Neural Bases of Human Movement: Basic Concepts of Motor Control

Comprehensive vocabulary flashcards covering the neuroanatomical structures, physiological mechanisms, and sensory-motor pathways of human motor control.

Motor Control

The study of neural, physical, and behavioral aspects of movement, focusing on how motor skills are executed and the factors leading to skill breakdown.

Motor Development

The study of how the acquisition, improvement, and control of motor skills change and vary across the human lifespan.

Motor Learning

The study of how motor skills are learned and acquired, particularly examining the conditions and practice variables that lead to improvement.

Central Nervous System (CNS)

The division of the nervous system encompassing the brain and spinal cord, serving as the primary sites of information processing.

Peripheral Nervous System (PNS)

The division of the nervous system consisting of afferent pathways relaying sensory signals toward the CNS and efferent pathways relaying motor signals away from the CNS.

Somatic Sensory Receptors

Peripheral receptors that monitor skeletal muscles, joints, and skin to provide sensations of position, touch, pressure, pain, and temperature.

Visceral Sensory Receptors

Sensory receptors monitoring internal organs within the cardiovascular, respiratory, and digestive systems.

Anaxonic Neuron

A neuron with multiple processes where axons cannot be distinguished anatomically from dendrites.

Bipolar Neuron

A neuron possessing two distinct processes extending from opposite sides of the cell body: one dendrite and one axon.

Pseudounipolar Neuron

A neuron with a single process emerging from the cell body that branches into a continuous axon connecting dendrites directly to the synaptic terminals.

Multipolar Neuron

A neuron possessing multiple dendrites and a single elongated axon extending from the cell body, commonly found among motor neurons and interneurons.

First-Order Sensory Neuron

The primary sensory neuron that detects a stimulus and delivers sensory input directly to the central nervous system.

Second-Order Sensory Neuron

An interneuron located in the spinal cord or brain stem that receives sensory input from a first-order neuron and relays it rostrally.

Third-Order Sensory Neuron

A sensory neuron located in the thalamus that carries sensory information to the sensory cortex of the cerebrum, required for conscious sensation.

Upper Motor Neuron

A motor neuron originating in the cerebrum, thalamus, or brain stem that delivers motor commands down to CNS motor nuclei in the brainstem or spinal cord.

Lower Motor Neuron

An efferent neuron located in the brainstem or ventral horn of the spinal cord whose axon innervates a single motor unit within a skeletal muscle.

Interneurons

Association or relay neurons located strictly within the CNS that integrate incoming sensory information and relay impulses to motor neurons.

Converging Circuit

A synaptic arrangement where inputs from multiple distinct presynaptic neurons synapse onto a single postsynaptic neuron, such as multiple brain centers converging on an alpha motor neuron.

Diverging Circuit

A synaptic arrangement where an incoming signal from a single presynaptic neuron branches out to stimulate multiple postsynaptic neurons or pathways.

Reverberating Circuit

A neuronal circuit utilizing positive feedback loops to repeatedly reactivate upstream neurons, supporting rhythmic activities such as breathing or locomotion.

Parallel After-Discharge Circuit

A neural circuit in which an input neuron stimulates parallel chains of differing lengths that converge on a common output cell, crucial for precise activities like mathematical calculations.

Neuroglia

Non-neuronal support cells that protect, nourish, and insulate neurons, comprising roughly half the volume of the nervous system and outnumbering neurons by approximately 5 to 1.

Saltatory Conduction

The rapid propagation of action potentials jumping along myelinated axons from one node of Ranvier to the next.

Kinesthetic System

The sensory system responsible for conscious and subconscious awareness of body position and movement, using mechanoreceptors such as spindles, GTOs, and joint receptors.

Muscle Spindle

A fluid-filled capsule ($1\text{--}4\,\text{mm}$ long) lying parallel to extrafusal muscle fibers that detects changes in muscle length and the velocity of stretch.

Intrafusal Fibres

Specialized, modified muscle fibers situated inside the muscle spindle capsule that are innervated by gamma motor neurons.

Nuclear Bag Fibers

Intrafusal muscle spindle fibers whose primary role is sensing and responding to the dynamic rate or velocity of muscle stretch.

Nuclear Chain Fibers

Intrafusal muscle spindle fibers that monitor and respond primarily to the static length of a muscle.

Alpha-Gamma Coactivation

The simultaneous stimulation of alpha and gamma motor neurons during voluntary contraction, maintaining spindle tension and sensory sensitivity as the muscle shortens.

Golgi Tendon Organ (GTO)

A proprioceptor situated in-series at the musculotendinous junction that responds to active muscle tension and tendon strain.

Pacinian Corpuscles

Encapsulated skin and joint receptors specialized for detecting deep pressure and high-frequency vibration.

Stretch (Myotatic) Reflex

A monosynaptic spinal reflex triggered by muscle spindle afferents that causes contraction of the stretched muscle and reciprocal inhibition of its antagonist.

Flexion Reflex

A polysynaptic spinal reflex that produces rapid withdrawal of an entire limb away from a noxious or painful stimulus.

Crossed Extensor Reflex

A contralateral spinal reflex occurring alongside the flexion withdrawal reflex that stimulates extension in the opposing limb to maintain upright balance.

Extensor Thrust Reflex

A spinal reflex provoked by cutaneous pressure receptors on the plantar surface of the foot that triggers extension of the lower extremity.

Motor Homunculus

A distorted topographical map across the precentral gyrus depicting disproportionately large cortical areas for body parts requiring fine, precise motor control.

Pyramidal Tract

The direct descending corticospinal pathway mediating conscious voluntary control of skeletal musculature via primarily excitatory upper motor neuron signals.

Extrapyramidal Tracts

Indirect descending motor pathways that subconscious regulate muscle tone, postural adjustments, and spinal reflexes via primarily inhibitory influences.

Cerebellum

The brain region termed 'the seat of motor coordination' that oversees equilibrium, movement timing, and motor learning by comparing intended actions with sensory feedback.

Purkinje Neuron

A large cerebellar cortex neuron characterized by an extensively branched, fan-like dendritic arbor that delivers inhibitory output to the deep cerebellar nuclei.

Ataxia

A clinical symptom of cerebellar dysfunction manifested as an inability to coordinate voluntary muscle movements, leading to unsteady gait and poor limb control.

Basal Nuclei

Subcortical nuclei within the cerebrum and midbrain responsible for retrieving, initiating, and scaling movements while suppressing unwanted motor patterns.

Parkinson's Disease

A neurodegenerative disorder characterized by a hypokinetic gait caused by a deficiency of dopamine within the basal ganglia.

Huntington's Disease

An inherited neurodegenerative condition characterized by hyperkinetic movements and dementia caused by the death of neurons within the basal ganglia.

Red Nucleus

A midbrain motor nucleus involved in the extrapyramidal rubrospinal pathway that assists with the subconscious control of gait.

Tectum

A dorsal brainstem region comprising the superior and inferior colliculi that processes visual and auditory stimuli to guide orienting reflexes.

Vestibular Nucleus

A brainstem nucleus that receives inner ear input and works alongside the cerebellum to modify muscle tone, equilibrium, and posture.

Reticular Formation

A diffuse brainstem network whose ascending projections regulate cortical arousal and whose descending projections modulate spinal cord reflex excitability.