NeuroExam: Motor System, Somatosensory, Coordination

Motor

what are the goals in conducting a motor function exam?

• examine gross appearance of muscle

  • muscle tone & strength

where are upper motor neurons located & what neurotransmitter do they use?

originate in motor cortex or brain

glutamate

where are lower motor neurons located, what do they supply & what neurotransmitter do they use?

• originate in spinal cord or brainstem

• innervate muscles or glands

• use acetylcholine

what can upper motor neuron lesions lead to?

• weakness

• spasticity (rickety arm)

• hyperreflexia

• retained primitive reflexes

  • ex: grasp, suck, snout

what can lower motor neuron lesions lead to?

• weakness

• hypotonia (low tone)

• hyporeflexia

• atrophy

• fasciculations

Somatosensory

what is examined when looking at somatosensory function?

• temperature

• pain

• vibration

• proprioception

how is touch examined?

• close eyes

• draw letters/numbers in hand

how might dysfunction show up on this test?

• astereogenosis

• agreaphesthesia

what is astereognosis?

inability to recognize objects by touch

what is agraphesthesia?

inability to recognize letters/numbers by touch

what does this tell us about brain health?

points to sensory cortex of parietal lobe

Coordination

what are the kinds of dysfunction in coordination?

• dysdiadochokinesia

• dysmetria

• pronator drift

how does dysfunction look in those w/ dysdiadochokinesia?

• unable to do quick, alternating movements

  • ex: flip hand on surface

what does dysdiadochokinesia tell us about brain health?

• signals MS in adults

• cerebellar tumours in kids

how does dysfunction look in those w/ dysmetria?

impairment performing accurate movements:

• point-to-point movement

• heel-to-shin test

what does dysmetria tell us about brain health (point-to-point movement)?

points to cerebellar damage

what does dysmetria tell us about brain health (heel-to-shin test)?

likely cerebellar => ipsilateral or bilateral

what is examined when looking at coordination?

• standing/sitting

• gait (natural, heel-to-toe)

what might dysfunction look like?

• asymmetries

• poor timing

• width of steps

  • especially when turning & stopping

what may abnormalities point to?

• ethanol inebriation

• cerebellum

what is romberg’s test?

balance w/ eyes open vs closed => points to cerebellar damage

what is pronator drift?

rotation & vertical motion of arm

what does damage point to?

points to damage to the pyramidal tract