_____________ or nerve cell bodies lie in the motor strip of the cerebral cortex and in several brainstem nuclei

_____________ have cell bodies in the spinal cord termed anterior horn cells

3 Principal Motor Pathways

Name: Supranuclear paralysis

Muscle affected: groups of muscle

Atrophy: slight due to disuse

Tone: spasticity

Reflex: hyperactive tendon reflexes & extensor plantar reflex

Fasciculation: Absent

Nerve conduction: Normal

Name: Nuclear-infranuclear paralysis

Muscle affected: individual muscle

Atrophy: pronounced

Tone: flaccidity & atonia

Reflex: loss of tendon reflex; normal plantar reflex

Fasciculation: Present

Nerve conduction: Abnormal (presence of denervation potentials in EMG)

Sign

Weakness: yes

Reflexes: increased

Atrophy: no

Tone: spasticity

Fasciculation: absent

Sign

Weakness: no

Reflexes: decreased

Atrophy: yes

Tone: flaccidity

Fasciculation: present

Motor Pathways

- Mediate voluntary movement and integrate skilled, complicated or delicate movements by stimulating selected muscular actions and inhibiting others

- Carry impulses that inhibit muscle tone

Motor pathways

- Originate in the motor cortex of the brain

→ Motor fibers travel down into the medulla where they form an anatomical structure resembling a pyramid

→ There the fibers decussate, continue downwards then synapse with the anterior horn cells (or intermediate neurons)

→ Tracts synapsing with motor nuclei of the CNs are called corticobulbar

Motor pathways (clinical correlation)

- When damaged, its functions are reduced or lost below the level of injury.

- Affected limb becomes weak or paralyzed and skilled, complicated or delicate movements are poorly performed when compared with gross motor movements

Motor pathways (clinical correlation)

In the corticospinal tract, when upper motor neurons are damaged above the level of the medullary pyramids motor impairment develops on the _________

Motor pathways (clinical correlation)

In the corticospinal tract, when there is damage below the level of the pyramids, motor impairment develops on the _________

Motor pathways

- Exceedingly complex system that includes motor pathways between cerebral cortex, basal ganglia, brainstem and spinal cord

- Helps to maintain muscle tone and control body movements, especially gross automatic movements such as walking

Motor pathways (clinical correlation)

- Disease does not cause paralysis but can be disabling. - - Damage to this system can cause:

→ Changes in muscle tone (usually increased)

→ Disturbances in posture and gait

→ Slowness or lack of spontaneous and automatic movements

→ Various involuntary movements

Motor pathways

Receives both sensory and motor input and coordinates motor activity, maintains equilibrium and helps control posture

Motor pathways (clinical correlation)

Damage to this system impairs coordination, gait and equilibrium and decreases muscle tone.

Guidelines in Motor Exam

If the problem is in the ____, is the cerebral cortex, basal ganglia, brainstem, cerebellum, or spinal cord responsible?

- E.g., Praxis – loss of learned activity

- E.g., Cerebellar lesion – problem in coordination

Guidelines in Motor Exam

If the problem is in the ____, are motor or sensory nerves primarily affected, or is a lesion in the neuromuscular junction or muscle more likely?

- E.g., Radiculopathy – painful; tuwing “naiipit” ‘yung nerve

- E.g., Carpal Tunnel – median nerve weakness

- E.g., Wrist drop – radial nerve lesion

Motor inspection: Muscle bulk

Muscle groups should appear _________ developed when compared with their counterparts on the other side of the body

Motor inspection: Muscle bulk

A broken leg that has recently been liberated from a cast

will appear ________

Motor inspection: Muscle bulk

In inspecting for atrophy, check the hands, shoulders, thighs, and legs. The spaces between metacarpals, where dorsal interossei muscles lie, should be full or only slightly depressed.

Motor inspection: Muscle bulk

The thenar and hypothenar eminences of the hand should be full and CONCAVE

Motor inspection: Muscle bulk

Furrowing between metacarpals and flattening of the thenar and hypothenar eminences (also seen in median and ulnar nerve damage, respectively) suggest ________

Motor inspection: Muscle bulk

ATROPHY of the hand muscles occurs in NORMAL AGIING

_______ is an increase in bulk with normal or increased strength

___________ is increased bulk with diminished strength

→ E.g., Seen in Duchenne muscle dystrophy

Motor inspection: Muscle bulk

Inspect also for fasciculations in atrophic muscles

→ If absent, tap on muscles with a reflex hammer, which

stimulates them

→ Fasciculations with atrophy and muscle weakness suggest _________

Motor inspection: Involuntary movements

- Rhythmic oscillatory movements of a body part resulting from contraction of opposing muscle groups

- Most common movement disorder

Motor inspection: Involuntary movements

WHAT TYPE OF TREMOR IS THIS?

- Most prominent at rest

- May decrease or disappear with voluntary movement

- E.g. tremors of Parkinsonianism

Motor inspection: Involuntary movements

WHAT TYPE OF TREMOR IS THIS?

- Appear when the affected part is actively maintaining a

posture

- May worsen somewhat with intention

- E.g., Fine rapid tremor of hyperthyroidism

- E.g., Tremors of anxiety, fatigue

- Benign essential (sometimes familial) tremor: persists

throughout movement and not associated with neurological findings

Motor inspection: Involuntary movements

WHAT TYPE OF TREMOR IS THIS?

- Appear with activity and often get worse as the target gets closer

- Absent at rest

- E.g., Cerebellar disorders such as multiple sclerosis

Motor inspection: Involuntary movements

NOT visible to the naked eye except possibly those in the tongue

Motor inspection: Involuntary movements

- Seen under the skin as quivering of the muscle

- Typically benign: particularly when they occur in the calf

- If widespread: may be associated with neuromuscular disease

→ E.g., Amyotrophic Lateral Sclerosis

Motor inspection: Involuntary movements

- Result in the death of LMNs and subsequent muscle denervation

- Causes twitching of fibers seen on gross inspection of affected muscles

Motor inspection: Involuntary movements

- Elicited by having the patient extend both arms with wrists dorsiflexed, palms facing forward, and eyes closed

- (+) Sign: Brief jerky downward movements of the wrist

- Commonly seen with metabolic encephalopathies

- Tested for patients with Liver disease (due to alcoholism)

Motor inspection: Involuntary movements

- Involuntary contractions of single muscles or groups of muscles that result in stereotyped movements

→ E.g., Repetitive winking, grimacing, shoulder shrugging

- Seen in Gilles de la Tourette syndrome

- Also seen as late effects of drugs such as phenothiazines

Motor inspection: Involuntary movements

- Muscle jerk; brief generalized body jerk (<0.25s)

- Sometimes asymmetric

- Occur alone or in association with various primarily generalized epilepsies

Motor inspection: Involuntary movements

- Muscle contractions that are more prolonged than myoclonus and result in spasms

- E.g., Blepharospasm, spasmodic torticollis, oromandibular dystonia, spasmodic dysphonia, and writer’s cramp, spasmodic torticollis

- Can be atonia (loss of tone), weakness, or muscle contraction

- Grotesque, twisted postures

Motor inspection: Involuntary movements

- Movements are slower and more twisting and writhing than and have a larger amplitude

- Most commonly involve the face and distal extremities

- Associated with spasticity

- E.g., Cerebral Palsy

Motor inspection: Involuntary movements

- "Dance"

- Quasi-purposeful movements affect multiple joints with a distal preponderance

- Brief, rapid, jerky, irregular and unpredictable

- Occur at rest or interrupt normal coordinated movements

Motor inspection: Involuntary movements

- Unlike tics, they seldom repeat themselves

- Face, head, lower arms, and hands are often involved

- E.g., Sydenham _______ (with rheumatic fever) and Huntington disease

Motor inspection: Involuntary movements

- Violent flinging movement of half of the body

- Associated with lesions of subthalamic nucleus (body of Louis)

Motor inspection: Involuntary movements

- Loss of consciousness: wakes up confused and unaware

- Result in orofacial or appendicular automatisms (i.e. get stuck doing the same activities/motion), repeated eye blinks, or tonic or clonic motor activity

Motor inspection: Involuntary movements

Arrhythmic, repetitive bizarre movements that chiefly involve the face, mouth, jaw, and tongue

→ Grimacing

→ Pursing of the lips

→ Protrusions of the tongue

→ Opening and closing of the mouth

→ Deviations of the jaw

Motor inspection: Involuntary movements

- Limbs and trunk less involved

- Movements may be a late complication of psychotropic drugs such as phenothiazines, termed as Tardive (late dyskinesias)

- Also occur in long standing psychoses, in some elderly individuals, and in some edentulous persons

Motor inspection: Summary

INVOLUNTARY MOVEMENTS & ABNORMAL POSITIONS

• In the calf: benign / normal

• Widespread: Neuromuscular disease, amyotrophic lateral sclerosis

Motor inspection: Summary

INVOLUNTARY MOVEMENTS & ABNORMAL POSITIONS

• Parkinsonian

• Metabolic

• Cerebellar

• Essential Rubral

• Physiologic tremor

• Tremor of Hepatic encephalopathy

Motor inspection: Summary

INVOLUNTARY MOVEMENTS & ABNORMAL POSITIONS

• Chorea

• Tardive dyskinesia

• Athetosis

• Pseudoathetosis

• Choreoathetosis

• Ballism

Motor inspection: Summary

INVOLUNTARY MOVEMENTS & ABNORMAL POSITION

• Muscle cramps

• Oculogyric crisis

• Hemifacial cramps

• Palatal myoclonus or nystagmus

• Blepharospasm

• Hiccup