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MOTOR SYSTEMS: THE BRAIN
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