The Functional Anatomy of Phonation

7/28/2019 The Functional Anatomy of Phonation

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ANATOMY OF THE LARYNX

The larynx is located in the anterior aspect of the neck, anterior to the inferior portion of the

pharynx and superior to the trachea.

The larynx consist of 3 large, unpaired cartilages (cricoids, thyroid, epiglottis); 3 pairs of

smaller cartilages (arytenoids, corniculate, cuneiform); and a number of intrinsic muscles.

The hyoid bone, while technically not part of the larynx, provides muscular attachments

from above that aid in laryngeal motion.

CARTILAGES OF THE LARYNX

CRICOID CARTILAGEIts a ring of hyaline cartilage located at the inferior aspect of the larynx and is the

only complete ring of cartilage around the trachea. It has the shape of a signet

ring, with a broad portion posterior to the airway (lamina of cricoids cartilage) and a

narrower portion circling anteriorly (arch of cricoids cartilage). The posterior surface


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of the lamina contains 2oval depressions, which serves as attachment sites for the

posterior cricoarytenoid muscles, separated by a vertical midline ridge that serves as

an attachment to the oesophagus.

THYROID CARTILAGE: largest cartilage in larynx, articulates with cricoids at pairedcricothyroid joints. Inner surface provides anterior point of attachment for vocal

folds. Articulates with hyoid bone with superior cornu. Its formed by the right and

left lamina that is separated posteriorly and joined together at an acute angle in the

anterior midline, forming the laryngeal prominence, commonly known as Adams


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apple.

EPIGLOTTIS: leaf-shaped cartilage; only cartilage not made of hyaline. Made offibro cartilage. Sits medial to hyoid bone and thyroid cartilage. Protective structure

in swallowing covers opening to larynx. It protects the larynx from aspirations of

foods or liquids being swallowed. The depressions on either side of the median fold,

between the root of the tongue and the epiglottis, are called the valleculae

epiglottica.

ARYTENOID CARTILAGES:sit on top of posterior cricoids cartilages. Its the point ofPosterior attachment for vocal folds and vocal ligaments. They are pyramidal in shape

and have 3surfaces, a base and apex.


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CORNICULATE CARTILAGES: sits on top of the arytenoids. The corniculate cartilagesare 2small, club-shaped cartilages that articulate with the apices of the arytenoids

cartilages, serving to extend them posteriorly and medially. They are located in the

aryepiglottic folds of mucous membranes.

CUNEIFORM CARTILAGES: embedded in muscle adjacent to arytenoids. Stiffenersprovide support to the aryepiglottic folds. They are two small, club-shaped cartilages

that lie anterior to the corniculate cartilages in the aryepiglottic folds.


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MUSCLES OF THE LARYNX

INTRINSIC LARYNGEAL MUSCLES


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These smaller muscles, within the structure of the larynx, move the vocal folds in reference

to each other: they abduct, adduct, and alter vocal fold shape; they also change the

longitudinal tension.


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EXTRINSIC LARYNGEAL MUSCLES

These larger muscles, outside the larynx, position and support the larynx; they may move

the cartilages, which in turn, stretch or compress the vocal cords.

LIGAMENTS OF THE LARYNX


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EXTRINSIC LIGAMENTS: the ligaments connecting the thyroid cartilage with the hyoid

bone are the hyothyroid membrane, middle and two lateral hypothyroid ligaments.

Median hyothyroid ligament

THE LATERAL HYOTHYROID LIGAMENT (ligamentum hyothyreoideum laterale; lateralthyrohyoid ligament).

THE INTRINSIC LIGAMENTS

Its beneath the mucus membrane of the larynx is a broad sheet of fibrous tissue containing

many elastic fiber, termed the elastic membrane of the larynx. They include;

CRICOTRACHEAL LIGAMENT


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HYPOEPIGLOTIC LIGAMENT THYROEPIGLOTTIC LIGAMENT

MEMBRANES

Fibro elastic membrane Quadrangular membrane Thyrohyoid membrane Conus elasticus

LARYNGEAL PHYSIOLOGY: HOW IT WORKS

Understanding how the structures of the larynx work is a complicated process as it works

aerodynamically, in response to the breath stream flowing through the glottis. Once you

understand how the stream of air is chopped up to make the waves of sound, its quite

simple to grasp the different ways in which that sound can be modified to change the pitch

(i.e., singing high or low), the intensity (volume) or to switch registers.

HOW VIBRATION HAPPENS

THE BERNOULLI EFFECT


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It is the scientific principle that draws the vocal folds together. The Bernoulli Effect is all

around us. It is the main principle of lift, which causes airplane to fly and baseball to spin.

A simple example of how the Bernoulli Effect works is experienced by a bicycle commuter

everyday: riding along, a large truck passes her. Its speed creates an area of lower pressure,

it draws in d surrounding air as it passes the cyclist, and she feels as if she is being sucked

towards the truck-in fact she is! Another example is found in the tap in a high school science

lab. The flow is constricted in a very narrow nozzle. Above the nozzle is a small hole, which

draws in air to create a vacuum in experiments.

The vocal folds are also drawn in by the Bernoulli Effect. The intrinsic muscles of the larynx

bring the vocal folds together, theyapproximate them, so that the space between the

folds, glottis, is essentially closed off. Once they are closed, the air stream creates a pressure

against the closed vocal folds until they are blown apart. As the air rushes through the very

narrow, constricted opening, it must accelerate to get through. The high speed air much like

the truck in the example above creates suction perpendicular to the direction of its flowit

draws the side of the opening in.

In the Bernoulli Effect, increase in airflow results in air pressure decrease


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Bernoulli Effect is a constant flow of air, at appoint of constriction there will be an increase

in pressure at the constriction, an increase in velocity of flow, and a decrease in air pressure

perpendicular to the flow.

THE WAVE

This is the simultaneous actions of the vocal folds and the mucosal wave.

PITCH CHANGE

Fundamental frequency: when speaking or singing there is always an underlying noteto each sound.

INTENSITY CHANGE

Intensity is the size of the wave which controls volume.

MODES OF VIBRATION

regular or modal (chest- tone) falsetto (head-tone) glottal fry registers refers to the type of voice especially in singing attacks

HOW PHONATION OCCURS

Voice is produced by the following mechanism (aerodynamic myoelastictheory of voice production);


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Vocal cords are kept adducted Infraglottic air pressure is generated by the exhaled air from the lungs due to

contraction of thoracic and abdominal muscles

The air force open the cords and is released as small puffs which vibrates thevocal cords to produce sound which is amplified by the mouth, pharynx, nose

and chest

The sound is converted into speech by the modulary action off the lips,tongue, palate, pharynx and teeth

Intensity of the sound depends on the air pressure produced by the lungswhile pitch depends on the frequency with which the vocal cords vibrate

VOICE DISORDERS

These are medical conditions preventing the production of speech. This includes;

Corditis Vocal fold nodules Vocal fold cysts Vocal cord paresis Reinkes oedema Spasmodic dysphonia Foreign accent syndrome Bogart-Bacall syndrome Laryngeal pappilomastosis


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Puberphonia Laryngitis Diplophonia breathiness

FUNCTIONS OF LARYNX

Protection of lower airways

Phonation

Respiration

Fixation of the chest


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REFERENCE

1. Titze, I.R (1994). Principles of voice production2. Lieberman, Philip; Sheila Blumstein (1988). Speech physiology, speech perception

and acoustic phonetics

3. Greene, Margaret; Lesley Matheson (2001). The voice and its disorders. John Wileyand sons; 6

thedition.

4. Zemlin, Willard (1998). Speech and hearing science: anatomy and physiology. Allynand bacon; 4

thedition

5. Titze, I.R (2006). The myoelastic aerodynamic theory of phonation6. McKinney, James (1994). The diagnosis and correction of vocal faults

The Functional Anatomy of Phonation

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