Laryngeal Anatomy
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Extrinsic Laryngeal Muscles
• Three Main Purposes:
1) Fixation (primary role)
2) Elevation (move larynx up)
3) Depression (move larynx down)
• Two major groups of extrinsic muscles
Suprahyoid & Infrahyoid
• Anatomical position:
Suprahyoid- one of the above
attachments lies above the larynx.
Infrahyoid- one of the attachments lies
below the larynx.
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Extrinsic Laryngeal Muscles
• Suprahyoid Muscles:
1) Digastric
2) Geniohyoid
3) Hyoglossus
4) Mylohyoid
5) Stylohyoid
• Function: Raise the hyoid bone &
indirectly raise the larynx.
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Digastric
• Two fleshy bellies
• Anterior belly- originates from the inside surface of
the lower border of the mandible near the symphysis
and inserts into the lesser horn of the hyoid bone
• Posterior belly- Originate from the mastoid process of
the temporal bone to the sternocleidomastoid muscle
• Two bellies meet and are joined by an intermediate
tendon
• Contraction raises hyoid or if hyoid is fixed, may
assist in depressing lower jaw
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Stylohyoid
• Superficial to the diagastric
• Originates from posterior and lateral surface
of the styloid process of the temporal bone &
inserts into hyoid bone
• Contraction draws the hyoid bone up and
backward
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Mylohyoid
• Forms muscular floor of mouth
• Originate from the mylohyoid line (inner surface
of mandible)
• Fibers coarse medially and downward and join the
other paired muscle at the raphe
• Posterior fibers attach right to hyoid bone
• Contraction elevates the hyoid, floor of mouth and
tongue
• Hyoid fixed, may assist in depressing mandible
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Geniohyoid
• Paired, cylindrical muscle located above the
superior surface of the mylohyoid muscle
• Originate by means of a short tendon, from
the lower part of the mental symphysis
• Insert into anterior surface of the hyoid
• Mandible fixed, this muscle pulls the hyoid
bone up and forward
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Hyoglossus
• Extrinsic muscle of the tongue
• Influences position of the larynx
• Arises from upper border of the body
and greater horns of the hyoid bone
• Inserts into posterior and lateral
regions of the tongue
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Genioglossus
• Extrinsic tongue muscle which influences position
of the larynx
• Originates from the mental symphysis
• Fibers fan out and course toward their insertion
• Lower fibers insert into the body of the hyoid
bone
• Upper fibers insert into the under surface of the
tongue
• Contraction elevates the hyoid bone and draws it
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forward
• Infrahyoid Muscles:
1) Sternohyoid
2) Omohyoid
3) Sternothyroid
*All are considered laryngeal depressors
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Sternohyoid
• Flat muscle lying on the anterior surface of the
neck
• Originates from the posterior surface of the
manubrium of the sternum from the medial end of
the clavicle and from the ligamentus tissue
• Fibers coarse vertically and insert on the lower
border of the body of the hyoid
• Acts to draw the hyoid bone downward and fixes
the hyoid when the lower jaw is open against
resistance
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Omohyoid
• Long, narrow 2 bellied muscle
• Located on the anterolateral surface of the
neck
• Inferior belly originates from the upper horn
of the hyoid
• Prevents the neck region from collapsing
during deep inspiration
• Prevents blood vessels of the neck from
being compressed
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Extrinsic laryngeal Muscles
Mandible
Ant.
Digastric
Post.
Digastric
Stylohyoid
Mastoid Tip
Mylohyoid
Hyoid Bone
Thyrohyoid
Sternohyoid
Omohyoid
Sternothyroid
Sternum
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Intrinsic Laryngeal Muscles
• Functions:
1) Abduction of the vocal folds
for respiration,
2) Fine discrete movements
during voice production &
closure of the vocal folds and,
3) Protection of the trachea.
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More Specifically...
• change the degree of abduction/
adduction
• change the mass characteristics of the
folds
• change the tension of the folds
• change the length characteristics of the
folds
• react during swallowing- closure of folds
• assist in muscular mechanical advantage
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Intrinsic Muscles:
Action of Cricothyroid
Pars oblique
Pars recta
• Cricothyroid: fan-shaped, 2 divisions,
Lengthens & tenses the vocal folds.
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Intrinsic Muscles
Thyroarytenoid
Vocal ligament
Thyrovocalis
Thyromuscularis
• Thyroarytenoid: muscle making up the true vocal
folds, 2 parts: thyrovocalis (bound to the vocal
ligament) & thyromuscularis (lateral to arytenoids).
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Thyroarytenoid Functions
• decreases the distance between the
thyroid & arytenoid cartilage's,
• shortens the folds,
• decreases tension
• decreases pitch of the voice,
• active contraction lowers pitch of the
voice.
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Intrinsic Muscles
Action of Post.
Cricoarytenoid
Posterior
Cricoarytenoid
• Posterior Cricoarytenoid: Abducts the vocal folds,
actively contracted at the end of phonation & any
speech sound not requiring v.f. vibration.
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Intrinsic Muscles
Action of Lat.
Cricoarytenoid
Lateral
Cricoarytenoid
• Lateral Cricoarytenoid: lies along upper surface of
cricoid cartilage, adducts vocal processes of
arytenoids closing membranous portion of v.f.’s. 20
Intrinsic Muscles
Transverse
Interarytenoids
Oblique
Interarytenoids
• Interarytenoids (transverse & oblique):
Unpaired, 2 part muscle, adducts the v.f.’s
in the cartilaginous portion by pulling
arytenoid tips together.
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The Glottis
Glottis
•
•
•
•
The glottis is an open space between the vocal folds.
Size is dependent on what position the v.f.’s are in.
Not a muscle or cartilage.
Abduction- open v.f.’s; Adduction- closed v.f.’s
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Ventricular Folds
• Otherwise know as the False Folds,
• superior & lateral to the true vocal folds,
• Their role in phonation?
-No role in voicing
• consist of muscle, but doesn’t have
innervation for discrete movements,
• Hyperfunctional voice?
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Activity
1) With you mouth open, hold your breath,
then abruptly release it with a vocal tone.
What physiologic events occur at the glottis?
2) Produce an /h/ sound alone. What is the
status of the glottis? How did it get there?
3) Produce an /h/ sound, then slide into
phonation. What muscles are contracting to
affect what conditions in the glottis?
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More questions...
1) Place your finger on the laryngeal
prominence, alternate between high
and low pitched tones. Can you
identify a change in the position of the
larynx and describe the prime movers?
2) Can you phonate while inhaling?
What are the physiological
differences?
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Reading/Assignments
• Seikel: Pgs. 183-202
• Dickson: Pgs. 160-176
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