4. Anatomy of Phonation

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Larynx - cartilaginous structure holding the vocal folds which protrude into
airstream
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Flow increase - like thumb over garden hose
Pressure drop - narrower space forces pressure drop due to speed of air
Voiced - voiceless sounds
PhonationAnatomy
glottis, subglottal region,
Biological function -protection of airway
-seal during swimming
-seal to provide base for muscles
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One cycle of vocal fold vibration
A. Air from lungs hits adducted folds
B. Pressure parts folds inferiorly
C. Superior aspects of folds opens
D. Folds blown apart, flow between folds increases and
pressure decreases
E. Decreased pressure and elastic quality of folds causes folds
to return toward
midline
F. Folds make contact inferiorly
G. Vibration cycle completed
Although specific muscles cause movement, actual vibration is product of
airflow interacting with tissue in absence of repetitive muscle contraction
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Three paired and three unpaired cartilages
Tube with smooth and reasonably aerodynamic surface
1. Cricoid - ring shaped, narrow anteriorly
Sheets and cords of ligaments connect cartilages with smooth mucous
2. Thyroid - articulates with cricoid through paired processes which let it rock
membrane covering medial-most surface
forward and backward, anterior vocal fold attachment
Thyrohyoid membrane, lateral thyrohyoid ligament, and median thyrohyoid
3. Arytenoids (paired) - posterior point for attachment of vocal folds ride
ligament cover space between hyoid and thyroid
upon posterior portion of cricoid cartilage
Hyoepiglottic and thyroepiglottic ligaments attach epiglottis to the hyoid and
4. Corniculates (paired) - rest upon arytenoids
thyroid
5. Cuneiforms (paired) - rest within the aryepiglottic folds atop corniculates
Cricotracheal ligament attaches trachea to larynx
6. Epiglottis - medial to thyroid and hyoid - protective as it covers larynx
Ventricle folds (false) and vocal folds separated by laryngeal ventricle
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Five layers
1. Squamous epithelium - extremely thin - gives vocal folds the pearly white
appearance
2. Lamina propria
a. Elastin fibers - random orientation allowing stretching
b. Elastin fibers - anterior/posterior orientation
c. Collagen fibers - anterior/posterior orientation but prohibits extension
3. Thyrovocalis muscle Some authors
mucosal lining - 1 and 2a layer
vocal ligament - 2b and 2c (giving stiffness and structure)
Other authors
cover - 1, 2a and 2b
body - 2c and 3
Valleculae - “little valleys” formed by membrane between tongue and
epiglottis
Glottis - space between folds, usually approximately 20mm in adults
Anterior commissure - anterior most opening
Posterior commissure - between the arytenoid cartilages
Cuneiform cartilages - embedded within the aryepiglottic folds - provide
support for membranous covering
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Viewed as expanded tracheal cartilage
Would loosely fit on little finger
Arytenoids - one of most important of larynx
Union between tongue and larynx (although not bone of larynx)
rest on posteriolateral surface of cricoid
-articulates loosely with superior cornu of thyroid
1. apex - below corniculate cartilages
-only bone in body not attached to another bone
2. base - inferior surface is concave and articulates with convex arytenoid
facet of cricoid
3. Vocal process - projects anteriorly toward thyroid notch and serves as
attachment for vocal folds (thyrovocalis muscle)
4. Muscular process - attachment for muscles which adduct and abduct
folds (thyromuscularis muscle)
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1. Cricothyroid joint - synovial joint of cricoid and inferior cornu of thyroid
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2. Cricoarytenoid joint - synovial joints between concave arytenoid base and
-permits thyroid to rock down in front and slightly glide forward and
convex cricoid cartilage
backward
-permits rocking, gliding and minimal rotation
-provides major adjustment for changes in vocal pitch
A. Arrows show rocking movement as result of articular facet
B. Long axis of facet allows permits anterior/posterior gliding
C. May also rotate.
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Origin - superior-lateral surface of cricoid cartilage
Insertion - muscular process of the arytenoid
Innervation - X (vagus), recurrent laryngeal nerve, inferior laryngeal nerve
Function - adducts vocal folds, increases medial compression
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Transverse arytenoids
Origin - lateral margin of posterior arytenoid
Insertion - lateral margin of posterior surface opposite arytenoid
Innervation - X (vagus), recurrent laryngeal nerve
Function - adducts vocal folds
Oblique arytenoids
Origin - posterior base of muscular process of arytenoid
Insertion - apex of opposite arytenoid
Innervation - X (vagus), recurrent laryngeal nerve
Function - pull apex medially
Posterior Cricoarytenoids
Origin - posterior cricoid lamina
Insertion - posterior aspect of muscular process of arytenoid
Innervation - X (vagus), recurrent laryngeal nerve
Function - abducts vocal folds
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Cricothyroid pars recta
Origin - anterior surface of the cricoid beneath arch
Insertion - thyroid between lamina and inferior horns
Innervation - External branch of superior laryngeal nerve of X (vagus)
Function - depress thyroid relative to cricoid, tense vocal folds
Cricothyroid pars oblique
Origin - cricoid lateral to pars recta
Insertion - lower surface of thyroid lamina
Innervation - External branch of superior laryngeal nerve of X (vagus)
Function - depress thyroid relative to cricoid, tense vocal folds
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Thyrovocalis (medial thyroarytenoid)
Superior thyroarytenoid (thyroepiglottis)
Origin - inner surface thyroid cartilage near notch
Origin - inner surface thyroid cartilage near angle
Insertion - lateral surface of arytenoid vocal process
Insertion - muscular process of arytenoid cartilage
Innervation - X (vagus) recurrent laryngeal nerve
Innervation - X (vagus) recurrent laryngeal nerve
Function - tense vocal folds
Function - relaxes vocal folds
Thyromuscularis (lateral thyroarytenoid)
Origin - inner surface thyroid cartilage near notch
Thyroepiglottis: also known as the superior thyroarytenoid muscle. Some
anatomists say this muscle is not present in all individuals. It originates higher
on the internal surface of the thyroid cartilage and has a more oblique direction
back down toward the muscular process of the arytenoid where it inserts. When
present this muscle seems to serve as a relaxer of the vocal fold. It may also
possibly be responsible for changing and controlling the internal dimensions of
the epilarynx and false vocal folds.
Insertion - muscular process and base of arytenoid cartilage
Innervation - X (vagus) recurrent laryngeal nerve
Function - relaxes vocal folds
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Diagastricus anterior (also considered muscles of mastication)
Stylohyoid
Origin - inner surface of mandible near symphysis
Origin - styloid process of temporal bone
Insertion - hyoid (by means of intermediate tendon)
Insertion - corpus hyoid
Innervation - Cranial V (Trigeminal), mandibular branch (via
mylohyoid branch of
Innervation - Cranial VII (Facial), motor branch
Function - elevates and retracts the hyoid bone
inferior alveolar nerve
Function - draw hyoid up and forward
Diagastricus posterior (also considered muscles of mastication)
Origin - mastoid process of temporal bone
Insertion - hyoid (by means of intermediate tendon)
Innervation - Cranial VII (Facial), digastric branch
Function - draw hyoid up and back
Together these elevate hyoid
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Mylohyoid
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Geniohyoid
Origin - inner surface of mandible, mylohyoid line
Origin - inner surface of mandible, mental spines
Insertion - corpus hyoid
Insertion - corpus hyoid
Innervation - Cranial V (Trigeminal), mandibular branch
Innervation - Cranial XII (hypoglossal) and C1 spinal
Function - elevates hyoid and depresses mandible
Function - elevates hyoid and depresses mandible
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Hyoglossus
Genioglossus
Origin - greater cornu of hyoid
Origin - inner surface of mandible, mental spines
Insertion - side of tongue
Insertion - tongue and corpus hyoid
Innervation - Cranial XII (hypoglossal) motor branch
Innervation - Cranial XII (hypoglossal) motor branch
Function - elevate hyoid depresses tongue
Function - elevate hyoid depresses, retracts and protrudes tongue
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Inferior Pharyngeal Constrictor (Thyropharyngeus)
Origin - posterior pharyngeal raphe
Insertion - thyroid lamina and inferior cornu
Innervation - X (vagus) recurrent laryngeal nerve (external laryngeal
branch) and X superior laryngeal nerve (pharyngeal branch) and XI
(Accessory)
Function - elevates and constricts pharynx
Sternohyoid
Sternothyroid
Origin - manubrium sterni and clavicle
Origin - manubrium sterni
Insertion - inferior margin of hyoid corpus
Insertion - oblique line thyroid cartilage
Innervation - ansa cervicalis from C1-C3
Innervation - spinal nerves C1-C3
Function - depresses hyoid
Function - depresses thyroid cartilage
Omohyoid, superior and inferior heads
Thyrohyoid
Origin - superior - corpus hyoid
Origin - oblique line thyroid cartilage
Inferior - upper border of scapula
Insertion - greater cornu hyoid
Insertion - corpus hyoid
Innervation - Cranial XII (hypoglossal) and fibers from spinal C1
Innervation - ansa cervicalis from C1-C3
Function - depresses hyoid and elevate thyroid
Function - depresses hyoid
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