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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