Transcript Anatomy and Physiology of the Larynx

7/15/2012
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Anatomy and Physiology
of the Larynx
Dr. Supreet Singh Nayyar, AFMC
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• To discuss the basic anatomy of the larynx
• To enumerate the main functions of the larynx
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Objectives
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Laryngeal Cartilages
• Thyroid cartilage
• Cricoid cartilage
• Epiglottis
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• Arytenoid cartilage
• Corniculate cartilage
• Cuneiform cartilage
• Unpaired:
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• Paired
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• Hyaline cartilage
• Largest
• Encloses the larynx
anteriorly and laterally
• Two alae
• Ossification
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Thyroid Cartilage
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Cricoid Cartilage
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 Hyaline cartilage
 Directly below the thyroid
cartilage
 Strongest
 Shape: Signet ring
 Lamina – flat portion
 Only complete annular
support of the larynx
 Articulates w/ Inferior
cornu of the thyroid
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cartilage
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• Fibroelastic cartilage
• Leaf-shaped structure
• Petiole – small narrow
portion of the glottis
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Epiglottis
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• Mostly hyaline cartilage
• Smaller in size
• Responsible for opening and closing of the larynx
• Shape: pyramidal
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Arytenoid Cartilage
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• Vocal process receives the
attachement of the
mobile end of each VC
• Lateral
• Muscular process
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• Anterior
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Arytenoid Cartilage
• Articulation
• Cricoarytenoid joint
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• Fibroelastic
• Cartilages of Santorini
• Small cartilages above the arytenoid and in the aryepiglottic
folds
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Corniculate Cartilages
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• Firboelastic cartilages
• Cartilages of Wrisberg
• Elongated pieces of small yellow elastic cartilage
in the aryepiglottic folds
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Cuneiform Cartilages
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• Cartilago triticea
• Small elastic cartilage in the
lateral thyrohyoid ligament
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Triticeous Cartilage
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Laryngeal Ligaments
• Elastic membrane
• Quadrangular membrane
• Conus elasticus
(cricovocal membrane)
• Median cricothyroid
ligament
• Vocal Ligament
• Thyroepiglottic ligament
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• Thyrohyoid membrane
and ligaments
• Cricothyroid membrane
and ligaments
• Cricotracheal ligament
• Epiglottis
• Intrinsic
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• Extrinsic
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Extrinsic Ligaments
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 pierced on each side by:
1. Superior laryngeal vessels
2. Internal branch of superior
laryngeal nerve
 Median thyrohyoid ligament
– thickened median portion
 Lateral thyrohyoid ligament
– thickened posterior border
- where cartilago triticea is often
found
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 Thyrohyoid membrane
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Extrinsic Ligaments
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• May be pierced for emergency tracheotomy
(cricothyrotomy)
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• Cricothyroid membrane and ligaments
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Extrinsic Ligaments
• Epiglottis
• suspended in position by membranous connections to the hyoid
bone, thyroid cartilage and base of the tongue
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• Attaches the cricoid cartilage to the first attached ring
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• Cricotracheal Ligament
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• Divided into upper and lower parts by the ventricle of the
larynx
• Quadrangular membrane
• Upper part of the elastic membrane
• Boundaries
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• Elastic membrane
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Intrinsic Ligaments
• Epiglottis , arytenoid, corniculate cartilage, false cord
• Forms part of wall between upper pyriform sinus and
laryngeal vestibule
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• Lower part of elastic membrane
• Composed mainly of yellow elastic tissue
• Boundaries
• Inferior: superior border of cricoid cartilage
• Superoanterior: deep surface of angle thyroid cartilage
• Superoposterior: vocal process of arytenoid cartilage
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• Conus elasticus (cricovocal membrane)
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Intrinsic Ligaments
• Median cricothyroid ligament – thickened anteior part
• Vocal Ligament – free upper edge
• Thyroepiglottic ligament
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• Vestibule
• Ventricle
• Subglottic space
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• Divided into 3 parts:
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Cavity of the Larynx
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• Anterior: posterior surface of epiglottis
• Posterior: interval between arytenoid
cartilages
• Lateral: inner surface of aryepiglottic folds
and upper surfaces of the false cord
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• Vestibule – boundaries:
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Cavity of the Larynx
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• Glottis (rima glottidis)
• Abduction: Respiration,
wide and triangular
• Adduction: Phonation, slitlike appearance
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• Ventricle
• Saccule – conical pouch at anterior part
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Cavity of the Larynx
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•
•
•
•
•
•
Boundaries:
Anterior: thyrohyoid membrane
Anteroasuperior: hyoid
Superior: vallecula
Posterior: part of the epiglottis
Lateral: hyoepiglottic ligament
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• Subglottic space
• Preepiglottic space
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Cavity of the Larynx
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Cavity of the Larynx
 True cords





Voice production
Protection of lower respiratory tract
Anteriorly,: angle of thyroid cartilage
Posteriorly: vocal processes of the arytenoid cartilages
Enclose vocal ligament and a major part of the vocalis
muscle
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 Anteriorly: angle of the thyroid cartilage
 Posteriorly: bodies of the arytenoid cartilage
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 False Cords (ventricular bands)
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Laryngeal Joints
• bet. base of the
arytenoid cartilage
and the facet on the
upper border of the
lamina of the cricoid
cartilage
• Two movements:
• Rotation
• Gliding
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• Between inferior
cornu of the thyroid
cartilage and facet on
the cricoid cartilage at
the junction of the
arch and lamina
• Two movements:
• Rotation
• Gliding
• Cricoarytenoid Joint
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• Cricothyroid Joint
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 Depressor group
• Intrinsic Muscles
• Interarytenoid muscle
• Transvers
• Oblique
 Elevator group
 Constrictor muscles
 Pharyngeal muscles
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•
•
•
Post. Cricoarytenoid m.
Lateral cricoarytenoid m.
Thyroarytenoid m.
Cricothyroid m.
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 Extrinsic Muscles
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Laryngeal Muscles
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Depressor
muscles
Origin
Insertion
Action
manubrium of
sternum and
medial end of
clavicle
oblique line of the
thyroid cartilage
depresses/stabilizes
the hyoid bone
Thyrohyoid (C1)
oblique line of the lower border of the
thyroid cartilage hyoid bone
elevates the larynx;
depresses/stabilizes
the hyoid bone
Omohyoid (C2, C3) superior border
of scapula near
the suprascapular
notch
inferior border of
hyoid bone
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Sternohyoid (C2,
C3)
depresses, retracts
and steadies the
hyoid during
swallowing and 26
speaking
Elevator
muscles
Origin
Insertion
Action
inferior mental
spine of mandible
body of hyoid
bone
pulls the hyoid bone
anterosuperiorly, and shortens the
floor of the mouth and widens the
pharynx
Digastrics
(Ant. CN V;
Post. N. VII)
anterior bellydigastric fossa of
mandible,
posterior bellymastoid notch of
temporal bone
intermediate
tendon to body
and greater horn
of hyoid bone
depresses the mandible and raises
the hyoid bone. Also, it steadies
the hyoid bone during swallowing
and speaking
Mylohyoid
(V)
mylohyoid line of
mandible
raphe and body of elevates the hyoid bone, floor of
hyoid bone
the mouth and the tongue during
swallowing and speaking
Stylohyoid
(VII)
styloid process of
body of hyoid
the temporal bone bone
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Geniohyoid
(C1)
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elevates and retracts the hyoid
bone, thereby elongating the floor
of the mouth
Elevator muscles
Origin
Insertion
Action
styloid process
of temporal
bone
posterior and superior elevates the pharynx and
borders of thyroid
larynx and expands the
cartilage with
sides of the pharynx
palatopharyngeus
muscle
Salpingopharyngeus
(pharyngeal plexus)
cartilaginous
part of the
auditory tube
blends with
palatopharyngeus
muscle
Palatopharyngeus
hard palate
and palatine
aponeurosis
lateral wall of pharynx tenses the soft palate and
pulls the walls of the
pharynx superiorly,
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anteriorly and medially
during swallowing
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Stylopharyngeus
(CN IX)
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elevates the pharynx and
larynx and opens the orifice
of the auditory tube during
swallowing
Origin
Insertion
Action
Interarytenoid
m., oblique
(RLN)
muscular process posterior surface of
of the arytenoid
the contralateral
cartilage
arytenoid cartilage,
near its apex
draws arytenoid
cartilages together,
adducting the vocal
folds (closure of
glottis)
Thyroepiglottic
(ELN)
inner surface of the thyroid lateral surface of the epiglottic
cartilage near the laryngeal cartilage
prominence
draws the epiglottic cartilage
downward
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Intrinsic Muscles
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Muscles Controlling the
Laryngeal Inlet
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Muscles Controlling Movements of the Vocal Cords
Insertion
Cricothyroid (ELN)
arch of the cricoid
cartilage
Thyroarytenoid
(vocalis, ILN)
inner surface of the lateral border of the
thyroid cartilage
arytenoid cartilage
Lateral
cricoarytenoid
(ILN)
arch of the cricoid
cartilage
inferior border of the
thyroid cartilage
Action
draws the thyroid
cartilage forward,
lengthening the vocal
ligaments, tenses vocal
cords
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Origin
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Intrinsic Muscles
relaxes and adducts the
vocal folds
muscular process of the Adducts the vocal cords
arytenoid cartilage
by rotating the
arytenoid cartilage
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Origin
Insertion
Action
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Intrinsic Muscles
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Muscles Controlling Movements of the
Vocal Cords
Posterior
cricoarytenoid
(ILN)
posterior surface of muscular process of the Abducts the vocal cords
the lamina of the
arytenoid cartilage
by rotating the
cricoid cartilage
arytenoid cartilage
Interarytenoid m.,
transverse (ILN)
posterior surface of posterior surface of the Closes posterior part of
the arytenoid
contralateral arytenoid rima glottidis by
cartilage
cartilage
approximating
arytenoid cartilages33
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• Ventricles and sacculi
• Posterior surface of epiglottis
• Margins of aryepiglottic folds
• Reinke’s layer of connective tissue: No glands and no lymph
vessels
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• Stratified squamous epith.: over vocal cords and upper part of
vestibule of larynx
• Ciliated columnar epith.: remainder of the cavity
• Mucous glands:
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Mucous Membrane
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Vocal Folds
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Nerve Supply
• Internal branch (sensory) – areas above the glottis
• External branch (motor and sensory)
Motor – Cricothyroid muscle
Sensory – Anterior infraglottic larynx at level of cricothyroid
membrane
• Inferior (recurrent) laryngeal n.
• Motor – all intrinsic laryngeal muscles of SAME side (except
cricothyroid) and interarytenoid muscle of BOTH sides
• Sensory – areas below the glottis
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• Superior laryngeal n.
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• Supplied by Vagus nerve:
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Blood Supply
• Lower Larynx
•
•
•
•
Subclavian artery
Thyrocervical artery
Inferior thyroid artery
Inferior laryngeal
artery
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• External carotid artery
• Superior thyroid artery
• Superior laryngeal
artery
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• Upper Larynx
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Venouos Drainage
• Lower Larynx
• Inferior laryngeal vein
• Inferior thyroid vein
• Innominate vein
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• Superior laryngeal
vein
• Superior thyroid vein
• Internal jugular vein
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• Upper Larynx
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Lymphatic Drainage
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• Supraglottic area
98%: Pedicle Ant. End of aryepiglottic fold -> pass
laterally and leave the larynx through the thyrohyoid
membrane ->Upper deep cervical nodes (bet. Digastric tendon
and omohyoid muscle)
2%: Lower cervical chain or spinal accessory chain
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• Main: Deep Cervical group L.N.
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• Infraglottic area – 3 pedicles
1. Anterior pedicle -> cricothyroid membrane ->
prelaryngeal (Delphian) nodes ->deep inferior cervical nodes
2. 2 Posterolateral pedicles -> cricotracheal membrane ->
paratracheal chain/others to inferior jugular chain
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Lymphatic Drainage
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PHYSIOLOGY
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• Protection
• Respiration
• Phonation
• Fixation of chest
• Closure of glottis
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Basic Functions
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Protection
Closure of the laryngeal inlet
Closure of the glottis
Cessation of respiration
Cough relfex, expulsion of secretions and foreign
bodies
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•
•
•
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• Acts as a sphincter
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• Contraction of superior division of the thyroarytenoid muscles
• Contraction of middle thyroarytenoid fibers
• Contraction of inferior division of thyroarytenoid
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• 3 Sphincteric tiers of airway protection:
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Protection
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 Posterior cricoarytenoids
 Phasic inspiratory abduction
 Synchronous w/respiration
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• Assists in regulation of gaseous exchange with the lung and
maintenance in acid-base balance
• Glottis opens a fraction of a second before air is drawn in by
descent of the diaphragm
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Respiration
 Cricothyroid muscle
 Phasic inspiratory contraction/adduction
 Increases AP diameter of glottic chink
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• Voice produced by
vibration of the vocal
cords
• Fundamental tone
produced at the
larynx
• Modified by
resonating chambers
of the upper
aerodigestive tract
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Phonation in brief
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