Motor Controls Voluntary Control of Movement
• One main FUNCTION of the BRAIN is to DIRECT the BODY'S PURPOSEFUL INTERACTION WITH its
ENVIRONMENT
• Adaptive neural circuitry = allows mammals to interact in sophisticated ways
• ADAPTIVE PATTERNING of VOLUNTARY MOVEMENTS gives MAMMALS a DISTINCT ADVANTAGE in locating food,
finding mates, and avoiding predators
• Voluntary movements differ from reflexes: THEY ARE INITIATED BY A DELIBERATE INTERNAL DECISION
• REFLEXES are INITIATED AUTOMATICALLY by EXTERNAL STIMULI
• Motor cortices are LOCATED in the FRONTAL HALF of the BRAIN (anterior)
• Motor cortices work together to CONTROL DIFFERENT ASPECTS OF
MOVEMENT
• Motor cortices consist of multiple cortical areas:
1. Premotor area
2. Supplemental motor area
3. Primary motor cortex (M1)
4. Prefrontal cortex (PFC)
• The motor cortices SEND AXONS via the DESCENDING CORTICOSPINAL TRACTS to the
spinal cord
• There AXON SYNAPSE ONTO MOTOR NEURONS of the spinal cord
• CONTROL OF VOLUNTARY MOVEMENT
• DESCENDING SPINAL TRACTS are divided into LATERAL and VENTROMEDIAL PATHWAYS
LATERAL PATHWAYS:
• Corticospinal and rubrospinal tracts
• VOLUNTARY MOVEMENT of distal musculature (limbs)
• Direct cortical control
VENTROMEDIAL PATHWAYS:
• Control of posture and locomotion
• Controlled by the brainstem
Integration of Physiological Systems Page 1
, VENTROMEDIAL PATHWAYS:
• Control of posture and locomotion
• Controlled by the brainstem
CORTICOSPINAL TRACT
• Longest axons in the CNS
• Largely ORIGINATE in PRIMARY MOTOR CORTEX
• Axons pass through: internal capsule, midbrain, medulla to the spinal cord
• AXONS DECUSSATE (cross to the other half of the body) IN the PYRAMIDAL
DECUSSATION
RUBROSPINAL TRACT
• ORIGINATES in the red NUCLEUS of the MIDBRAIN
• RECEIVES SIMILAR INPUTS from MOTOR CORTICES
• FUNCTION largely OVERTAKEN by CORTICOSPINAL TRACT
• DEMYELINATION of axons LEADS to IMPAIRED SIGNALLING
• Demyelination is VISIBLE AS LESIONS in fMRI imaging
• Lesions CAUSE SLOW WORSENING of MOTOR IMPAIRMENTS in patients as it mainly AFFECTS CORTICOSPINAL
TRACTS
VESTIBULOSPINAL TRACTS
• ORIGINATES in the VESTIBULAR NUCLEUS (processes sensory information
from the ear)
• KEEPS HEAD STEADY and BALANCED during BODY MOVEMENTS
• Innervates muscles in the neck and back
TECTOSPINAL TRACTS
• ORIGINATES in the SUPERIOR COLLICULUS (SC)
• SC receives input from the retina and visual cortices
• HELPS to GUIDE ORIENTATION of the BODY TOWARDS RELEVANT
STIMULI
• Innervates muscles neck, upper trunk and shoulder
RETICULOSPINAL TRACTS
• ORIGINATE in the RETICULAR FORMATION motor functions through
PONTINE RETICULOSPINAL TRACT
• ORIGINATE in the PONTINE RETICULAR FORMATION
Integration of Physiological Systems Page 2
• One main FUNCTION of the BRAIN is to DIRECT the BODY'S PURPOSEFUL INTERACTION WITH its
ENVIRONMENT
• Adaptive neural circuitry = allows mammals to interact in sophisticated ways
• ADAPTIVE PATTERNING of VOLUNTARY MOVEMENTS gives MAMMALS a DISTINCT ADVANTAGE in locating food,
finding mates, and avoiding predators
• Voluntary movements differ from reflexes: THEY ARE INITIATED BY A DELIBERATE INTERNAL DECISION
• REFLEXES are INITIATED AUTOMATICALLY by EXTERNAL STIMULI
• Motor cortices are LOCATED in the FRONTAL HALF of the BRAIN (anterior)
• Motor cortices work together to CONTROL DIFFERENT ASPECTS OF
MOVEMENT
• Motor cortices consist of multiple cortical areas:
1. Premotor area
2. Supplemental motor area
3. Primary motor cortex (M1)
4. Prefrontal cortex (PFC)
• The motor cortices SEND AXONS via the DESCENDING CORTICOSPINAL TRACTS to the
spinal cord
• There AXON SYNAPSE ONTO MOTOR NEURONS of the spinal cord
• CONTROL OF VOLUNTARY MOVEMENT
• DESCENDING SPINAL TRACTS are divided into LATERAL and VENTROMEDIAL PATHWAYS
LATERAL PATHWAYS:
• Corticospinal and rubrospinal tracts
• VOLUNTARY MOVEMENT of distal musculature (limbs)
• Direct cortical control
VENTROMEDIAL PATHWAYS:
• Control of posture and locomotion
• Controlled by the brainstem
Integration of Physiological Systems Page 1
, VENTROMEDIAL PATHWAYS:
• Control of posture and locomotion
• Controlled by the brainstem
CORTICOSPINAL TRACT
• Longest axons in the CNS
• Largely ORIGINATE in PRIMARY MOTOR CORTEX
• Axons pass through: internal capsule, midbrain, medulla to the spinal cord
• AXONS DECUSSATE (cross to the other half of the body) IN the PYRAMIDAL
DECUSSATION
RUBROSPINAL TRACT
• ORIGINATES in the red NUCLEUS of the MIDBRAIN
• RECEIVES SIMILAR INPUTS from MOTOR CORTICES
• FUNCTION largely OVERTAKEN by CORTICOSPINAL TRACT
• DEMYELINATION of axons LEADS to IMPAIRED SIGNALLING
• Demyelination is VISIBLE AS LESIONS in fMRI imaging
• Lesions CAUSE SLOW WORSENING of MOTOR IMPAIRMENTS in patients as it mainly AFFECTS CORTICOSPINAL
TRACTS
VESTIBULOSPINAL TRACTS
• ORIGINATES in the VESTIBULAR NUCLEUS (processes sensory information
from the ear)
• KEEPS HEAD STEADY and BALANCED during BODY MOVEMENTS
• Innervates muscles in the neck and back
TECTOSPINAL TRACTS
• ORIGINATES in the SUPERIOR COLLICULUS (SC)
• SC receives input from the retina and visual cortices
• HELPS to GUIDE ORIENTATION of the BODY TOWARDS RELEVANT
STIMULI
• Innervates muscles neck, upper trunk and shoulder
RETICULOSPINAL TRACTS
• ORIGINATE in the RETICULAR FORMATION motor functions through
PONTINE RETICULOSPINAL TRACT
• ORIGINATE in the PONTINE RETICULAR FORMATION
Integration of Physiological Systems Page 2
