Larynx anatomy

Table of Contents
• Functions
• Anatomy
• Subdivisions
• Cartilages
• Vocal Cords
• Muscles
• Nerves
• Vessels
• Special CasesFunctions
• To produce voice
• To protect the airway,
especially during swallowing
• To keep the airway patent
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesAnatomy
• The larynx is located at the point
where the respiratory and
digestive tracts separate.
• The entrance to the larynx, or
laryngeal inlet, is in the anterior
wall of the laryngopharynx.
• Internally, the wall of the larynx is
modified to form the vocal cords.
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesAnatomy
• The larynx lies in the
mid-line of the neck,
deep to the
strap muscles and
partly covered by the
thyroid gland.
• At roughly the C
vertebral level, the
larynx is continuous
with the trachea.
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesSubdivisions
• Vertically, the larynx is
divided into 3 regions:
• 1. Supraglottis –
Includes the epiglottis,
aryepiglottic folds,
false vocal folds,
arytenoids, and
ventricle
• 2. Glottis – true vocal
folds
• 3. Subglottis –below
the true vocal folds to
the inferior border of
the cricoid cartilage
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesCartilages
• Total of 9 cartilages • 3 single cartilages – Thyroid Cartilage (green) – Cricoid (purple) – Epiglottis (light
blue)
• 3 paired cartilages – Arytenoids
(orange)
– Corniculates &
Cuneiforms (black)
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesCartilages
• The hyoid bone
(yellow) and the
cartilages are
collectively
referred to as
the visceral
skeleton of the
neck.
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesThyroid Cartilage
• Thyroid = shield-like
• The largest cartilage
• The two laminae
meet anteriorly at the
superior thyroid
notch (Adam's
apple).
• The inferior horns
articulate with the
cricoid cartilage at
the cricothyroid
joints.
• The thyroid cartilage
suspended from the
hyoid bone by the
thyrohyoid
membrane.
<- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesCricoid
• Cricoid = ringshaped
• The only
complete ring of
cartilage in the
respiratory tract.
• Cricoid pressure
is applied to the
esophagus during
intubation to
prevent gastric
contents from
refluxing into the
airway.
<- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesCricoid
• Anteriorly - a
narrow arch.
• Posteriorly -
enlarges to form
the lamina.
• The cricoid lamina
articulates with
the inferior horns
of the thyroid
cartilage at the
crico-thyroid
joints.
<- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesEpiglottis
• Guards the entrance
of the larynx. It folds
posteriorly over the
opening of the larynx
during swallowing.
• Leaf-shaped, flexible,
elastic cartilage.
• It attaches to the back
of the thyroid cartilage
via the thyroepiglottic
ligament.
• Unlike the other
cartilages, the
epiglottis remains
unossified. <- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesArytenoids
• Paired and
pyramidal in
shape.
• The base rests
on the upper
surface of the
cricoid and forms
the cricoarytenoid
joint.
<- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesArytenoids
• Postero-laterally -
muscular process
• Anteriorly - vocal
process provides
attachment for the
vocal cords.
• Superiorly - apex
<- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesCorniculates & Cuneiforms
• These small cartilages are both in the posterior
part of the aryepiglottic folds
• The corniculates attach to the apices of the
arytenoid cartilages
• The cuneiforms (not shown) do not directly
attach to any cartilages <- Cartilages
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesVocal Cords
Epiglottis
Arytenoids
True
Vocal Cords
False Vocal
Cords
Glottis
Ventricle
Aryepiglottic
Fold
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesTrue Vocal Cords
• Vocal folds (true vocal cords) control
sound production (tone). Each vocal
fold includes:
– Vocal ligament – elastic tissue that
is the thickened medial free edge
of the lateral cricothyroid ligament
(conus elasticus)
– Vocalis muscle – fibres that form
the most medial part of the
thyroarytenoid muscle
<- Photo
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesFalse Vocal Cords
• Vestibular folds (false vocal cords)
extend between the thyroid and
arytenoids.
– Have little to no part in voice
production
– Serve a protective function
• Vestibular folds are the mucous
membrane covering the lower
border of the quadrangular
membrane
<- Photo
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesVentricle
• Between the true vocal
cords and false vocal
cords, on each side, is a
lateral depression, lined by
mucous membrane, known
as the ventricle of the
larynx.
<- Photo
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesGlottis
• Glottis (rima glottidis) -
the opening between
the two true vocal cords
(or vocal folds).
<- Photo
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesLarynx – Sagittal View
Epiglottis
Aryepiglottic
Fold
Arytenoids
True
Vocal Cords
Ventricle
False Vocal
Cords
Thyroid
Cartilage
Cricoid
Conus
Elasticus
Quadrangular
Membrane
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesLarynx – Posterior View
Epiglottis
Aryepiglottic
Fold
Arytenoids
Cricoid Thyroid
Cartilage
Quadrangular
Membrane
Hyoid Bone Thyrohyoid
Membrane
Thyroepiglottic
Ligament
<- Photo
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesQuandrangular Membrane
(In more detail)
• The quadrangular membrane is a
sheet of fibrous connective tissue that
extends from the arytenoids to the
epiglottis.
• The upper border, covered by mucous
membrane, is the aryepiglottic fold.
• The lower border is the vestibular
ligament.
• The latter, together with its covering of
mucous membrane, is the vestibular
fold, or false vocal chord.
<- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesConus Elasticus (In more detail)
• The conus elasticus attaches to
the upper surface of the cricoid
arch.
• Its upper border is the vocal
ligament which extends between
the vocal process of the arytenoid
cartilage and the thyroid lamina.
• The vocal ligament, covered with
mucous membrane, is the vocal
fold or true vocal chord.
• The membrane between the
thyroid cartilage and cricoid is the
cricothyroid membrane. <- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesVocal Cords
Abducted Adducted
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesVocal Cord Abduction & Adduction
• The vocal cords are abducted
during breathing
• The vocal cords are tightly
adducted in straining efforts and
before a cough or sneeze.
• Voice production is the result of
the escape of small amounts of
air between the adducted vocal
cords.
<- Photos
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesPhonation Physiology
• Power source – Lungs & Diaphragm
• Pitch & quality – Larynx
• Articulation – Lips and Tongue
<- Photos
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesMuscles
• The muscles of the larynx are classified
as extrinsic or intrinsic
• Extrinsic laryngeal muscles
– Move the larynx as a whole
– Depress or elevate the hyoid bone & larynx
– Infrahyoid strap muscles (omohyoid, sternohyoid,
sternothyroid, thyrohyoid)– depressors
– Palato-pharyngeus & stylopharyngeus muscles –
elevators
• Intrinsic laryngeal muscles
– Move parts of the larynx
– Control the length/tension and movements of the
vocal folds and may help in the closure of the
laryngeal inlet
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesExtrinsic Muscles
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesIntrinsic Muscles – Posterior View
Epiglottis
Arytenoids
Cricoid
Thyroid
Cartilage
Hyoid Bone
Posterior
Cricoarytenoid
Muscle
Aryepiglottic
Muscle
Interarytenoid
Muscle
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesIntrinsic Muscles
Lateral View from Inside
Arytenoids
Thyroid Cartilage
Cricoid
Aryepiglottic Fold
Quadrangular Membrane
Thyroepiglottic Muscle
Thyroarytenoid Muscle
Lateral Cricoarytenoid
Muscle
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesIntrinsic Muscles
Lateral View from Inside
Thyroid Cartilage
Cricoid
Cricothyroid Muscle
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesPosterior Cricoarytenoid Muscle
• From the posterior surface of
the lamina of the cricoid, its
fibres converge to insert into
the muscular process of the
arytenoid.
• The two posterior
cricoarytenoid muscles abduct
the vocal chords by both
rotating and separating the two
arytenoid cartilages. <- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesInterarytenoid muscle
• Consists of transverse and
oblique fibres which pass
between the two arytenoid
cartilages.
• They adduct the vocal chords
by drawing the two arytenoid
cartilages together.
<- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesAryepiglottic muscle
• This muscle is an
extension of the oblique
interarytenoid muscle
along the
aryepiglottic fold to the
epiglottis.
• It aids in pulling down the
epiglottis over the
laryngeal inlet during
swallowing. <- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesLateral Cricoarytenoid Muscle
• Originates from the upper
margin of the cricoid arch
and inserts into the
muscular process of the
arytenoid.
• It adducts the vocal chord
by rotating the arytenoid
cartilage, so that the vocal
process swings towards the
mid-line. <- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesCricothyroid Muscle
• Passes from the arch of the
cricoid to the inferior margin
and inferior horn of the thyroid
cartilage.
• It acts on the cricothyroid joint,
causing an increase in the
length, and/or tension of the
vocal chords.
• This movement is opposed by
the thyroarytenoid muscle.
<- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesThyroarytenoid Muscle
• Passes between the
arytenoid and thyroid
cartilages, on the lateral
side of the vocal ligament.
• It contracts to shorten the
vocal chord and/or
decrease its tension.
• This movement is opposed
by the cricothyroid muscle.
<- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special Cases• Some detached fibres of
the thyroarytenoid may
extend up to the epiglottis
as the thyroepiglottic
muscle.
• This muscle aids in
depressing the epiglottis
and closing off the larynx
during swallowing.
Thyroepiglottic Muscle
<- Diagram
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesNerves
• The larynx is innervated by branches of the
vagus nerve (CN X).
• Sensory
– For the laryngopharynx, the internal laryngeal
branch of the superior laryngeal nerve
supplies sensation above the vocal chords
(supraglottis/glottis) and the
recurrent laryngeal nerve supplies sensation
below the vocal chords (subglottis).
• Motor
– All intrinsic muscles are supplied by the
recurrent laryngeal nerve, except for the
cricothyroid which is supplied by the external
laryngeal nerve. The cricothyroid muscle
tenses the vocal folds.
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesFunctions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesRecurrent
Laryngeal
Nerve
• LEFT
– Loops around
aortic arch
• RIGHT
– Loops around
subclavian
artery
Functions
Anatomy
Subdivisions
Cartilages
Vocal Cords
Muscles
Nerves
Vessels
Special CasesVessels
• Arteries
– Superior and inferior laryngeal
arteries (from the superior and
inferior thyroid arteries)
accompany the internal and
recurrent laryngeal nerves,
respectively.
• Vein
– Venous drainage is by
corresponding veins.