Chapter Ten

Motor Control Hierarchy

Levels of brain control for movement execution.

Voluntary Movements

Conscious actions directed by attention.

Involuntary Movements

Unconscious, automatic, or reflex actions.

Local Control Systems

Adjust movements based on sensory information.

Interneurons

Neurons that connect motor and sensory pathways.

Length Monitoring Systems

Systems that monitor muscle length changes.

Muscle Spindle

Stretch receptors that detect muscle length.

Alpha Motor Neurons

Innervate extrafusal muscle fibers for contraction.

Gamma Motor Neurons

Innervate intrafusal fibers for muscle length feedback.

Alpha-Gamma Coactivation

Maintains continuous muscle length information.

Stretch Reflex

Muscle contraction triggered by stretching.

Knee-Jerk Reflex

Monosynaptic reflex involving patellar tendon tap.

Golgi Tendon Organ

Monitors tension in tendons during muscle contraction.

The Withdrawal Reflex

Muscle response to painful stimuli for protection.

Cerebral Cortex

Critical for planning voluntary movements.

Sensorimotor Cortex

Cortex area controlling muscle movement coordination.

Somatotopic Map

Representation of body parts in the brain.

Subcortical Nuclei

Structures that establish movement sequences.

Parkinson Disease

Movement disorder with tremors and rigidity.

Substantia Nigra

Dopamine-producing nucleus affecting motor control.

Cerebellum

Coordinates movement and timing for motor programs.

Corticospinal Pathways

Descending pathways from the cerebral cortex.

Muscle Tone

Resistance to stretch in relaxed muscles.

Center of Gravity

Point where body weight is balanced.

Walking

Coordinated muscle activity initiated by forward motion.