Motor Speech Disorders
Lecture Notes
Definition Measurements Examples
Impairment Any loss or abnormality of psychological, physiological or anatomical structure or function Often instrumental muscle weakness 

loss of hair cells 

missing limb

Disability Any restriction or lack of ability (resulting from an impairment) to perform an activity in the manner or within the range considered normal Often perceptual articulatory imprecision 

reduced hearing sensitivity 

reduced speed of ambulation

Handicap A disadvantage for a given individual (resulting from an impairment or disability) that limits or prevents the fulfillment of a role that is normal Always perceptual, often self-report unable to work at chosen profession 

no effect on lifestyle 

must allow additional travel time

Level Definition Methods Examples Features
Perceptual Characterized by perceptual judgments unmediated by significant instrumentation Auditory perception 

Visual perception 

Tactile perception

slurred speech 


slow rate

most commonly used 

may be best indicator of disability

Acoustic Analysis of the acoustic energy of a speech sample speech spectogram 


computerized speech analyzers

fundamental frequency, voice onset time, format transitions *particularly useful for analyses of phonatory features 

*may be more sensitive to subtle variations in the acoustic signal than are perceptual judgments 

* becoming more common in the clinical setting

Kinematic Analysis of the movements of the articulators strain gauges 


displacement, velocity, acceleration, interarticulator timing *particularly useful in the examination of upper articulators 

*measures primarily at the level of impairment, but can also provide information about disability

Physiologic Instrumental measurements of physiologic characteristics (other than kinematic) EMG 





muscle activity 

vital capacity 

blood flow

*almost always at level of impairment
It is not possible to perfectly predict from one level to another. While prolonged segment durations in an acoustic signal may be related to prolonged movement times, it is not necessarily so. Individuals with reduced articulatory displacements and velocities may have perceptually normal speech, and normal EMG patterns. Each level of description can be useful.

Cranial Nerves:(Webster, p.104; Luschei, p. 69-70)
Cranial Nerve Type Nucleus/Central connections Function
I. Olfactory S olfactory bulb Smell
II. Optic S Lateral geniculate body Vision
III. Oculomotor M Oculomotor Eye movements; extraocular muscles except superior oblique and lateral rectus 

Striated muscle of eyelid 

Autonomic fibers for pupillary constriction and accommodation of lens for near vision

IV. Trochlear M Trochlear Eye movements; superior oblique muscle (rotates eyeball down and out)
V. Trigeminal


Trigeminal (descending and mesencephalic nuclei) 

Masticator Nucleus

Cutaneous and proprioceptive sensation for skin, muscles & joints in face and mouth, sensory for teeth 

Muscles of mastication

VI. Abducens M Abducens Eye movements; lateral rectus (abducts eyeball)
VII. Facial


Tractus solitarius 


Taste for anterior 2/3 tongue, soft palate 

Muscles of facial expression

VIII. Auditory (Vestibulocochlear) S Vestibular and Medial geniculate Audition, equilibrium, postural reflexes, orientation of head in space
IX. Glossopharyngeal


Tractus solitarus 

Nucleus ambiguus

Posterior 1/3 of tongue, tonsil, pharynx, middle ear, 

Autonomic for salivation 

Stylopharyngeus, pharyngeal musculature

X. Vagus


Nucleus solitarus 

Nucleus ambiguus

Caudal pharynx, larynx, thorax, abdomen, taste from epiglottis 

Autonomic for smooth muscle (heart, blood vessels, trachea, bronchi, esophagus, stomach, intestines) 

Striated muscle in larynx, and part of pharynx

XI. Spinal Accessory M Nucleus ambiguus Neck muscles
XII. Hypoglossal M Hypoglossal nucleus Intrinsic tongue muscles