The Larynx

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The Larynx

• Medical Science 531
• Spring 2008
• D. M. Conley

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Functions of the larynx

• Sound production (phonation).
  NOTE phonation speech.
• Regulates amount of air entering the lungs.
• Acts as a valve to prevent food in the pharynx
  from entering the trachea.
• Provides a sphincter as part of the Valsalva
  maneuver (bearing down, lifting heavy objects).

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Location of the larynx
Hyoid
C-4 thru C-6
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The larynx is part of the respiratory
system
More specifically, it is part of the conducting
portion of the respiratory tract the larynx
regulates the amount of air entering and leaving
the lungs ? Remember, air flow in the respiratory
tract is TIDAL (in and out, in and out, etc.).
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Laryngeal components
Yowsa! Look at all that stuff!

• Cartilages.
• Extrinsic ligaments.
• A cavity (airway) lined by a mucosa.
• Fibro-elastic membranes.
• Intrinsic skeletal muscles.
• Nerves, arteries, veins, and lymphatics.

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The skeleton of the larynx
5 Major cartilages Thyroid (1) Cricoid
(1) Epiglottis (1) Arytenoid (2)
Covered with mucous membranes and skeletal
muscles.
Cricothyroid joint (synovial)
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The skeleton of the larynx
All major cartilages are composed of hyaline
cartilage EXCEPT the epiglottis Elastic
cartilage
? Arytenoid cartilages are paired ? They are
shaped like pyramids perched atop the cricoid
cartilage
Crico-arytenoid joints (synovial)
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Sexual dimorphism in the laryngeal skeleton
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The arytenoid cartilages have vocal and muscular
processes
Anterior Posterior
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Minor laryngeal cartilages
Probably support the ary-epiglottic folds they
produce swellings called cuneiform and
corniculate tubercles.
Cuneiform cartilages Corniculate cartilages
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Epiglottis
Hyo-epiglottic ligament Thyro-epiglottic ligament
Leaf-shaped elastic cartilage. Blocks inlet of
larynx upon swallowing.
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The epiglottis is covered with a mucous membrane
Ary-epiglottic fold
Median and lateral glosso-epiglottic folds
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Extrinsic ligaments
The thyrohyoid ligaments has apertures for the
internal branch of the superior laryngeal nerve
and superior laryngeal vessels.
Thyrohyoid ligament Attaches the larynx to the
hyoid this explains why the larynx is elevated
during swallowing.
Median cricothyroid ligament (a.k.a.
cricothyroid ligament.
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Extrinsic ligaments

• Hyo-epiglottic ligament
• Cricotracheal ligament

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Cavity of the larynx
Air enters the cavity of the larynx through the
laryngeal inlet
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Laryngeal inlet
(a.k.a. aditus)

• The inlet is surrounded by the
• Ary-epiglottic folds.
• Epiglottis.
• Note the cuneiform and corniculate tubercles
  features of the ary-epiglottic folds.

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Cavity of the larynx
Vestibule Saccule Ventricle Infraglottic
cavity Trachea
Coronal section
Sagittal section
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LaryngoceleDilatation of the laryngeal saccule
Can develop in response to chronic elevated
intraglottic pressure (trumpeters,
glassblowers). Congenital predisposition?
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The walls of the laryngeal cavity contains two
vocal folds
Vestibular folds (a.k.a. false vocal
folds). Vocal folds (a.k.a. true vocal folds,
vocal cords).
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Rima vestibuli
The circumscribed region of the laryngeal cavity
that contains the (true) vocal folds is called
the glottis. The spaces between the left and
right vestibular and vocal folds are called the
rima vestibuli and rima glottidis, respectively.
Rima glottidis
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Fibro-elastic membranes of the larynx

• Binds together the cartilages of the larynx.
• Reinforces the walls of the laryngeal cavity.
• Supports the vestibular and vocal ligaments.
• Consists of two parts
• Quadrangular membrane.
• Conus elasticus.

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Quadrangular membrane

• Supports the walls of the vestibule.
• Its superior free margins are in the
  ary-epiglottic folds.
• Its inferior free margins form the vestibular
  ligaments in the core of the vestibular folds.

QM
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Conus elasticus

• Supports the walls of the infraglottic cavity.
• Its superior free margins form the vocal
  ligaments in the core of the vocal folds.
• The conus elasticus is the superior, internal
  continuation of the cricothyroid ligament i.e.
  it sometimes is called the cricovocal ligament.

CE
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Internal view of conus elasticus
Conus elasticus the superior, internal
continuation of the cricothyroid ligament.
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Summary Walls of the laryngeal cavity
Vestibular ligament (inferior free margin of
quadrangular membrane)
Vestibular fold
True vocal fold Vocal cord
Vocal ligament (superior free margin of conus
elasticus)
Mucous membrane intact on this side
Mucous membrane removed on this side
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Attachment of vestibular and vocal
ligaments
Anterior Both attach to internal angle of the
thyroid cartilage. Posterior Vestibular
ligament to supero-lateral arytenoid
cartilage. Vocal ligament to vocal process of
arytenoid cartilage.
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Conley-gram summary
Coronal section of larynx
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Laryngoscopy
Indirect Direct
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Living anatomy of larynx cavity
Ant Post
Note pearly appearance of vocal folds
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Nodules of vocal folds
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Hoarseness (trachyphonia) is a common symptom of
laryngeal disease
Inflammation/lesions prevent proper movement/
vibration of vocal folds
Carcinoma
Laryngitis and polyp
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Movements of the arytenoid cartilages and the
vocal folds

• The arytenoid cartilages are able move in two
  ways
• Rotation
• Gliding

Folds together Adduction Folds apart Abduction
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Intrinsic muscles of the larynx
Skeletal muscles innervated by the vagi
Superior laryngeal nerve
Muscles of phonation do these tasks

• Perform 4 basic actions
• ? Abduct the vocal cords.
• ? Adduct the vocal cords.
• Tense/relax the vocal cords.
• Close the laryngeal inlet.

Recurrent laryngeal nerve
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Muscles that abduct the vocal cords
Posterior crico-arytenoid muscles
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Muscles that adduct the vocal cords
Lateral crico-arytenoid muscles transverse
arytenoid muscles.
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Muscles that tense the vocal cords
Cricothyroid muscles
Thyroid cartilage tilts forward on cricoid
cartilage vocal cords are stretched and become
taut.
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Muscles that relax the vocal cords
Thyro-arytenoid muscles
These muscles draw the thyroid cartilage closer
to the arytenoid cartilages thus the vocal
cords are no longer taut and relax.
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The vocalis muscles perform fine, regional
adjustments of tension
Subparts of the vocal ligaments can be tensed and
relaxed.
These muscle fibers attach to the vocal processes
of the arytenoid cartilage and thyroid angle ?
They insert at various places along the vocal
ligaments.
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Muscles that close the laryngeal inlet
Transverse arytenoid ary-epiglottic muscles
These muscles draw the ary-epiglottic folds, the
epiglottis, and arytenoid cartilages together
narrowing the inlet
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Blood supply of larynx
Superior laryngeal a. ? from superior thyroid
a. Inferior laryngeal a. ? from inferior thyroid
a.
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Innervation of the larynx

• VAGUS (CN X)
• Superior laryngeal nerve
• - Internal branch.
• - External branch
• Recurrent laryngeal nerve

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Motor supply to intrinsic muscles of larynx
Recurrent laryngeal nerve supplies all laryngeal
muscles EXCEPT the cricothyroid ? Supplied by
external branch of superior laryngeal nerve.
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Sensory innervation of laryngeal mucosa
Internal branch of superior laryngeal nerve ?
supplies mucosa superior to vocal
folds. Recurrent laryngeal nerve ? Supplies
mucosa of vocal folds and that which is inferior
to the vocal folds.
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Lymphatic drainage of larynx
Lymph vessels follow blood vessels ultimately
draining to deep cervical nodes. Above the vocal
folds ? To superior group of deep cervical nodes.
Below the vocal folds ? To paratracheal and
inferior group of deep cervical nodes.
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Surface anatomy of the larynx
Crico-thyroid membrane
Site of emergency airway
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See any problems?
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Fractured larynx