The Larynx and Phonation

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The Larynx and Phonation
GEMP 2006 Avinash Bharadwaj
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Location and Extent

• Air and food passages

• Extent

• Note relationship with
• Tongue
• Hyoid bone
• Pharynx
• Vertebral column

H
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The Skeletal Basis

• The thyroid cartilage

• Lamina

• Notch and laryngeal prominence

• Superior and inferior horns

• The cricoid cartilage

• Lamina

• Arch

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The Skeletal Basis

• Arytenoids
• (With corniculate)

• Epiglottis

• Cuneiform and trititial

• Note articular facets on the cricoid

• Vocal and muscular processes of the arytenoid

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The Assembly
A-L
L
P
A-L
L
P

• Note the positions of the cartilages, joints and
  the hyoid bone

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Crico-Thyroid Connections
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The Lining

• Vestibule

• Vestibular folds

• Vocal folds

• Infraglottic space

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The Muscles

• Extrinsic
• Muscles that move the entire larynx
• e.g. three longitudinal pharyngeal muscles.
• Intrinsic
• Muscles controlling the inlet
• Muscles altering cord position
• Muscles altering cord length and tension

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Muscles Lateral View
Thyro-epiglotticus
Cricoarytenoids

• Lateral

• Posterior

Cricothyroid
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Muscles Posterior View
Oblique arytenoid aryepiglotticus
Transverse arytenoid (hidden)
Posterior cricoarytenoid
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Muscles Acting on the Inlet

• Narrowing of the inlet
• Aryepiglotticus shortens aryepiglottic folds
• Transverse and oblique arytenoids - bring the
  arytenoid cartilages together.
• Opening of the inlet
• Thyroepiglotticus Pulls epiglottis anteriorly.

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Size of the Glottis
Abduction
Adduction
Rotation of Arytenoids
Lateral movements of arytenoids
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The Muscles
Abduction by rotation of arytenoids
If the muscular processes move as shown (blue
arrows), the vocal processes move laterally (red
arrows).
Such a force is exerted by the upper (horizontal)
fibres of the posterior cricoarytenoid.
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The Muscles
Abduction by lateral movement of arytenoids
The posterior cricoarytenoid is one muscle
that can abduct the vocal cords by both
possible mechanisms.
The arytenoid sits on the shoulder of the
cricoid lamina. A downward pull, exerted by the
vertical fibres of the posterior cricoarytenoid
therefore causes the arytenoid to slide down
the shoulder, thus moving it laterally.
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It takes two muscles to adduct the cords.
Adduction
Transverse arytenoid is the muscle that brings
them together! (Aided by the oblique arytenoids)
The lateral cricoarytenoid pulls the muscular
process forwards consequent rotation of the
arytenoid adducts the cords.
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Vocal Cords Elongation and Stretch
The muscle Cricothyroid
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Vocal Cords Shortening
The thyroarytenoid muscle
Differential stretching / elongation of segments
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Functional Implications

• During deglutition
• Airflow regulation
• Phonation
• Phonation and speech