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The Phonatory System
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Outline
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ANATOMY OF THE PHONATORY SYSTEM
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Bones, Cartilages & Joints
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Ligaments and membranes
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Innervation of the larynx
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Muscles of the Larynx
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Laryngoscopic, coronal and dorsal views of larynx and associated
structures
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Vocal Fold Structure
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PHYSIOLOGY OF PHONATORY SYSTEM

Laryngeal function
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Description of vocal fold vibration
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Necessary & sufficient conditions for phonation
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The Larynx: Key Functions
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Airway Protection
Intrathoracic pressure generation
Valving for speech
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The larynx: in situ
larynx
thyroid gland
trachea
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Midsagittal section
Figure 37.3
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Spin 180º
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Superior view
dorsal
Vocal folds
ventral
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glottis
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Bones, Cartilages & Joints
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Skeletal Structure
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Figure 37.21
Hyoid Bone
Thyroid Cartilage
Cricoid Cartilage
Epiglottis
Arytenoid Cartilage
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Hyoid Bone, Thyroid Cartilage &
Epiglottis
Figure 37.21
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Figure 37.17
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Cricoid Cartilage
Figure 37.19
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Arytenoid Cartilages (paired)
Figure 37.20
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Laryngeal Joints
Movement Basics
 6 degrees of freedom possible
 Translation – 3 degrees
 Rotation – 3 degrees
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Pitch
Roll
Yaw
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Laryngeal Joints
Figure 37.21
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Joint Articulation
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Thyroepiglottic joint
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Cricothyroid joint
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pitch
Pitch
Translation
Cricoarytenoid joint
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Pitch and roll – rocking
Translation – sliding or
gliding
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Ligaments & Membranes: Epiglottis
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Hyoepiglottic l.
Thyroepiglottic l.
Glossoepiglottic folds
(median and lateral)
Aryepiglottic fold
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Ligaments & Membranes: Epiglottis
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Hyoepiglottic l.
Thyroepiglottic l.
Glossoepiglottic folds
(median and lateral)
Aryepiglottic fold
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Ligaments & Membranes:
Thyroid & Cricoid cartilages
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Thyrohyoid m.
Ceratocricoid l.
Conus elasticus
Vocal l.
Cricotracheal m.
Posterior Cricoarytenoid l.
Figure 37.21
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Conus Elasticus & Vocal Ligament
Figure 37.21
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Laryngeal Anatomy: “Surface
Geography” – Superior view
esophagus
Dorsal/Posterior
arytenoid
glottis
Pyriform sinus
True vocal fold
aryepiglottic fold
False (ventricular)
fold
epiglottis
Ventral/Anterior
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Anterior View of Larynx
Figure 37.31
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Interior view of larynx
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Figure 37.23
Coronal View
Rostral (superior)
Ventricular
(false) folds
Supraglottal cavity
(aditus)
ventricle
True vocal folds
glottis
Subglottal area
Caudal
(inferior)
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Coronal section
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Figure 37.23
Laryngeal Anatomy Posterior view
Laryngeal Vestibule (aditus)
Pyriform Recess (fossa)
Figure 36.28
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Nerve supply to larynx
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Cranial Nerve X (Vagus N.)
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provide motor supply to all intrinsic muscles
major nerve communicating sensory information
to the CNS
2 branches important for larynx
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Superior laryngeal nerve
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Internal branch – provides sensory supply
External branch – supplies cricothyroid m.
Recurrent laryngeal nerve
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Motor to all other intrinsic muscles
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Nerve supply to Larynx
Figure 37.26
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Figure 36.33
Nerve supply to Larynx
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Figure 37.28
Laryngeal Anatomy: The muscles
1. Intrinsic muscles
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Both origin and insertion are within the larynx
2. Extrinsic muscles
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An origin or insertion is within the larynx
3. Supplemental muscles
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No origin/insertion within the larynx, but affects the location
of larynx in the neck
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Intrinsic Laryngeal muscles
Key Actions
Position
 Adduct
 Abduct
Tension
 Tense
 Slacken
Length
 Lengthen
 Shorten
ADDUCTION
ABDUCTION
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Lateral cricoarytenoid (LCA)
Origin:
Superior edge of
lateral border of cricoid
cartilage
Insertion:
muscular process of
arytenoid
Action: adducts VF
Motor Supply: CN X
(recurrent laryngeal nerve)
Figure 37.22
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Lateral cricoarytenoid (LCA) Action
From Netter
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Posterior cricoarytenoid (PCA)
Origin:
Posterior (dorsal) surface
of cricoid cartilage
Insertion:
muscular process of
arytenoid
Action: abducts VF
Motor Supply: CN X
(recurrent laryngeal nerve)
Figure 37.22
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Posterior cricoarytenoid (PCA)
Figure 37.22
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Posterior cricoarytenoid (PCA) Action
From Netter
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Thyroarytenoid (TA)
Often considered to have 2 parts
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Vocalis

Thyromuscularis
Origin:
Internal surface of the thyroid
angle
Insertion:
Vocal and muscular process of
arytenoid
Action: shorten & adducts VF
Motor Supply: CN X
(recurrent laryngeal nerve)
From Netter
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Thyroarytenoid (TA)
Figure 37.22
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Thyroarytenoid (TA) Action
From Netter
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(Inter)arytenoid (IA)
Often considered to have 2 fiber types
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Oblique
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Transverse
Origin:
Posterior (dorsal) surface of
arytenoid surface
Insertion:
Posterior (dorsal) surface of
opposite arytenoid
Action: adducts VF
Motor Supply: CN X
(recurrent laryngeal nerve)
Figure 37.22
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Interarytenoid (IA) Action
From Netter
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Cricothyroid (CT)
Often considered to have 2 fiber types

Oblique
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Vertical
Origin:
ventral and lateral surfaces of
arch of cricoid cartilage
Insertion:
Caudal border of the thyroid
cartilage and anterior surface of
inferior horn
Action: lengthens and tenses VF
Motor Supply: CN X
(external branch of superior laryngeal
nerve)
Figure 37.22
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Cricothyroid (CT) Action
From Netter
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Summary of Key actions
Box 37.20
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Extrinsic laryngeal muscles
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refers to muscles with a single attachment to a
laryngeal cartilage
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Extrinsic muscles: Sternothyroid
Origin:
superior and posterior
portion of the sternum and
first costal cartilage
Insertion:
oblique line of thyroid
Action: depresses thyroid
cartilage
Motor Supply: C1-C3
Ansa cervicalis
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Extrinsic muscles: Thyrohyoid
Origin:
oblique line of thyroid
Insertion:
hyoid bone
Action: depresses hyoid or
elevates thyroid cartilage
Motor Supply: C1
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Ansa Cervicalis
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Ansa Cervicalis
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Supplemental laryngeal muscles
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no direct attachments to laryngeal cartilages
attach on/near the hyoid bone
“Suspends” larynx in the neck
may elevate or depress hyo-laryngeal complex
Suprahyoid muscles: muscles that attach to sites
rostral to the hyoid bone
Infrahyoid (aka ‘strap’) muscles: muscles that
attach to sites caudal to the hyoid bone
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Supra and infra hyoid muscles
Figure 37.7
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Geniohyoid
Figure 37.15
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Figure 37.8
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Mylohyoid
Figure 37.8
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Digastric and Stylohyoid
Figure 37.8
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Figure 37.7
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Hyoglossus
Figure 36.23
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Sternohyoid & Omohyoid
Figure 37.15
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Figure 37.8
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Sternohyoid & Omohyoid
Figure 37.7
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Flex.mpg
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Vocal Fold paralysis video
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Superior view
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“Layered” structure of vocal fold
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Basic Structure of the vocal fold
epithelium
connective tissue
superficial layer
tissue loosely connected to the other layers
intermediate layer
Lamina
propria
elastic fibers (stretchy)
Vocal ligament
deep layer
collagen fibers (not stretchy)
muscle (TA)
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Vocal Fold Lesions
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Laryngeal Physiology
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What is the function of the larynx?
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Protection
Pressure generation
Valving for speech
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Laryngeal function during Swallowing
Within the SLP scope of practice
Role of larynx in swallowing
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protect the airway from
food/liquids.
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Levels of protection
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True vocal folds
Ventricular folds (false folds)
Adduction and anterior motion
of arytenoids
“Retroflexion” of the epiglottis
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Posterior (dorsal)
Anterior (ventral)
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Videofluoroscopy tape
Figure 37.3
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What is the function of the larynx?
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Protection
Pressure generation
Valving for speech
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What did we see?
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Alternate opening and closing of the glottis
There are some distinct phases
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Opening phase (glottis is getting bigger)
Closing phase (glottis is getting smaller)
Closed phase (glottal opening is absent)
Different parts of the glottis opens and closes at different
times
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“wave like” action along length of vocal folds
If we could see it, the bottom of the fold opens first and closes
first (vertical phase difference)
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What did we see?
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Different parts of the glottis opens and
closes at different times
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“wave like” action along length of vocal folds
If we could see it, the bottom of the fold
opens first and closes first (vertical phase
difference)
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Why does phonation occur?
Aerodynamic-myoelastic theory of phonation
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Glottal vibration is the result of an interaction between aerodynamic
forces and vocal fold muscular forces
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Three things are necessary and sufficient for phonation to occur
1.
Adduction (often termed medial compression)
2.
Longitudinal tension (the vocal fold must have an appropriate
amount of tension along its length)
3.
Aerodynamic forces (pushing and pulling by air flow and pressure)
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Do we need a larynx to phonate?
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Insufflation test
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