Motor Speech Set

The CNS consists of

the brain & the spinal cord

The PNS is composed of

12 pairs of cranial nerves & 31 pairs of spinal nerves

The brainstems consists of:

\-midbrain

\-pons

\-medulla

Function of Cerebellum

\-Coordinate voluntary movements

\-Damage results in ataxia

Intention Tremor

\-Only observed during gather performance of voluntary movements; not present at rest

\-Due to lesions of cerebellar hemispheres

Primary Motor Cortex

\-Located on pre central gyrus

\-Receives planned motor impulses from cortical & subcortical areas of the brain

\-Pyramidal system

Basal Ganglia

\-Important in planning & refining of slow, continuous movements

\-When BG are hyper excited due to decreased levels of dopamine, voluntary movements are greatly compressed & attenuated (Parkinson’s Disease)

\-When BG neurons degenerate & lose inhibitory abilities, movements can be exaggerated & purposeless (Huntington’s Disease)

Substantia Nigra

\-Connected to BG; contains a large number of neurons that produce dopamine

\-Lowered levels of dopamine result in muscular rigidity, tremor, gait disturbances & difficulty initiating movement (Parkinson’s Disease)

\-Motor speech disorder associated with Parkinsonism is hypo kinetic dysarthria (tight, restricted movements)

Pyramidal System

\-Responsible for carrying the impulses that control **voluntary, fine motor movements**

\-Works at a __conscious level__

\-Tracts from primary motor cortex, to brainstem or spinal cord

\-Damage results in muscle weakness & rapid fatigue

\-Unilateral damage results in **unilateral upper motor neuron dysarthria;** __a loss of fine motor movement in the articulators__

Corticospinal Tract

\-Descend from the cortex, through the internal capsule, the brainstem & into the spinal cord

\-Most fibers cross at “pyramidal decussation” & continue down the opposite side

Corticobulbar

\-Descend from the cortex but terminate in the brainstem

\-DO NOT cross the midline; bilateral cortical innervation for most cranial nerves

Extrapyramidal System

\-Transmits impulses that control the postural support needed by fine motor movements of the pyramidal system

\-Works more unconsciously & automatically

Upper Motor Neurons

\-Motor fibers within the CNS; includes pyramidal & extrapyramidal pathways

\-Damage results in **spasticity**

\-Motor speech disorder associated with bilateral upper motor neuron damage is **spastic dysarthria** 

Lower Motor Neurons

\-The motor neurons in the cranial and spinal nerves

\-Damage results in **muscle paralysis or paresis**

**-Flaccid dysarthria** is the result of damage to the lower motor neurons in the cranial nerves that innervate muscles of speech production

Flaccid Dysarthria

\-caused by the impairments of the **lower motor neurons** in the cranial or spinal nerves; individuals have a **weakness** in the speech or respiratory musculature and **hypotonia;** the result of damage to the PNS

\-__Characteristics__: slow-labored articulation, hypernasal resonance, hoarse-breathy phonation

Lower Motor Neurons AKA…

**“final common pathway”** because they are the last and only “road” that the neural impulses from the upper motor neurons can travel to reach the muscles 

Damage to CN V can result in….

Bilateral damage resulting in imprecise articulation (can’t bring jaw up to make bilabial & other sounds)

Damage to CN VII can result in….

reduced range of motion

Damage to CN X can result in….

* Pharyngeal Branch
* Damage can affect movement of the velum
* Bilateral damage results in **hypernasality** due to weakness/paralysis of the muscles 
* Also imprecise speech
* External Superior Laryngeal Nerve Branch
* Innervates cricothyroid (which helps to stretch & tense VF during speech)
* Damage = decreased loudness,  increased breathiness, **pitch changes**
* Recurrent Nerve Branch
* Supplies motor innervation to all intrinsic muscles of the larynx except cricothyroid
* The recurrent nerve is a vital contributor to phonation because it supplies the motor innervation for all the adductor and abductor muscles of the vocal folds. 
* Damage = **breathy & hoarse phonation; inhalatory stridor** 

Damage to CN XII can result in….

* Bilateral damage to the hypoglossal nerve will result in overall __weakness of the tongue, reduction in the range of tongue movement, and muscle atrophy on both sides of the tongue.__
* **Damage = imprecise articulation; slow lingual movements** 

Damage to spinal nerves

\-**decreased speech loudness** as a result of __reduced subglottic air pressure.__ -**shortened speech phrasing** because of the __reduced amount of air available for phonation__

\-**breathy or strained vocal quality**

Speech Characteristics of Flaccid Dysarthria (subsystems)

**Laryngeal (Phonation):** hoarse-breathy, reduced pitch & loudness variations, audible inspirations (due to incomplete adduction of the vocal folds- damage to CN X)

\
**Velopharyngeal (Resonation):** hypernasal, nasal air emissions (due to incomplete velopharyngeal closure)

\
**Orofacial (Articulation):** slow-labored, imprecise (ineffective articulation, could be from poor labial muscle control, lingual control)

\
**Prosody:** short phrases (due to wasted air escaping, poor breath support/functional reserve)

\
**Respiration:** reduced pressure generation, shallow inhalations, reduced exhalation control, slow breaths (not enough subglottilc air pressure, limited excursion of the diaphragm)

Speech Musculature Characteristics associated with Lower Motor Neuron (CN) Lesions

\-Weakness

\-Paralysis

\-Hypotonicity

\-Atrophy

\-Hypoactive reflexes

Causes of Flaccid Dysarthria

* Can be caused by *anything that disrupts the flow of motor impulses along the cranial or spinal nerves that innervate the muscles of speech production.*
* Myasthenia Gravis
* Guillian-Barre Syndrome
* Polio
* Physical Trauma
* Brainstem Strokes
* Tumors

Spastic Dysarthria

caused by bilateral damage to upper motor neurons; speech is slow, effortful, and has a harsh vocal quality

\-Increased muscle tone of spasticity but weakness, reduced ROM, slowness in speech musculature

\-\*damage must be bilateral to result in spastic dysarthria!!!

\-usually results in hyperadduction of the VF

Causes of Spastic Dysarthria

**Any injury that causes bilateral damage to the upper motor neurons of the pyramidal and extrapyramidal systems** can lead to spastic dysarthria

\-Brainstem strokes

\-ALS (can also be mixed dysarthria)

\-MS

_Traumatic Head Injury

Speech Characteristics of Spastic Dysarthria (subsystems)

Overall, the speech errors in this dysarthria are the result of spasticity, slowness, and weakness in the vocal-tract muscles

__Articulation:__ **imprecise consonants & vowel distortions**

__Phonation:__

\-**harsh vocal quality** (due to subglottilc air leakage through tense, partially abducted VFs).

\-**strained-strangled vocal quality** (due to hyper adduction of the VFs; subglottilc air being forces through a narrow, tightly constricted larynx)

\-**low pitch** (as a result of increased muscle tone in the larynx)

__Resonance:__ **hypernasality** (cause by spasticity in the velar muscles, reducing range of soft palate movement)

__Prosody:__

\-**mono pitch intonation** (tenseness reduces ability to contract & relax which is needed to vary pitch)

**-monoloudness** (increased tone reduces ability to vary tension of the vocal fold)

**-short phrases** (due to abnormally tight lynx)

**-slow rate of speech**

Speech Musculature Characteristics of Hypokinetic Dysarthria

Substantia Nigra Lesions

\-Hypokinesia

\-Hypertonicity

\-Acceleration of EMG patterns

\-Tremors

Speech Characteristics of Hypokinetic Dysarthria (subsystems)

__Laryngeal (Phonation):__ reduced loudness, harsh-hoarse, monoloudness, monopitch, reduced stress  (horse & breathy caused by incomplete VF closure during phonation - air leaks through)

__Velopharyngeal (Resonation):__ Normal

__Orofacial (Articulation):__ fluctuating, imprecise intelligibility (probably caused by reduced ROM of articulators)

__Prosody:__ slow rate with intermittent rapid-fire bursts, abnormally long pauses & prolongations of syllables (due to akinesia and limited range of motion in the laryngeal musculature)

__Respiration:__ shallow inhalations, reduced exhalation control, rapid breaths, irregular & sudden-forced patterns (due to reduced ROM of respiratory muscles)

Slow vs. Quick Forms of Movement Disorders

Quick:

\-Huntington’s Disease

\-Ballismus

\-Essential/organic voice tremor

\-Myoclonus

\
Slow:

\-athetosis

\-dyskinesias

\-dystonias

Speech Musculature Characteristics of Extrapyramidal Pathways Lesions

\-Hyperkinesis (uncontrollably quick-jerky or slow-twisting movements)

\-Variable tonicity

\-Tremors

\-Variable weakness & paresis

Speech System Characteristics of Hyperkinetic Dysarthria (subsystems)

__Laryngeal (Phonation):__ strained, harsh, tremorous, monoloudness, monopitch

__Velopharyngeal (Resonation):__ Normal

__Orofacial (articulation):__ variable imprecision

__Prosody:__ inappropriate silences, prolongations of sounds & intervals

__Respiration:__ shallow inhalations, reduced exhalations, rapid breaths, antagonistic involuntary muscular contractions, irregular & sudden forced patterns

Ataxic Dysarthria

caused by damage to the cerebellum or to the neural pathways that connect the cerebellum to other parts of the central nervous system (CNS).

Speech System Characteristics of Bilateral Cerebellum Lesion - Ataxic

\-Incoordination

\-Dysrythmia

\-Dysdiadochokinesis

\-Dysmetria

\-Hypotonia

\-Intention tremor

Speech System Characteristics of Ataxic Dysarthria (subsystems)

__Laryngeal:__ Hoarse-breathy, coarse voice, tremor, mono pitch, monoloudness

__Orofacial (articulation):__ imprecise, slow & irregular

__Prosody:__ explosive syllable stress, loudness & pitch outbursts, abnormal prolongations of phonemes & intervals between sounds & words (due to hypotonia which results in slow movement)

__Respiration:__ shallow inhalations, reduced exhalation control, rapid breaths (due to reduced vital capacity), irregular & sudden forced patterns

Velopharyngeal Insufficiency

Nasal vocal quality due to the velum having insufficient closure to the posterior wall of the pharynx → air escaping

\-Glottal stops; hoarse voice; hypernasality