAL
VESTIBULAR
NUCLEI
RED NUCLEUS
MEDIAL
RETICULAR
FORMATION
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
PATHWAYS FROM BRAINSTEM FOR
MOTOR CONTROL: VENTROMEDIAL
TECTOSPINAL
TRACT
VESTIBULOSPINAL
TRACTS
RETICULOSPINAL
TRACT
LOCATION OF CELL BODIES FOR
EXTENSORS AND FLEXORS
FLEXORS
EXTENSORS
THE LATERAL
RETICULOSPINAL TRACT
FROM LATERAL RETICULAR NUCLEUS
DESCEND IN LATERAL REGION OF THE
SPINAL CORD
PATHWAYS FROM BRAINSTEM FOR MOTOR
CONTROL:LATERAL RETICULOSPINAL TRACT
LATERAL
RETICULOSPINAL
TRACT
THE RUBROSPINAL
TRACTH
FIBERS ORIGINATE IN RED NUCLEUS
DESCEND ALONG DORSAL AND LATERAL
BORDERS OF CORD
INNERVATE DISTAL FLEXOR MUSCLES
PATHWAYS FROM BRAINSTEM FOR
MOTOR CONTROL: RUBROSPINAL
SUMMARY OF CONTROL OF SPINAL
MOTOR NEURONS BY BRAIN STEM
LATERAL
RETICULOSPINAL TRACT
RUBROSPINAL
TRACT
(-)
(+)
TO FLEXORS
TO EXTENSORS
(-)
(
(+) )
VENTROMEDIAL
PATHWAY
TO FLEXORS
TO EXTENSORS
THE MOTOR CORTEX
ORGANIZATION
DESCENDING PATHWAYS
SENSORY FEEDBACK
CORTICAL CODING OF REACHING
MOVEMENTS
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
CORTICAL AREAS INVOVED
IN MOTOR CONTROL
SOMATOTOPIC ORGANIZATION
OF THE MOTOR CORTEX
DESCENDING PATHWAYS
FROM THE MOTOR CORTEX
CORTICOSPINAL PATHWAY
CORTICOBULBAR PATHWAY
PYRAMIDAL TRACT
LATERAL CORTICOSPINAL TRACT
PATHWAYS FROM CORTEX FOR MOTOR
CONTROL: LATERAL CORTICOSPINAL TRACT
LATERAL
CORTICOSPINAL
TRACT
DORSAL
COLUMN
NUCLEI
PREMOTOR
AREA
RED
NUCLEUS
1
2
3
PYRAMIDAL
TRACT
4
6
PRIMARY
MOTOR
CORTEX
PATHWAYS FROM CORTEX FOR MOTOR
CONTROL: CORTICOSPINAL TRACTS
LATERAL
CORTICOSPINAL
TRACT
DORSAL
COLUMN
NUCLEI
PREMOTOR
AREA
RED
NUCLEUS
1
2
3
VENTRAL
CORTICOSPINAL
TRACT
PYRAMIDAL
TRACT
4
6
PRIMARY
MOTOR
CORTEX
SENSORY FEEDBACK TO THE
MOTOR CORTEX
VIA SOMATIC SENSORY CORTEX
CONNECTED IN A TOPOGRAPHIC
MANNER
MONITOR MOVEMENT AND SMOOTH AND
CORRECT
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)
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
POSTERIOR PARIETAL CORTEX INTEGRATES
SENSORY STIMULI FOR PURPOSEFUL
MOVEMENT
RECEIVES BOTH SOMATIC AND VISUAL
SENSORY INFORMATION
TRANSMITS IT TO SUPPLIMENTAL AND
PREMOTOR AREAS
CORTICAL AREAS INVOVED
IN MOTOR CONTROL
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
FUNCTIONS OF THE
CEREBELLUM
PLANNING OF A MOVEMENT
CONTROL OF POSTURE AND
EQUILIBRIUM
CONTROL OF SMOOTH LIMB MOVEMENT
CELL TYPES AND CIRCUITS
IN THE CEREBELLUM
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
THE BASAL GANGLIA
THE BASAL GANGLIA PLAN
MOVEMENTS
PRIMARY INPUT FROM NEOCORTEX
OTHER INPUTS FROM THE THALAMUS
AND SUBSTANTIA NIGRA
GLOBUS PALLIDUS PROVIDES OUTPUT
COGNITIVE FUNCTIONS
BASAL GANGLIA:
AFFERENT CONNECTIONS
CORTEX
CAUDATE
THALAMUS
PUTAMEN
SUBSTANTIA
NIGRA
BASAL GANGLIA: INTRINSIC
CONNECTIONS
CORTEX
CAUDATE
THALAMUS
PUTAMEN
GLOBUS
PALLIDUS
SUBSTANTIA
NIGRA
BASAL GANGLIA: EFFERENT
CONNECTIONS
CAUDATE
THALAMUS
PUTAMEN
GLOBUS
PALLIDUS
SUBSTANTIA
NIGRA
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
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
DISEASES OF THE MOTOR
SYSTEM
UPPER-MOTOR-NEURON LESIONS
CORTICOSPINAL TRACT LESIONS
LOWER MOTOR NEURON LESIONS
CEREBELLAR LESIONS
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
CORTICOSPINAL TRACT
LESIONS
LOSS OF STRENGTH AND MOVEMENT OF
MUSCLE GROUPS
LOSS OF STRENGTH IN VOLUNTARY
MUSCLE CONTRACTION
BABINSKI SIGN
LOWER MOTOR NEURON
LESIONS
IPSOLATERAL HYPOACTIVE REFLEXES
PARALYSIS
FLACID MUSCLES WITH PROMINENT
ATROPHY
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