Quiz 3 Practice

Basal Ganglia and Cerebellum link the

association cortex with the primary motor cortex

Compromised of the caudate nucleus, the putamen, and the globus pallidus (together they form the striatum)

• Input goes to all three, output mostly from globus pallidus

• Acts as a filter to prevent unwanted movements

Basal Ganglia

The Basal Ganglia functions with and is dependent on

dopamine

Dopamine is produced in the

substantia nigra

Functions of the Basal Ganglia:

• Regulates muscle tone

• Controls postural adjustments during writing

• Involved and in planning and refining of slow, continuous movement

• Regulate movements that support goal directed activities

• Scales the force, amplitude, and duration of movement

• Assists in learning, preparation, and initiation of movements

Lesions in the Basal Ganglia lead to these two major types of movement disorders

Hypokinesia and Hyperkinesia

Hypokinesia

too little movement; initiation of movement affected

often accompanied by muscular rigidity

Parkinson’s disease

Hyperkinesia

excessive involuntary movement; continuation and stopping of movement affected

Huntington’s disease

Types of Movement Disorders Associated with the Basal Ganglia

Dyskinesia

Myoclonus

Tics

Ballismus

Chorea

Dystonia

Tremor

Dyskinesia

abnormal, involuntary movements

prolonged use of antipsychotic drugs

Myoclonus

involuntary single or repetitive rhythmic or nonrhythmic body jerks

Can be palatal or palatopharyngolaryngeal

Hiccups

Tics

rapid, coordinated, stereotyped movements under partial voluntary control

Tourette’s Syndrome

Ballismus

Gross contractions causing wild flailing movements

Chorea

involuntary rapid, nonstereotypic random purposeless movements

Dystonia

involuntary , abnormal postures

co-contraction of agonist and antagonistic muscles

Can be action-induced or task-specific (writer’s cramp)

Torticollis

Tremor

Rhythmic movement of body parts

Most common involuntary movement

Can be resting or action

Cerebellum

Center for the control of coordinated movement; maintains muscle tone and balance; provides coordination of rapid, alternating movements

Receives input from the association cortex, vestibular labyrinth, visual, tactile, and proprioceptive sensory receptors throughout the body

Decomposition of movement

components of a motor act are performed in a jerky and irregular manner rather than in a smooth sequence

Dysmetria

inability to gauge distance, speed and power of movement; may stop before reaching the target or overshoot the target

Dyssynergia

loss of coordination

Ataxia

combined effects of decomposition, dysmetria, dyssynergia

Thalamus

Important subcortical gray matter structure

Doorway through which subcortical systems of nervous system communicate with cerebral cortex

Believed to use sensory information to further refine motor impulses

Primary Motor Cortex

Receives neural motor impulses that have been processed, smoothed, and coordinated by basal ganglia, cerebellum, and thalamus

Descending Motor Tracts

From cortex to brainstem and spinal cord

Includes Pyramidal and Extrapyramidal Systems

Pyramidal system - Direct Activation Pathway

Carries impulses that control voluntary, fine motor movements

Works at a conscious level

Extrapyramidal system

Carries impulses that control postural support needed by fine motor movements

Works at more of an unconscious level, automatic in function

The Pyramidal and Extrapyramidal system are both considered a part of the _______.

Upper Motor Neuron System

_____ tract fibers provide direct motor innervation to motor nuclei of cranial nerves V, VII, IX, X, XI, and XII

Corticobulbar

_____ tract fibers have direct connection to spinal nerves in anterior horn of spinal cord including those serving respiration.

Corticospinal