LARYNX
The larynx constitutes the organ of phonation and forms part of the respiratory tract
Position
•It lies in the median part of the front of the neck, opposite the 3rd, 4th, 5th and 6th cervical vertebrae.
•It extends from the upper border of epiglottis to the lower border of cricoid cartilage
•Its upper end opens into the laryngopharynx by the laryngeal inlet
•Its lower end is continuous with the trachea at the level of the 6th cervical vertebra.
epiglottis
C3
Hyoid bone
C6
Thyroid cartilage
Cricoid cartilage
trachea
Structure of the larynx
The larynx is formed of a number of cartilages joined together by:
• Ligaments
• Membranes
• Muscles
• Synovial joints
epiglottis
Cartilago triticea
Cartilages of the larynx
Single cartilage:
•Thyroid cartilage
•Cricoid cartilage
•Epiglottis
Paired cartilages:
•Arytenoid cartilages
•Corniculate cartilages
•Cuneiform cartilages
Thyroid cartilage
Cuneiform cartilage
Corniculate cartilage
Arytenoid cartilage
Cricoid cartilage
Thyroid cartilage
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The largest laryngeal cartilage
Formed of 2 quadrilateral laminae which are fused anteriorly
Posteriorly, the 2 laminae are separated by a wide gap
The anterior border forms a median projection, the
Superior thyroid notch
Superior horn
laryngeal prominence
• The laminae present a median V-shaped notch, the superior
thyroid notch
• The posterior borders form upward and downward
projections, superior & inferior horns
• The outer surface of each lamina shows an oblique ridge, the
oblique line
• The oblique line extends between two tubercles, the superior
and inferior thyroid tubercles
Thyroid lamina
Laryngeal
prominence
Oblique line
Inferior horn
Thyroid lamina
Superior horn
Superior horn
Superior tubercle
Oblique line
Inferior tubercle
Inferior horn
Laryngeal prominence
Thyroid lamina
Posterior border
Inferior horn
Cricoid cartilage
• Smaller, but thicker than the thyroid cartilage
• Lies below and behind the thyroid cartilage
• It has the shape of a signet ring with a quadrilateral lamina, posteriorly, and a narrow arch, anteriorly
• Its lower border is horizontal
• Its upper border is sloping
Lamina of cricoid
cartilage
Posterior lamina of
cricoid cartilage
Upper border
of cricoid cartilage
Lower border
of cricoid cartilage
Arch of cricoid cartilage
Epiglottis
Median & lateral
• A leaf-shaped lamella of elastic cartilage
Glossoepiglottic folds
• It projects upwards behind the tongue and hyoid bone
• Has an upper broad free end and a lower tapering end
• Anteriorly, it is connected to:
1.The root of the tongue, by the median and lateral glosso-epiglottic folds
2.The hyoid bone, by the hyoepiglottic ligament
3.The inner surface of the thyroid cartilage by the thyroepiglottic ligament
Epiglottis
(posterior view)
Hyoepiglottic ligament
Hyoid bone
Thyroepiglottic
ligament
Thyroid cartilage
Cricoid cartilage
Epiglottis
Arytenoid cartilage
• A pyramid-shaped cartilage, with an apex, base and 3 surfaces:
1. Posterior surface
2. Anterolateral surface
Corniculate cartilage
3. Medial surface
• The apex is directed upwards and articulates with the
Posterior surface
corniculate cartilage
• The base is directed downwards and articulates with
Lateral (muscular)
process
the upper border of the lamina of cricoid cartilage
• The lateral angle of the base projects to form the muscular process
• The anterior angle of the base projects to form the vocal process
Anterior (vocal)
process
Corniculate cartilage
Lamina of
cricoid cartilage
Anterolateral surface
Lateral (muscular)
process
Anterior (vocal)
process
Corniculate cartilage
Posterior surface
Lateral (muscular)
process
Cricoid cartilage
Medial surface
Anterior (vocal)
process
Corniculate cartilage
• A small cartilage on the apex of the arytenoid cartilage
• Enclosed in the aryepiglottic fold forming the
Corniculate cartilage
corniculate tubercle
Cuneiform cartilage
A small nodule enclosed in the aryepiglottic fold forming the cuneiform tubercle
Aryepiglottic fold
Cuneiform tubercle
Corniculate tubercle
Joints of the larynx
Cricothyroid joints:
• One on each side
• A synovial joint between the inferior horn of the
thyroid cartilage and the side of the cricoid cartilage
Cricoarytenoid joints:
• One on each side
• A synovial joint between the base of arytenoid
cartilage and upper border of the cricoid lamina
Arycorniculate joints:
• One on each side
• A joint between the apex of the arytenoid
cartilage and the corniculate cartilage
Arycorniculate
joint
Cricothyroid joint
Cricoarytenoid joint
Cricothyroid joint
Membranes and ligaments of the larynx
Thyrohyoid membrane:
• Extends from the upper border of thyroid cartilage to the upper border of posterior surface of hyoid bone
• Separated from the posterior surface of hyoid bone by the hyoid bursa
• The median part of the membrane is thickened to form the median thyrohyoid ligament
• The membrane is pierced by the superior laryngeal vessels and the internal laryngeal nerve.
• The posterior border is thickened to form the lateral thyrohyoid ligament
• The lateral thyrohyoid ligament contains a cartilage nodule called the cartilago triticea.
Lateral thyrohyoid ligament
Cartilago triticea
Foramen for sup laryngeal
vessels & internal laryngeal n.
Thyrohyoid membrane
Median thyrohoid ligament
Cricothyroid ligament: (conus elasticus)
• An elastic band which lies below and on the inner aspect of the thyroid cartilage
• It is connected to:
• Thyroid cartilage
• Cricoid cartilage
• Arytenoid cartilage
• Two parts of the ligament can be recognized:
Median cricothyroid ligament: the anterior thickened part of the ligament which connects the adjacent
borders of the cricoid and thyroid cartilages.
- The ligament is overlapped by the cricothyroid muscle.
Median
cricothyroid ligament
Median
cricothyroid ligament
Cricothyroid muscle
Lateral cricothyroid ligament (crico-vocal membrane)
this ligament is attached inferiorly to the upper border of cricoid cartilage
superiorly, it has 2 attachments:
to the inner surface of thyroid cartilage, anteriorly
to the vocal process of arytenoid cartilage, posteriorly
The free upper border of the crico-vocal membrane is called the Vocal Ligament
“The vocal ligament is attached to the inner surface of thyroid cartilage
(anteriorly) and to the vocal process of the arytenoid cartilage (posteriorly)”
Thyroid cartilage
Thyrohyoid ligament
Median cricothyroid ligament
Vocal ligaments
Lateral cricothyroid ligament
Vocal process
Upper border of cricoid cartilage
Vocal ligament
Arytenoid cartilage
Posteroir lamina
of cricoid cartilage
Vocal process
Cricoid cartilage
Other ligaments of the larynx
•Hyo-epiglottic ligament: connects the anterior surface of epiglottis to the hyoid bone
•Thyro-epiglottic ligament: connects the lower end of the epiglottis to the inner surface of thyroid cartilage
•Crico-tracheal ligament: connects the lower border of the cricoid cartilage to the first ring of trachea
•Ligaments of the joints
Epiglottis
Hyo-epiglottic ligament
Hyoid bone
Thyro-epiglottic ligament
Thyroid cartilage
Cricoid cartilage
Interior of the larynx
Inlet of the larynx:
- The opening of communication between the pharynx and larynx
- The laryngeal inlet is directed upwards and backwards
Boundaries of the inlet:
• Upper border of epiglottis anteriorly
• Aryepiglottic folds on both sides
• Mucous membrane between the arytenoid cartilages posteriorly
Inlet of the larynx
Aryepiglottic fold:
• A fold of mucosa extending between the apex of
arytenoid cartilage and the side of epiglottis
• It encloses the aryepiglottic muscle, cuneiform
and corniculate cartilages
Aryepiglottic fold
Cuneiform tubercle
Aryepiglottic muscle
Corniculate tubercle
Vocal fold:
• A fold of mucous membrane extending from
the inner surface of thyroid cartilage to the
vocal process of arytenoid cartilage
• The folds enclose the vocal ligaments (upper
free border of lateral cricothyroid ligaments)
• The fissure between the 2 vocal folds is
called rima glottidis
Vestibular fold:
epiglottis
Aryepiglottic fold
Vestibular fold
Sinus of
larynx
Thyroid cartilage
Medial surface of
arytendoid cartilage
Cricoid
cartilage
• A fold of mucous membrane extending from the inner surface of
thyroid cartilage to the anterolateral surface of arytenoid cartilage
• It encloses a fibrous band called the vestibular ligament
Vocal process
Vocal fold
Sinus of the larynx:
• A recess between the vestibular and vocal folds
Vestibule of the larynx:
epiglottis
• The upper part of the laryngeal cavity, between
the inlet and the vestibular folds
Mucosa of the larynx:
• Lined by pseudostratified columnar ciliated epitheliuum
containing goblet cells and mucous glands
• The vocal folds are lined by non-keratinizing stratified
squamous epithelium without submucosa or blood vessels
• The vocal folds appear pearly white during laryngoscopy
Thyroid
cartilage
Vocal
ligament
Vocal
process
Arytenoid
cartilage
Rima glottidis (glottis)
The fissure between the two vocal folds anteriorly (inter-membranous part)
and the two arytenoid cartilages posteriorly (inter-cartilagenous part)
Vocal process
Intermembranous part
Rima glottidis (glottis)
Intercartilagenous part
Arytenoid cartilage
Muscles of the larynx
Extrinsic muscles of the larynx
Intrinsic muscles of the larynx
• Elevators of the larynx
• Stylopharyngeus
• Palatopharyngeus
• Salpingopharyngeus
• Depressors of the larynx
• Sternothyroid
• Thyrohyoid
• Are muscles which connect the laryngeal cartilages together
• All are paired EXCEPT the transverse arytenoid
• They include:
• Cricothyroid
posterior
• Cricoarytenoid
lateral
• Ary-epiglottic
transverse
• Arytenoid
• Thyro-arytenoid
• Thyro-epiglottic
• Vocalis
oblique
Muscles of the larynx
Cricothyroid:
The only intrinsic muscle seen on the outside of the larynx
The only muscle of the larynx supplied by the external laryngeal nerve
O: outer aspect of the arch of cricoid
I: inferior horn and lower border of thyroid cartilage
A: a tensor of the vocal fold (lengthens the vocal fold)
N: external laryngeal nerve
Cricothyroid m.
Vertical part
Action of cricothyroid
Lengthening (tightening) the vocal cords
Cricothyroid m.
oblique part
Posterior Crico-arytenoid:
Lateral Crico-arytenoid:
O: posterior surface of cricoid lamina
I: muscular process of arytenoid cartilage
A: abduction of vocal cords
O: upper border of arch of cricoid cartilage
I: muscular process of arytenoid cartilage
A: adduction of vocal cords
Lateral cricoarytenoid
Posterior
cricoarytenoid
Cricothyroid
Posterior cricoarytenoid
Cricoid lamina
Lateral cricoarytenoid
Muscular process
Vocal process
Cricoid arch
Cricothyroid
Thyroid
cartilage
Vocal cords
Action of posterior cricoarytenoid
Abduction of vocal cords
Action of lateral cricoarytenoid
Adduction of vocal cords
MOVEMENT OF VOCAL CORDS
Adduction of vocal cords:
Abduction of vocal cords:
•Lateral cricoarytenoid
•Transverse arytenoid (also closes the rima glottidis)
•Posterior cricoarytenoid
Closure of laryngeal inlet:
Widening of laryngeal inlet:
•Oblique arytenoid
•Aryepiglottic
•Thyroepiglottic
Relaxation of vocal ligaments:
Tension of vocal ligaments:
•Thyroarytenoid
•Vocalis
•Cricothyroid
Closure of rima glottidis:
•Transverse arytenoid
Normal larynx during inspiration
Normal larynx during phonation
Functions of the larynx:
• Respiratory function: it forms part of the respiratory airway
• Phonation: (production of sound waves)
• Raising the intra-abdominal pressure: by closing the rima
labour)
glottidis during expiration (ex. during
Arterial supply of the larynx:
• Superior laryngeal artery: from the superior thyroid artery
(it pierces the thyrohoid membrane with the internal laryngeal nerve)
• Inferior laryngeal artery: from the inferior thyroid artery
(it ascends deep to the inferior pharyngeal constrictor with the recurrent laryngeal nerve)
Venous drainage of the larynx:
• Superior laryngeal vein: drains into the superior thyroid vein
• Inferior laryngeal vein: drains into the inferior thyroid vein
Nerve supply of the larynx:
• Superior laryngeal nerve (from vagus), Divides into:
• External laryngeal: supplies the cricothyroid m.
• Internal laryngeal: supplies the mucous membrane above the level of the vocal folds
• Recurrent laryngeal nerve (from vagus), Divides into motor and sensory branches
• The motor branch supplies ALL intrinsic muscles of the larynx (except cricothyroid)
• The sensory branch supplies the mucous membrane below the level of the vocal folds