spa3101 chapter 4

Phonation

voicing, product of vibrating vocal folds, occurs within larynx, respiration provides energy

Biological functions of the larynx

produces phonation, clamps airway in response to possible intrusion by foreign objects, expels foreign matter away from airway opening

Vocal folds in biological function of larynx

vocal folds permit a person to hold their breath, important in swimming, lifting, childbirth, defecation

Laryngeal skeleton includes

hyoid bone, thyroid cartilage, arytenoid cartilage, cricoid cartilage, corniculate cartilages, epiglottis

Structure of the larynx

musculo-cartilaginous, at top of the last ring of the trachea

Larynx is adjacent to

cervical vertebrae 4 through 6

Three unpaired cartilages of larynx

cricoid, thyroid, epiglottis cartilage

Cricoid cartilage

complete ring atop the trachea, most inferior, articulates with thyroid via cricothyroid joint, higher in the back

Thyroid cartilage

largest laryngeal cartilage, articulates with cricoid cartilage via paired processes that allow it to rock back and forth

Superior cornu attaches to

greater cornu of hyoid

Epiglottis cartilage

leaflike cartilage, unpaired, protective structure during swallowing

Where is the epiglottis

behind hyoid at root of tongue, attached to inferior of thyroid cartilage below thyroid notch

Three paired cartilages of larynx

arytenoid, corniculate, cuneiform

Arytenoid cartilage position

ride atop cricoid cartilage, articulation with cricoid cartilage, posterior attachment of vocal folds

Corniculate cartilage

rides on superior surface of each arytenoid, landmark in the aryepiglottis folds

Cuneiform cartilage

reside within aryepiglottis folds, provide rigidity and stiffness to folds

Hyoid bone

u-shaped, union between the tongue and laryngeal structures, loosely articulates with the superior cornu of the thyroid cartilage, only bone of the body not attached to another bone, 23 muscles attached, unpaired

Three major elements of the hyoid bone

corpus (point of attachment for 6 muscles), greater and lesser cornu/horns (point of attachment for 3 muscles)

Laryngeal joints

cricothyroid and cricoarytenoid joints

Cricothyroid and cricoarytenoid joints attached via

the anterior, lateral, and posterior ceratocricoid ligaments

Cricothyroid motions

rotating (primary) and gliding

Cricothyroid joint function

tension of vocal folds for pitch

Cricoid and arytenoid cartilages attached via

anterior and posterior cricoarytenoid ligaments

Cricoarytenoid joint motions

rocking (primary) for abduction and adduction, gliding

Cricoarytenoid joint function

tensing of the vocal folds for approximation

Internal topography of larynx includes

laryngeal cavity, vocal folds, ventricular folds, laryngeal ventricles, laryngeal ligaments and membranes

Cavities of the larynx

aditus, vestibule

Aditus

entry to the larynx from the pharynx above

Vestibule

space between the aditus and the ventricular or vestibular folds

Ventricular folds

aka false vocal folds, not used for phonation, made of mucus membrane and vestibular ligament, contain ventricular ligaments and sparse muscle fibers

Aryepiglottic folds

flaps of mucus lining, lateral walls, run between arytenoid cartilages and epiglottis, envelop aryepiglottic muscles and cuneiform cartilages

The laryngeal cavity extends from

bottom of cricoid cartilage to laryngeal aditus

Laryngeal aditus comprises of

tops of arytenoid and corniculate cartilages, sides of epiglottis, aryepiglottic folds

Inner larynx

cartilages of larynx combined form a tube-like space with adjustable valve-like constriction

Medial laryngeal surface is covered in

mucous membrane

Vocal folds

are 2 muscles, under ventricle, 5 layers of tissue, deepest is muscle, in air stream at superior end of trachea

Glottis

space between vocal folds, most important laryngeal space for speech, defined by variable sphincter that allows voicing

Anterior and posterior pomiture

Subglottal

area below vocal folds

Fine structures of vocal folds

squamous epithelium, superficial lamina propria, intermediate lamina propria, deep lamina propria, thyroarytenoid muscle

Squamous epithelium

most superficial protective layer, appears white during exams, keeps moist

Superficial lamina propria

elastin fibers which can be extensively stretched

Intermediate lamina propria

deeper, elastin fibers for elasticity and strength

Deep lamina propria

supportive layer comprised of collagen fibers, prohibit extension

Intermediate and deep lamina propria combine form the

vocal ligament made of elastin

Thyroarytenoid muscle

make up bulk of vocal folds

Membranous part of vocal folds

anterior, lies between thyroid cartilage and tips of vocal processes of arytenoid cartilage, occupies 60% of strength

Cartilaginous part of vocal folds

posterior, lies between vocal processes and most rearward point on medial surface of arytenoid cartilages, occupies 40% of strength

Laryngeal ventricles

the depression or space between the false and true vocal folds. Contains mucous glands to lubricate

Intrinsic ligaments and membranes connect

laryngeal cartilages to one another

Extrinsic ligaments and membranes connect

hyoid or trachea and cartilage of the larynx

Lines the entire larynx

mucous membrane

Intrinsic ligaments support

structures of the larynx and vocal folds

intrinsic ligaments

fibroelastic membrane, upper quadrangular membranes, aryepiglottic folds, lower conus elasticus, vocal ligament

Pyriform sinus

space between the aryepiglottic fold and the thyroid cartilage for food and liquid transit

Conus elasticus

dominant membranous lining situated below vocal folds

Conus elasticus connects

cricoid, arytenoid, and thyroid cartilages

Conus elasticus gives rise to

middle cricothyroid ligament, lateral cricothyroid membranes, and vocal ligaments

Quadrangulus membrane connects

epiglottis, thyroid, arytenoid, and corniculate cartilages

Laryngeal extrinsic ligaments

thyrohyoid membrane, lateral thyroid ligament, triticeal cartilage, median thyrohyoid ligament

Hyoepiglottic ligament and thyroepiglottic ligament attach

epiglottis to hyoid

Lateral and median glossoepiglottic ligaments

epiglottic attachment to the tongue, produce vallecula

Trachea attached through

cricotracheal ligament

Crichotracheal membrane connects

cricoid cartilage to tracheal rings

Hyothyroid membrane connects

hyoid bone to thyroid cartilage

Passive force

recoil of muscles, cartilages and connective tissue, gravity

Active forces

intrinsic muscles, extrinsic muscles, supplementary muscles

Intrinsic laryngeal muscles have

both attachments inside the larynx, fine adjustments to vocal mechanism, innervated by vagus nerve

Intrinsic laryngeal muscles function

opening, closing, tensing, relaxing vocal folds

Intrinsic laryngeal muscles types

adductors, abductors, tensors

Intrinsic laryngeal adductors

lateral cricoarytenoid, transverse arytenoid, oblique arytenoid

Intrinsic laryngeal abductor

posterior cricoarytenoid

Intrinsic laryngeal tensors

cricothyroid, thyrovocalis

Lateral cricoarytenoid

act in opposition to posterior cricoarytenoid muscles, rotates arytenoid cartilage on their axes which closes the glottis, adductor

Arytenoid two parts

transverse arytenoid, oblique arytenoid

Transverse arytenoid

originates on posterior surface of one arytenoid, inserts on same location on other arytenoid, only unpaired intrinsic laryngeal muscle,

Contraction of transverse arytenoid

pulls arytenoid cartilages toward each other, tightening of glottal closure

Oblique arytenoid

originates from back and side of muscular process of arytenoid and inserts in the apex of the other arytenoid

Contraction of oblique arytenoid fibers

tilt the apex of each arytenoid cartilage together

Posterior cricoarytenoid origin and insertion

originates on back of cricoid cartilage and inserts into upper and back surfaces of muscular process of the arytenoid cartilage

Contraction of posterior cricoarytenoid

they draw the muscular processes posteriorly and inferiorly, rotates arytenoids so that they move away from midline and up, abducts vocal folds and opening glottis

Contraction of aryepiglottic muscle

pulls epiglottis backward and downward to cover larynx

Intrinsic laryngeal relaxers

thyromuscularis

auxiliary musculature

thyroepiglottic, superior thyroarytenoid, aryepiglottic muscle

Cricothyroid parts

pars rectus and pars oblique

Cricothyroid originates

from outer front and side of anterior arch of the cricoid cartilage and inserts on the outer front and side of lower border of the lamina and inferior cornu of thyroid cartilage

Contraction of cricothyroid

increases distance between upper border of cricoid and lower border of thyroid cartilage

Contraction of thyroarytenoid

reduces distance between thyroid and arytenoid cartilages to shorten folds and increase tension

vocal fold is composed of

vocal ligament, thyrovocalis, thyromuscularis

Thyromuscularis is a

relaxer

Thyrovocalis is a

tensor

The thyromascularis is innervated by

recurrent laryngeal nerve

Thyroarytenoid muscle originates

from inside surface of thyroid cartilage and inserts on ipsilateral arytenoid cartilage

Extrinsic laryngeal muscles attachment

one attachment inside the larynx and one outside the larynx, elevate and depress larynx, important in swallowing

Supplemental laryngeal muscle attachments

both attachments outside larynx, but influence larynx through hyoid

Supplemental laryngeal muscles types

infrahyoid (below hyoid), suprahyoid (above hyoid)

Sternothyroid

extrinsic infrahyoid, originates on sternum, inserts on thyroid

Contraction of sternothyroid

pulls thyroid cartilage down

Thyrohyoid

infrahyoid, originates on outer surface of thyroid cartilage and inserts on low end of greater cornu of hyoid bone