The Motor System and the Cerebellar Function Neurologic System The Motor System and the Cerebellar Function

Motor Pathways & Type of Movements Corticospinal or Pyramidal Tract Voluntary, skilled, discrete, purposeful (writing) Extrapyramidal Tracts Maintain muscle tone and control body movements (walking) Cerebellar System Coordinates movement, maintains equilibrium and posture….Operates on subconsious level Motor nerve fibers in Corticospinal tract originate in cerebral cortex, travel to brain stem, decussation, & move down lateral column spinal cord What type of movements are mediated by The Corticospinal Tract Voluntary, skilled ,discrete movement

Question for Thought Describe 3 major motor pathways in the CNS including the type of movements mediated by each?

Chapter 21 Cerebral Cortex The Motor Pathways consist of the 1. Corticospinal or Pyramidal Tract. In center of cerebral cortex. Note upside down human – Red – Hands Motor nerve fibers originate in the motor cortex and travel to the brain stem where decussation happens and they continue down in the lateral column of the spinal cord. This motor system permits very skilled and purposeful movements 2. Extrapyramidal Tracts- lower, more primitive system, maintain muscle tone, and control body movements ( walking) 3. Cerebellar System- Cerebellum motor coordination, equilibrium, balance, posture. Under the occipital lobe it does not initiate movement but coordinates and smooths it. Figure 21-1. p. 688.

Upper and Lower Motor Neurons Upper motor neurons All descending motor neurons that impact on the lower motor neurons Located in the CNS Convey impulses from motor areas of cerebral cortex to lower motor neurons in the cord Diseases = CVA, Cerebral palsy, Multiple sclerosis Located completely within the CNS= Brain and Spinal cord

Upper and Lower Motor Neurons In the peripheral nervous system 12 cranial nerves 31 pairs of spinal nerves and all branches Final direct contact with the muscles Movement translated into action Reflex arc Examples = cranial nerves, spinal nerves Diseases = spinal cord lesions, poliomyelitis, ALS ALS = amyotrophic lateral sclerosis Reflex Arc – Reflexes maintain balance, muscle tone, and unconscious control and quick reaction to painful or damaging situations. Sensory afferent nerve in muscle is stimulated fibrers carry message to to spinal cord Synapse with motor neuron Motor efferent fibers travel to muscle

Question for Thought Differentiate an upper motor neuron from a lower motor neuron?

Subjective Data In the Interview Any shakes or tremors in the hands or face? Worsen with anxiety, fatigue Relieved with activity, alcohol ADL’s affected Weakness Where? When? Why?

Subjective Data Incoordination Numbness/ Tingling Balance, falling, Legs give out Clumsy Numbness/ Tingling Describe ( pins and needles) Significant past history TIA’s, Atrial Fib.

Assessment of Motor System Body position Involuntary movements Muscle size ( bulk) Muscle tone Muscle strength

Body Position Observe during movement Observe at rest

Involuntary Movements Tremors, tics, fasciculations, myoclonus Note: Location Quality Rate Rhythm Amplitude Normally no involuntary movements. Can they be controlled at will. Tremors- involuntary contraction of opposing muscle groups. Rhythmic back and forth movement of one or more joints. All tremors disappear in sleep. Tics – repetitive twitching of muscle group at inappropriate time –wink, shoulder shrug, head movement Fasciculations – rapid, continuous twitching of resting muscle or part without movement of limb ( can be seen or palpated… eye) Myoclonus- rapid, sudden jerk or short series of jerks at regular intervals…Hiccup, arm or leg jerk when falling asleep

Involuntary Movements Note the involuntary movement in relation to : Posture Activity Fatigue Emotion Other factors

Terms to Describe Movement Flexion Extension Abduction Adduction Pronation Supination

More Terms for Movement Circumduction Inversion Eversion Rotation Protraction

Terms of Movement Continued Retraction Elevation Depression

Muscle Size Compare size and contour Atrophy Unilateral/bilateral Proximal/distal

Muscle Tone A relaxed muscle maintains a slight residual tension referred to as muscle tone. Hypo tonic, Flaccidity. Spasticity. Lead-pipe rigidity.

Muscle Strength Test muscle strength by asking the client to move actively against your resistance or to resist your movement. A muscle is strongest when shortest and weakest when longest. Muscle strength should be equal bilaterally and should fully resist your opposing force

Terms to Describe Strength Weakness (paresis) Paralysis (plegia) Hemiparesis Hemiplegia Paraplegia Quadriplegia Impaired strength = paresis Absence of strength = plegia Hemiparesis = weakness of ½ of the body Hemiplegia = paralysis of ½ of the body Paraplegia = paralysis of the legs Quadriplegia = paralysis of all 4 limbs

Grading Muscle Strength Scale 0-5 0 - no muscular contraction 1 – slight contraction 2 – Full ROM, gravity eliminated

Grading Muscle Strength 3 – Full ROM against gravity 4 – Full ROM against gravity, some resistance 5 – Full ROM against gravity full resistance without evident fatigue = Normal Muscle Strength Normal individuals vary widely in their strength. Remember to take into consideration Age, sex and muscular training. If abnormality in ROM present- measure with a goniometer

Cerebellar Function Balance tests Gait Observe normal walk Tandem Walking ( heel – to- toe ) Romberg Test (stand, feet together, arms at side, close eyes) Shallow knee bend or hop on one leg What findings would you expect to see when assessing gait and balance in an older adult? Remember safety…. Stand close enough to prevent fall. Rising from a sitting position without arm supports or stepping up on a sturdy stool rather than hopping for older patients

Cerebellar Function Coordination and Skilled Movements RAM ( Rapid alternating movements) Pat Knees Thumb to each finger Finger to finger Finger to nose Heel to shin

Question for Thought List and describe 3 tests of cerebellar function?

Charting Sample For Normal Muscle Strength (objective) Able to maintain flexion against resistance and without tenderness For Motor ( objective) No atrophy, weakness or tremors. Gait smooth and coordinated, able to tandem walk, negative Romberg. RAM, finger-to-nose smoothly intact