Anatomy Of Phonation

Voicing that occurs as a result of vibrating vocal folds
*Cerebration-Source of thought
*Respiration-Source of energy
*Phonation Source of voice

*Sits at the top of the trachea
*Located between trachea and hyoid bone (C3-C6)
*Houses vocal folds
*Biological function is airway protection, secondary is phonation.

*Extension of tracheal rings
*Comprised of cartilage and muscle
*Suspended by muscles, ligaments, membranes, one bone (hyoid)
*Surrounded on three sides by pharynx

*Support for base of tongue
*Does not connect to any other bones in the body
*Landmarks
-Corpus (body)
-Minor horns (cornu) aka lesser horns
-Major horns (cornu) aka greater horns

*Largest, most superior cartilage
*Landmarks
-Lamina-front part sticks out
-Angle
-Notch
-Superior/Inferior cornu
-Oblique line
(most prominent part of larynx)
*see diagram for placement*

*Expanded tracheal cartilage
*Inferior part of larynx
*Connects to thyroid at cricothyroid joint
*Landmarks
-Arch
-Lamina
-Anterior facets for artyenoid and thyroid
(logical, cricothyroid joint is where thyroid and cricoid meet)

The arch of the cricoid cartilage is anterior.
The lamina is on the side
There is a facet for thyroid and a facet for the arytenoid
*See page 180 for details.

*Provides movement for vocal folds
*Landmarks
-Apex: sits on top of the pyramid base
-Base
-Muscular process-point of attachment for muscles that adduct (close)/abduct(open) vocal folds
-Vocal process-projects anteriorly toward thyroid notch, point of attachment for posterior portion of vocal folds.
*arytenoids sit on top of cricoid cartilage posteriorly (top part of the signet part of the signet-shaped cricoid)

*Forms peak of arytenoid cartilage
*On superior surface of each arytenoid
*Projects posteriorly (back)

*Embedded in tissue running between arytenoids and epiglottis
*Stiffens vocal folds and aids in abduction

*Leaf shaped
*Flexible, highly elastic tissue
*Behind the hyoid bone and base of tongue
*Attaches to other structures by ligaments
*Forms aryepiglottic folds
*Protects airway, directs food to esophagus
*No speech function
(main idea: protects airway and shoots the food in the right direction)

*Connects cricoid with inferior cornu of thyroid
*Allows thyroid to rock forward & down
*Tenses and elongates vocal folds
(this adjusts pitch, when rocks forward and down, pitch goes up bc chords are stretched)

*Joins superior cricoid (signet ring) surface (convex) with base of arytenoid (concave)
*Allows arytenoids to rock/glide/rotate
*Allows vocal process to move toward each other and vocal folds to approximate

*Extrinsic-provides attachment between hyoid or trachea and laryngeal cartilage.
-thyrohyoid membrane
-Hyoepiglottic ligament
-Thryoepiglottic ligament
-Cricotracheal membrane
-Glossoepiglottic ligament

*Intrinsic-Connect cartilages of the larynx and form support structure for laryngeal cavity and vocal folds (Within larynx)
*Quadrangular membrane-from arytenoids to epiglottis and thyroid cartilage
*Conus elasticus-From margins of TVF (true vocal folds) to inferior cricoid
-Vocal ligament is superior part of conus elasticus

*Aditus: rim of epiglottis (like door)
*Vestibule: Space between aditus and FVF (false vocal fold, also known as ventricular folds. not used in phonation)
*Ventricle: Space between true vocal folds and false vocal folds
*Glottis: Variable space between True vocal folds
*Subglottic Space: Below true vocal folds

*Space between vocal folds-most important space for speech. It's defined by a variable sphincter that permits voicing (variable bc chords can move)
*About 20 mm long in adults, anterior-posterior commissures. The anterior commisure is the anterior most opening (near thyroid notch) posterior to the angle of they thyroid cartilage. The posterior commissure is between the arytenoid cartilages.
*Membranous glottis: anterior 3/5, more vibrations possible
*Cartilagenous glottis posterior 2/5

*5 layers of different types of tissues:
-Epithelium on surface (protective most superficial, causes white appearance of vocal chords, assists with fluid retention and helps keep chords moist)
-Lamina propia (3 layers) deep to epithelium. Superficial and intermediate are made up of elastin fibers which cushions the vocal folds and allows for extensive streaching. Provides elasticity and strength. Deep lamina propria is made of collagen fibers that prohibit extension and provides support. The ILP and DLP (intermediate & deep lamina propria) combine to form the vocal ligament where both elastin and collagen provide stiffness and support to vocal folds.
-Thyroarytenoid muscle: Two muscle parts provide bulk of chords (thyrovocalis & thyromuscularis)

*Posterior commissure
*Proximal trachea
*True vocal fold
*False vocal fold
*Anterior commissure

*Both origin and insertion on laryngeal cartilages, make fine adjustments to vocal mechanism. Change pitch. Makes fine adjustments by opening, closing, tensing, relaxing vocal folds. All are paired except for the transverse arytenoid

*One attachment on laryngeal cartilage, other on a nonlaryngeal structure, make major adjustments to larynx. Swallow & moves hyoid.

*Close vocal folds for airway protection and phonation (want closed when eating and swallowing)
-Lateral cricoarytenoid
-Transverse arytenoid
-Oblique arytenoid

Origin: Superior lateral surface of cricoid
Course: Up and back
Insertion: Muscular process of arytenoid
Function: Adducts vocal folds by inward, downward rocking of arytenoids. Closes chords. pg 190.

Origin: Lateral margin of posterior arytenoid muscle
Course: laterally
Insertion: Lateral margin of posterior surface of opposite arytenoid
Function: Adducts vocal folds
*Also known as transverse interarytenoid muscle. looks like a band.

Origin: Posterior base of musclular processes of arytenoids
Course: Up and medial, cross midline to form "X"
Insertion: Apex of opposite arytenoid
Function: Pulls apex medially, adducting vocal folds. Close chords. Also called Oblique interarytenoid muscle. Immediately superficial to the transverse arytenoid.

Opens vocal fold for breathing and cessation of phonation (stop talking)
-Posterior cricoarytenoid muscle

Origin: Posterior cricoid lamina
Course: Up and lateral
Insertion: Musclular process of arytenoid
Function: Abduct vocal folds (abductor)

Increase tension of vocal folds for pitch variation
-Cricothyroid
-Thyrovocalis

Origin: Anterior surface of cricoid cartilage
Course: Up, lateral
Insertion: Inferior surface of thyroid lamina
Function: Tenses vocal folds by depressing thyroid relative to cricoid. Thyroid moves forward and stretches vocal fold to make pitch higher.
*There are two parts to the cricothyroid, and this is anterior (muscles before were posterior)-tensor

Origin: Cricoid cartilage lateral to pars recta (oblique means side)
Course: Obliquely up
Insertion: Thyroid cartilage between laminae and inferior horns
Function: Tenses vocal folds by depressing thyroid relative to cricoid

Origin: Inner surface of angle of thyroid
Course: Back and down
Insertion: Lateral and inferior aspects of vocal process of arytenoid cartilages
Function: Tenses vocal folds. Does not move anything.
*AKA vocalis muscle, lateral to vocal ligament. widely debated and confusing whether it's two muscles or not.

Decreases tension of vocal folds for pitch variation
-Thyromuscularis

Origin: Inner surface of the thyroid cartilage
Course: Posterior
Insertion: Muscular process and base of arytenoid (more posterior)
Function: To relax vocal folds. When contracts, it rocks arytenoid. chord becomes bulky. AKA muscularis, lateral to vocalis.

One attachement to laryngeal cartilage, classified as laryngeal elevators or depressors according to function.
*Elevators: Digastricus, stylohyoid, mylohyoid, geniohyoid, hyoglossus, genioglossus, thyropharyngeus
*Depressors: Sternohyoid, omohyoid, sternothyriod, thyrohyoid

Origin: Inner surface mandible, near symphsis
Course: Medial, down
Insertion: Hyoid, via intermediate tendon
Function: Draws hyoid up and forward
*2 bellies (anterior/ posterior), overall function to elevate hyoid. For swallowing.

Origin: Styloid process of temporal bone
Courses: Down and medially, around digastris
Inserts: Corpus of hyoid
Function: Move hyoid posteriorly
*Moves hyoid back

Origin: Mastoid process of temporal bone
Course: Medial, down
Insertion: Hyoid, via intermediate tendon
Function: Draws hyoid up and back
*Right next to stylohyoid. Same function and works same way

Origin: Inside mandible, mylohyoid line and converge at median raphe
Course: Down, fanlike
Insert: Hyoid
Function: Elevates hyoid, depresses mandible, forms floor of oral cavity
*Clue: looks like fan. Forms floor of mouth.

Origin: Mental spines, inner surface of mandible
Course: Back and down, parallel to anterior digastris
Insertion: Corpus, hyoid bone
Function: Elevates hyoid, depresses mandible. Swallowing function.

Origin: Superior surface of greater cornu of hyoid
Course: Up
Insert: Sides of tongue
Function: Depresses tongue, elevates hyoid
*Top of hyoid. It's big. lowers tongue.

Origin: Inner surface of mandible at symphsis
Course: Up and back
Insert: Tongue and anterior surface of corpus of hyoid
Function: Elevates hyoid

Origin: Thyroid lamina, inferior cornu
Course: Up and out
Insert: Posterior pharyngeal raphe
Function: Constricts pharynx, elevates larynx
(B doesn't care about this one much)

Serve as antagonists to elevators and stabilize tongue

Origin: Manubrium sterni and clavicle
Course: Superior
Insert: Inferior Margin of hyoid corpus
Function: Depress hyoid

Origin: Intermediate tendon
Course: Up to hyoid
Insert: Through intermediate tendon-hyoid
Function: Depress hyoid.

Origin: Scapula
Course: Up
Insertion: Intermediate tendon
Function: Depress hyoid

Origin: Manubrium sterni, 1st costal cartilage
Course: Up and out
Insert: Oblique line of thyroid cartilage
Function: Depress thyroid cartilage in swallowing
*Pulls thyroid down

*Origin: Oblique line of thyroid cartilage
Course: Up
Insert: Inferior margin of greater cornu of hyoid
Function: Depress hyoid, raise larynx
*Superior counterpart to sternothyroid

*Safe swallowing-the epiglottis deflects true and false chords close to keep food and foreign bodies out of the lungs.
*Coughing-the response by tissues of the respiratory tract. Forceful evacuation of the respiratory passageway. You take a deep inhalation though widely abducted vocal folds, then the vocal folds tense and tightly adduct closed. The larynx elevates and then there is a forceful expiration, blows chords open.
*Throat clearing-is considered the near cousin of the cough. Less forceful but still stressful for the larynx.
*Abdominal fixation-The process of impounding air in the thorax to stabilize the torso. Used for lifting, bearing down, child birth. Take large inspiration and tightly adduct chords.

*Vocal folds: paired bands of tissue situated on both sides of larynx, intrude into airstream
-Any constriction in the airway greatly increases airway turbulence (air wants to come up trachea like a cylinder, but chords are in way. turbulence within fluid or gas is caused by irregularity in its passage-like hand out of window of car)
-Vocal folds cause air to have to detour
-Bernoulli Effect

Given a constant flow of air or fluid, at a point of constriction there will be a decrease in air pressure perpendicular to the flow and an increase in velocity of the flow.

You put constriction in a tube (trachea/chords), air flows faster as it flows through constriction and pressure on the wall at the point of constriction will be lower than that of the surrounding area. Like a garden hose and thumb. Speed is greater at thumb point, decreased internal pressure.
*P=F/A (pressure is force exerted on an area)
*Reminder: when air molecules flow through an area of constriction the same volume of air has to squeeze through a smaller space. So, each unit becomes longer and narrower (oval), exerting less pressure on the walls because it's distributed over a greater surface area.

*Initiation: Sufficient subglottic air pressure (Psg) to abduct vocal folds (open) and set chords into vibration. Once air hits chords, air vibrates bc they are muscles & aerodynaic. keep vibrating. wants to return to rest (gently closed)
*Continuance of vibration via elastic restoring forces in VF, inertia, stiffness. True VF vibrate.
*Stoppage: Decrease in air pressure, VF removed from path of airflow
*Repeated abduction and adduction not necessary once set into vibration. VF held in place during sustained phonation bc of aerodynamic interactions with the elastic characteristics of the vocal folds and their tonicity, which is sustained contraction of musculature. Not repeated abduction/adduction. Gently closed chords are at rest. air can still get though.

*From 1 point in a pattern to the same point
*Period: Amount of time for 1 cycle of vibration
*Frequency: Fow often a cycle repeats, measured in Hz (cycles/second)

VF open from bottom to top and close from bottom to top

VF open from back to front, close from front to back

*Vocal attack: Movement of vocal folds into airstream for purpose of initiation phonation
-Simultaneous vocal attack: coordinate adduction and expiration so they occur simultaneously
-Breathy vocal attack: Airflow begins prior to adduction
-Glottal attack: Expiration occurs after adduction

*Remove VF from airstream by abduction
*Once out of airstream, turbulence reduced and VF stop vibrating
*We terminate/initiate phonation many times during speech for voiced/voiceless sounds

*VF held in place during tonic (sustained) phonation
*Thyrovocalis and Thyromuscularis hold sustained posture of VF
*"Steady state" phonation to control fundamental frequency and stabilize intensity
*Not 2* repeated abduction/adduction

*Psycological correlate of frequency, perceived frequency
*Fundamental frequency: primary frequency of vibration of VF

*Perceptual characteristic representing the ideal or most efficient frequency of vibration of vocal folds
-Function of mass, length, elasticity of folds
-Varies as function of gender, age

*Range of fundamental frequency for an individual, calculated as difference between highest and lowest frequencies
*Vocal mechanism capable of approximately 2 octaves of range

*Frequency of vibration of VF that is habitually used during speech
*Ideally, same as optimal pitch
*Increased vocal strain/fatigue exerted when continuously using non-optimal pitch

*If mass increases, vibration decreases and frequency decreases
*Actual mass of VF does not change, but is rearranged by lengthening
*When VF stretched by contraction of tensor muscles, mass of folds distributed over greater distance, reducing mass per unit length

*To increase pitch
-VF thinner, longer, more tense
-Muscles:thyrovocalis, cricothyroid
-Smaller vibratory surface due to stiffness
*To decrease pitch: VF less tense (relaxed) more mass.
-Muscle:thyromuscularis

*Psycological correlate of intensity, perceived intensity.
*To increase loudness
-increase Psg &
-medial compression

*Distinctive characteristic of a tone, does not include pitch or loudness
-Breathiness: excessive airflow permitted between VF when closed due to inadequate approximation
-Harshness: medial compression greatly increased as a result of forced adduction

Maintenance of childhood pitch despite having passed through puberty

Double voice (cold, nodules)

Harsh sound produced during respiration 2* obstruction in airway

VF not vibrating but +laryngeal tension to develop turbulence in airstream.

Can result from damage to the vagus nerve (CN X) typically unilateral with VF in paramedian position

Uni/bilateral formation of hardened tissue on vocal folds resulting from vocal abuse

Typically unilateral lesions (softer than nodules) resulting from single vocal trauma

Radical surgery 2* CA, varies in extensiveness but entire larynx may be removed