Anatomy & Physiology of the Phonatory System

Vocabulary flashcards reviewing the anatomical structures, intrinsic and extrinsic muscles, laryngeal valves, tissue layers, and physiological principles of phonation based on the lecture notes.

Phonation

The process of the vocal folds coming together to vibrate for the production of sound, resulting from a combination of airflow and laryngeal muscle activation.

Larynx

serving as the principal structure of phonation .A musculocartilaginous structure located anteriorly in the neck in front of vertebrae $\text{C4}\text{--}\text{C6}$, sitting atop the trachea and below the hyoid bone,

Thoracic Fixation

A biological function of the larynx where complete vocal fold closure traps air within the lungs to create a solid rigid framework in the torso to assist in heavy lifting and physical exertion.

Hyoid Bone

A U-shaped structure situated at the union of the tongue and larynx that serves as the attachment point for $30$ muscles, unique because it does not articulate directly with any other bone.

Thyroid Cartilage

The largest hyaline cartilage of the larynx, composed of two thyroid laminae that fuse anteriorly at the thyroid angle and notch (Adam's Apple) and features superior and inferior cornua and an oblique line.

Cricoid Cartilage

A signet ring-shaped hyaline cartilage that is narrow in front and taller in back, sitting atop the trachea and below the thyroid cartilage.

Epiglottis

A leaf-like elastic cartilage structure located behind the hyoid bone at the root of the tongue that reflexively folds backward over the trachea during swallowing to protect the airway. Makes sure food doesn’t get into the airway

Arytenoid Cartilages

Small, paired, pyramidal hyaline cartilages sitting atop the posterior cricoid cartilage, featuring a lateral muscular process for adductor/abductor muscle attachments and an anterior vocal process for vocal fold attachment.

Corniculate Cartilages

Small, paired, horn-shaped elastic cartilages mounted on the apices of the arytenoid cartilages that have no active speech function and are considered vestigial. Previously had a function but not anymore due to evolution.

Cuneiform Cartilages

Small, paired, wedge-shaped elastic cartilages embedded within the aryepiglottic folds to provide structural stiffness and support to the folds.

Cricoarytenoid Joint

The laryngeal joint between the cricoid cartilage and each arytenoid cartilage that allows rocking, rotation, and sliding movements to abduct and adduct the vocal folds.

Cricothyroid Joint

The laryngeal joint between the inferior cornua of the thyroid cartilage and the lateral surface of the cricoid cartilage that acts as a pivot point to lengthen or shorten the vocal folds to control voice pitch. Very important for pitch

Aryepiglottic Folds

Tissue folds composed of muscle and connective tissue run from the lateral epiglottis to each arytenoid apex, forming the superior borders of the quadrangular membrane to assist in sealing the airway during swallowing.

Ventricular Folds (False Vocal Folds)

Thick folds of mucous membrane and tissue positioned superior to the true vocal folds containing mucous glands that lubricate the true vocal folds.

Laryngeal Ventricle

The cavity or pocket located between the false vocal folds superiorly and the true vocal folds inferiorly, lined with mucous glands for vocal fold lubrication.

Epithelium

The outermost, thin layer of tissue wrapping the vocal folds that protects the deeper tissue layers from mechanical abrasion and damage.

Lamina Propria

The intermediate connective tissue matrix of the vocal folds divided into three layers: superficial (elastin fibers), intermediate (elastin and collagen), and deep (collagen fibers).

Layers of the Vocal Fold

The five distinct tissue layers comprising the vocal folds: 1) Squamous epithelium, 2) Superficial lamina propria, 3) Intermediate lamina propria, 4) Deep lamina propria, and 5) Thyroarytenoid muscle.

Cover-Body Model

A structural classification of the vocal fold layers consisting of the Cover (epithelium & superficial lamina propria), Transition/Vocal Ligament (intermediate & deep lamina propria), and Body (thyroarytenoid muscle).

Glottis

The opening or space between the true vocal folds, dividing the laryngeal cavity into supraglottal and subglottal regions.

Valleculae

Small depression pockets located between the base of the tongue and the anterior epiglottis where swallowed material can pool in individuals with dysphagia.

Extrinsic Laryngeal Muscles

A group of paired neck muscles with one attachment to a laryngeal structure or hyoid bone and one non-laryngeal attachment, categorized as elevators (suprahyoids) or depressors (infrahyoids).

Laryngeal Depressors (Infrahyoids)

Extrinsic neck muscles situated below the hyoid bone—including the Sternohyoid, Sternothyroid, Omohyoid, and Thyrohyoid—that pull down on the hyoid bone and larynx.

Laryngeal Elevators (Suprahyoids)

Extrinsic neck muscles situated above the hyoid bone—including the Digastric (anterior/posterior), Stylohyoid, Mylohyoid, and Geniohyoid—that pull up on the hyoid bone and larynx.

Posterior Cricoarytenoid Muscle (PCA)

The sole intrinsic laryngeal muscle responsible for vocal fold abduction, originating on the posterior cricoid and inserting onto the muscular process of the arytenoid to open the glottis ("the safety muscle").

Lateral Cricoarytenoid Muscle (LCA)

An intrinsic laryngeal adductor muscle originating on the anterolateral cricoid cartilage and inserting into the muscular process of the arytenoid to pull the vocal process inward.

Transverse Interarytenoid Muscle

An intrinsic laryngeal adductor muscle formed as an unpaired horizontal band spanning between the posterior surfaces of both arytenoid cartilages.

Oblique Interarytenoid Muscle

Paired intrinsic adductor muscles crossing in an X-shape between the posterior base of one arytenoid process to the apex of the opposite arytenoid to pull the apices together.

Cricothyroid Muscle

An intrinsic tensor muscle comprised of the Pars recta and Pars oblique that pulls the thyroid cartilage down and forward relative to the cricoid, stretching and tensing the vocal folds to raise pitch.

Thyrovocalis Muscle

The medial division of the thyroarytenoid muscle originating from the internal thyroid notch and inserting into the vocal process of the arytenoid, acting as a vocal fold tensor.

Thyromuscularis Muscle

The lateral division of the thyroarytenoid muscle originating from the thyroid notch and inserting into the muscular process of the arytenoid, acting to shorten and relax the vocal folds.

Myoelastic-Aerodynamic Theory

The primary model of phonation stating that vocal fold vibration is driven by an interplay of muscle contraction, tissue elasticity/recoil, and subglottal aerodynamic forces.

Medial Compression

The force with which the vocal folds are adducted and held together at the midline, requiring higher subglottal pressure to blow them apart and creating greater acoustic amplitude.

Bernoulli Effect

An aerodynamic principle stating that as fluid or air velocity increases through a point of constriction, internal fluid pressure decreases perpendicular to the flow, drawing the walls of the constriction (vocal folds) together.

Simultaneous Attack

A phonatory initiation mode where exhalation and adduction of the vocal folds occur at the exact same moment.

Breathy Attack

A phonatory initiation mode where exhalation begins prior to complete adduction of the vocal folds.

Glottal Attack

A phonatory initiation mode where complete adduction of the vocal folds precedes the release of exhalation air pressure.

Mucosal Wave

The continuous traveling wave motion of the vocal fold cover as it opens and closes rhythmically from inferior to superior.

Fundamental Frequency ($F_0$)

The rate at which the vocal folds complete full vibration cycles per second, measured in Hertz ($\text{Hz}$), averaging roughly $110\,\text{Hz}$ for adult men, $220\,\text{Hz}$ for adult women, and over $300\,\text{Hz}$ for children.

Modal Register

The primary register of phonation used in routine conversational speech, characterized by complete inferior-to-superior mucosal wave movement.

Glottal Fry (Pulse Register)

A low-frequency register ($30\text{--}90\,\text{Hz}$) characterized by low subglottal air pressure ($\approx 2\,\text{cm H}_2\text{O}$), reduced vocal fold tension, and a thick, irregular vibratory pattern ("creaky voice").

Falsetto Register

The highest register of phonation ($>1000\,\text{Hz}$) produced with elongated, thin, highly tensed vocal folds that briefly make contact during each cycle.

Optimal Pitch

The most anatomically and physiologically efficient fundamental frequency for an individual's vocal folds, averaging around $212\,\text{Hz}$ for adult females and $132\,\text{Hz}$ for adult males.

Habitual Pitch

The average fundamental frequency routinely used by a person during continuous speech, which ideally matches their optimal pitch.

Pitch Range

The span between the lowest and highest fundamental frequencies achievable by an individual, typically spanning at least two octaves in healthy voices.

Intonation

Changes and patterns in pitch across an entire sentence or utterance that convey grammatical information or speaker intent.

Vocal Stress

Pitch and intensity changes applied at the syllable or word level to emphasize specific information or modify word meaning.

Biological function of larynx

Prevents air escaping the lungs when closed (“holding breath”) • Prevents foreign substances from entering the larynx • Forcefully expels foreign substances • Aids in lifting – thoracic fixation for solid framework with which to work

OVERLAID FUNCTION OF THE LARYNX

Phonation for speech is an overlaid (non- biological) function • generates sound only when not fulfilling vital biological functions • can produce sound that varies widely in pitch and loudness

The larynx is comprised of

• three paired cartilages • three unpaired cartilages • ligaments • Membranes • mucous membrane lining

CARTILAGES OF THE LARYNX

Thyroid (hyaline) • Cricoid (hyaline) • Epiglottis (elastic) • Arytenoid (2) (hyaline) • Corniculate (2) (elastic) • Cuneiform (2) (elastic)

VALVES OF THE LARYNX

Aryepiglottic folds • False (ventricular) folds • Laryngeal ventricle • True Vocal folds

supraglottal

• Above glottis:Ventricle of larynx • Ventricular folds

subglottal

Below glottis
• From vocal folds to bottom of cricoid

LARYNGEAL ROLE IN RESPIRATION

• Vocal fold abduction increased for forced inhalation, decreased for quiet inspiration

Hyoepiglottic Ligament

Connects the hyoid bone with the anterior surface of the epiglottis

• Thyroepiglottic Ligament

• Attaches the epiglottis to the thyroid cartilage below the thyroid notch

• Gloss-epiglottic Ligament

• Attach the epiglottis to the tongue

LARYNGEAL DEPRESSORS
INFRAHYOIDS

Sternohyoid • Sternothyroid • Omohyoid • Thyrohyoid

VOCAL FOLD ADDUCTORS

Lateral cricoarytenoid (LCA) • Main adductor • Interarytenoid (IA) • Transverse interarytenoid • Oblique interarytenoid

INTERARYTENOID MUSCLES

tWO bundles of muscle fibers • Contraction adducts the vocal folds, closes the glottis Two parts: • Transverse Interarytenoid • Oblique Interaryteno

OBLIQUE INTERARYTENOID MUSCLES

Function: pull the apex of arytenoid cartilages medially for adduction

VOCAL FOLD TENSORS

• Cricothyroid muscles – two muscle bundles • Pars recta • Pars oblique • Thyroarytenoid • Thyrovocalis • Thyromuscularis

THYROARYTENOID MUSCLES

• Medial: thyrovocalis muscle • A tensor • Lateral: thyromuscularis muscle • A relaxer

COUGHING

• Process: • deep inhalation • forceful adduction • significant subglottal pressure builds • vocal folds are forced open

• Expels foreign object (but irritates the vocal folds)

THROAT CLEARING

• Also use forceful adduction and vocal folds forced open by high subglottal pressure • Not reflexive • Repetitive throat clearing can cause functional voice disorders

ABDOMINAL FIXATION

tabilizes thorax • Requires vocal fold closure

This is why you stop breathing when you work out. since your vocal folds are closed

THE ONSET OF PHONATION

• Vocal folds move to an adducted position • LCA and IA achieve “medial compression” • Air flows from lungs, increases subglottal pressure (positive pressure) • Airflow forces folds apart, air escapes • Elasticity and negative pressure cause folds to close • Cycle repeats itself repeatedly

TERMINATION

A result of abducting the of vocal folds, • to stop phonation • to breathe • by contraction of the the Posterior Cricoarytenoid

VOCAL FOLD VIBRATION

110 Hz for men, ≅ 220 Hz for women, and above 300 Hz for children

Cycle

from one point on the waveform to the same point

Frequency of vibration

ow often a cycle of vibration repeats itself

Period

the time it takes to pass through one cycle of vibration

Frequency

physical measure, cycles per second, measured in Hertz

Pitch

psychophysical measure, one’s perception of frequency • The faster the frequency, the higher the pitch you will perceive

PHYSICAL PROCESS OF VIBRATION

The fundamental frequency (Fo) is determined by the physical attributes of the vocal folds: • Elasticity • Stiffness • Inertia

Elasticity

causes tissue to return to its original shape after being displaced

Stiffness

the strength within a material that restores it to its original shape on being distended

• Inertia

a body in motion tends to stay in motion

INFLUENCE OF PHYSICAL PROPERTIES

As mass increases, stiffness decreases, inertia increases, and the frequency of vibration decreases • As vocal fold stiffness increases, mass and inertia decrease, the vocal folds vibrate more rapidly

INTENSITY

magnitude of sound created by vibration of vocal folds (amount of excursion of vocal folds)

Loudness

a psychophysical measure, our perception of intensity

INTENSITY-CHANGING MECHANISMS

• An increase in subglottal pressure caused by • larger inspired volume of air • vocal folds remaining closed longer • increased medial compression

Intonation:

pitch patterns in an utterance

Stress

change in pitch at the word level • can change the meaning of a sentence

Nodules

come from yelling, screaming, singing, speaking outside of optimum pitch range

Polyps

• Similar to nodules • Function of allergies, thyroid imbalance, URI, smoking, alcohol abuse

• Tremor- NEUROLOGICAL DISORDERS

Pitch and loudness oscillations

NEUROLOGICAL DISORDERS

Spasms

• i.e. spasmodic dysphonia, no control over when phonation starts/stops

• Degenerative Diseases-NEUROLOGICAL DISORDERS

• Huntington’s, Parkinson’s, ALS