Exam 2: Phonation II Flashcards
Interarytenoid Muscles
- Adductors
- located on the posterior surfaces of the arytenoid cartilages
- Described as oblique and transverse arytenoid muscles
Oblique arytenoid muscle characteristics
- more superficial
- looks like an X
- a few muscle fibers continue around the apex of the arytenoid cartilage laterally, angle upward and forward, and insert into the lateral borders of the epiglottis as the aryepiglottic muscle
Oblique Arytenoid: Origin & Insertion, function
Origin: posterior surface of the muscular process and adjacent posterlateral surface of one aryenoid cartilage
Insertion: near the apex of the opposite cartilage
Function: approximate the arytenoid cartilages and are therefore regulators of medial compression
Transverse Arytenoid Muscle: Origin & Insertion, function
Origin: from the lateral margin and posterior surface of one arytenoid cartilage, course in a horizontal direction
Insertion: lateral margin and posterior surface of the opposite arytenoid cartilage
Function: contraction approximates the arytenoid cartilage by causing them to slide along the long axis toward the midline
Cricothyroid Muscle characteristics
- tensor
- actively tense or elongate the VF
- only other tensor (than thyroarytenoid muscle)
- fan-shaped
oblique fibers– pars oblique
anterior fibers– pars recta
Cricothyroid Muscle: Origin & Insertion
Origin: anterolateral arch of the cricoid cartilage
diverges and
Insertion: the thyroid cartilage as two distinct parts
Pars Oblique
lower fibers course upward and back to inset into the anterior margin of the inferior horn of the thyroid cartilage
Pars Recta
upper or anterior fibers course nearly vertical upward to insert along the inner aspect of the lower margin of the thyroid
2 parts of the arytenoid muscle
oblique and transverse
5 distinct layers of the VF
- Epithelium (cover)
- superficial layer of the lamina propria (cover)
- Intermediate layer of the lamina propria (transition)
- Deep layer of the lamina propria (transition)
- vocalis muscle (body)
Epithelium of VF
made of: squamous epithelium
- thin and stiff capsule
- maintains shape of the vocal fold (like a capsule would)
- helps regulate VF hydration
Superficial layer of the lamina propria
- Reinke’s space
- consists of loose fibrous components and elastic components in a matrix
- mass of soft gelatin
Intermediate layer of the lamina propria
made of: elastic fibers
- likened to a bundle of soft rubber-bands
- composed mostly of elastic fibers
Deep layer of VF
made of: collagenous fibers
- like a bundle of cotton threads
- made up of collagenous fibers, contributes to durability of VF
Vocalis Muscle in VF
- has both passive and active mechanical properties
- constitutes the main body of the VF
- passively, is like a bundle of stiff rubberbands
- it is a muscle, so it is active (contractile properties, help control stiffness)
Thyroarytenoid Muslce (TA)
- main mass of the VF
- vocalis muscle (medial bundle) flanks the vocal ligament
- thyromuscularis (lateral bundle) serves as the “body” of the muscle
Vocal Fold’s 3 sections
- the cover (epithelium and superficial layer of lamina propria), aslo called mucosa
- transition (intermediate and deep layers of lamina propria; this is the vocal ligament
- Body (vocalis muscle)
Physiology of VF (Thyroarytenoid)
- the mechanical properties of the outer four layers are controlled passively
- mechanical properties of the body are regulated both passively and actively
- during phonation, a wave traveling on the laryngeal mucosa from its inferior to superior surface can be seen during each cycle of vocal fold vibration, except when the vocal fold is very tense (ex: falsetto)
Mucosal Wave
- soft & pliant superficial layer of the lamina propria is essential for the mucosal wave
- this wave continues across the upper surface of the vocal fold, dissipates before it arrives at the boundary of the thyroid cartilage
Principle function of TA muscle
- regulator of longitudinal tension
- acting unopposed by intrinsic muscle, relaxes VF
- assists in closing glottis by pulling forward on the muscular process
- when contraction of TA is opposed by intrinsic muscle, the result is an increase in VF tension, then can act as adductor, a tensor or a relaxer of VF
Pre-phonation phase
period during which the VF move from an abducted to either an adducted or partially adducted position
quiet breathing prior to phonation
vocal fold approximation
subglottal pressure builds up beneath the vocal folds
the velocity of air as it flows through the glottal contrition is raised sharply
Medial Compression
the extent to which the VF are approximated, this is brought about by the action of the adductor muscle
- brought about by adductor muscles
- muscles work in pairs…contraction of one results in contraction of companion muscles
- direct relationship between the extend of medial compression and the magnitude of air pressure required to force the VF apart and initiate phonation
Bernoulli Effect
aerodynamic law
-if the volume flow is constant, velocity of flow must increase at an area of constriction, but with a corresponding decrease of pressure at the constriction
- assume the VF are nearly approximated
- air stream released by exhalation
- velocity will be constant until glottal contraction
- velocity will increase as air passes “chink”
- results in negative pressure between the medial edges of the VF
- VF literally sucked toward one another
Initiation of Phonation
- as the glottal area reaches critical value, the VF start to vibrate (before approximation)
- initial movement results in a decrease in the glottal area
- VF undergo many vibrations before thy meet and obstruct the air stream
- if subglottal pressure is adequate, medial compression of VF will be overcome and they will be blown apart to release a puff of air into supraglottal area
- explosive
- immediate short term decrease in subglottal pressure
Elastic Tissue + Bernoulli Effect =
Vocal Folds snap back again to midline
Simultaneous attack
there is a healthy balance between the respiratory and laryngeal mechanism
air stream released just as the vocal folds meet at the midline
“zero”…occurs with voiced sounds
Breathy attack
air stream is released before the VF adduction is completed
-considerable amount of air may be exhaled while folds are being set into periodic vibration
“hairy”…occurs throughout long production strings of words
Glottal attack
when phonation is initiated while the vocal folds are subjected to considerable medial compression
- voice exhibits an onset more than during either simultaneous or breathy attacks
- vocal tone is explosive in nature
- the initiation is called a glottal attack
“okay”…used when words begin with a stressed vowel
Attack Phase
begins with the vocal folds adducted, or nearly adducted, extends through the initial vibratory cycles
- highly variable in duration
- complete obstruction of airway passageway is not necessary to initiate phonation
- initial movement in incompletely adducted vocal folds is medial
Characteristics of a Vibratory Cycle
- rate of vibration
- open vs closed phase
- periodicity
- symmetry
Rate of vibration
- described as frequency (Hz) or cycle per second
- very fast
- cant’ see with blind eye
- larynx operates most efficiently at the frequency of vibration that correlates closely with habitual pitch
women: 225 Hz
kids: 295 (really young)
Open vs Closed phase
- VF begin to open first posteriorly
- Glottal chick moving anteriorly
- Closure begins with the entire medial edge of the folds moving toward the midline
- posterior portion is the last to close
Conversational Pitch & Intensity
VF vibrate almost in their entirety, vibration is wavelike for the main mass of VF, along horizontal plane, slight vertical displacement that increases with loudness
Open Phase
- VF begins to be forced open from beneath
- upward progression of the opening in an undulating fashion
- lower edges of VF are the first and the upper edges are last to be blown apart
Closed phase
the lower edges lead the upper edges (wave-like)
Periodicity
- with mass, length, tenstion, and subglottal pressure held constant, vocal fold vibrations will recur with moderately precise regularity
- regularity of successive cycle of vibration
Symmetry
- VF will open and close as a mirror image of one another
- open and close in synchrony
Pitch Nomenclature
- Fundamental frequency
- pitch level
- pitch ranges
- natural level
- optimum pitch level
Male vs Female VF length
Males: 15-20mm
Females: 9-13mm
In abducted position, VF are…
near maximum length
length of VF at various positions never exceeds…
the length of the vocal folds in their abducted postion
Increase in length of vocal chords will…
increase pitch
Modifications in length and tention are mediated through…
cricothyroid, thyroarytenoid, and posterior cricoarytenoid
Mass in Pitch Changing Mechanism
- high pitch phonation: VF thickness is never reduced to below 1/2 of what it is during lowest pitch phonation
- increase in tension in the vocal folds is the sole agent responsible for pitch increases
- accompanying length and thickness changes is imply the result of the elastic tissue of the vocal folds yielding to the marked increase in tension
