The
larynx
The Larynx
 The larynx constitutes the organ of phonation
and forms a protective sphincter to the
respiratory system.
 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 sixth cervical vertebra.
The Larynx
 The larynx is formed by a cartilaginous skeleton
attached together by joints and ligaments and moved
by muscles and all are covered by mucous
membrane.
 Laryngeal cartilages:
A. Single:
1. Thyroid cartilage.
2. Cricoid cartilage.
3. Epiglottis cartilage.
B. Paired:
1. Arytenoid cartilages.
2. Corniculate cartilages.
3. Cuneiform cartilages.
Thyroid Cartilage
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
laryngeal prominence.
The laminae present a median V-shaped notch, the
superior thyroid notch.
The posterior borders form upward and downward
projections, superior and 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.
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.
Epiglottis Cartilage
A leaf-shaped lamella of elastic cartilage.
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:
– The root of the tongue, by the median and lateral glossoepiglottic folds.
– The hyoid bone, by the hyoepiglottic ligament.
– The inner surface of the thyroid cartilage by the
thyroepiglottic ligament.
Arytenoid Cartilage
A pyramidal-shaped cartilage, with an apex, base and 3
surfaces:
– Posterior surface.
– Anterolateral surface.
– Medial surface.
The apex is directed upwards and articulates with the
corniculate cartilage.
The base is directed downwards and articulates with the
upper border of the lamina of cricoid cartilage.
The lateral angle of the base projects and forms the
muscular process.
The anterior angle of the base projects to form the vocal
process.
Corniculate Cartilage

A small cartilage on the apex of the arytenoid
cartilage
 Enclosed in the aryepiglottic fold forming the
corniculate tubercle
Cuneiform Cartilage
 A small nodule enclosed in the aryepiglottic
fold forming the cuneiform 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 lamina of cricoid
cartilage.
Arycorniculate joints:
– One on each side.
– A joint between the apex of the arytenoid cartilage
and the corniculate cartilage.
Membranes and ligaments
1.
2.
3.
4.
5.
6.
7.
8.
9.
Thyrohyoid membrane and ligaments.
Fibroelastic membrane.
Quadrangular membrane.
Vestibular ligament.
Cricothyroid ligament (conus elasticus).
Vocal ligament.
Hyoepiglottic ligament.
Thyroepiglottic ligament.
Cricotracheal ligament.
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 posterior border is thickened to form the lateral
thyrohyoid ligament.
The membrane is pierced by the superior laryngeal
vessels and the internal laryngeal nerve.
The lateral thyrohyoid ligament contains a cartilage
nodule called the cartilago triticea.
Fibroelastic membrane
Its upper part is called quadrangular membrane and its
lower parts is called cricothyroid ligament (conus
elasticus).
The quadrangular membrane:
– It extends between the lateral border of the epiglottis
and the arytenoid cartilage.
– Its lower free border forms the vestibular ligament.
The 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
and 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.
2. 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.
– So, the vocal ligament is attached to the inner surface
of thyroid cartilage (anteriorly) and to the vocal process
of the arytenoid cartilage (posteriorly).
1.
Other ligaments
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.
Laryngeal Inlet
The opening of communication between the pharynx
and larynx.
It is directed upwards and backwards
Boundaries:
– Upper border of epiglottis anteriorly.
– Aryepiglottic folds on both sides.
– Mucous membrane between the arytenoid
cartilages posteriorly.
Aryepiglottic fold:
– Is 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.
Laryngeal
Cavity
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 border of
lateral cricothyroid ligaments).
– The fissure between the 2 vocal folds is called the rima
glottidis.
Vestibular fold:
– 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.
Sinus of the larynx:
– A recess between the vestibular and vocal folds
Vestibule of the larynx:
– The part of the cavity between the inlet and the vestibular
folds
Muscles
of
the
larynx
Extrinsic muscle:
–
Elevators:
Digastric, stylohyoid, mylohyoid, geniohyoid,
stylopharyngeus, salpingopharyngeus and palatopharyngeus.
– Depressors:
Sternothyroid, sternohyoid, omohyoid muscles and the elastic
recoil of the trachea.
Intrinsic muscles:
– Acting on the laryngeal inlet:
Narrowing: oblique arytenoid and aryepiglottic muscles.
Widening: thyroepiglottic muscle.
– Acting on the vocal cords:
Sphincteric action:
– Adduction: lateral cricoarytenoid & transverse arytenoid.
– Abduction: posterior cricoarytenoid.
Change in length and tension:
– Elongation and tension: cricothyroid.
– Shortening and relaxation: thyroarytenoid and vocalis.
Oblique arytenoid Muscle
Origin: from the back of the muscular
process of the arytenoid cartilage.
Insertion: into the apex of the opposite
arytenoid cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: narrowing of the laryngeal inlet
by bringing the two aryepiglottic folds
together.
Aryepiglottic Muscle
Origin: from the apex of the arytenoid
cartilage as a continuation of the oblique
arytenoid muscle.
Insertion: into the side of the epiglottis
cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: narrowing of the laryngeal inlet
by shortening the aryepiglottic fold.
Thyroepiglottic Muscle
Origin: from the inner surface of the
thyroid cartilage.
Insertion: into the side of the epiglottis
cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: widening of the laryngeal inlet.
Lateral Cricoarytenoid Muscle
Origin: from the upper border of the arch
of cricoid cartilage.
Insertion: into the muscular process of
the arytenoid cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: Adduction of the vocal cords by
rotation of the arytenoid cartilage.
Transverse Arytenoid Muscle
Origin: from the back and medial surface
of the arytenoid cartilage.
Insertion: into the back and medial
surface of the opposite arytenoid
cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: Adduction of the vocal cords by
approximating the arytenoid cartilages.
Posterior Cricoarytenoid Muscle
Origin: from the posterior surface of the
lamina of the cricoid cartilage.
Insertion: into the muscular process of
the arytenoid cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: Abduction of the vocal cords by
rotating the arytenoid cartilage.
Thyroarytenoid Muscle
Origin: from the inner surface of thyroid
cartilage lateral to the cricothyroid
ligament.
Insertion: into the antero-lateral surface
of arytenoid cartilage.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve).
Action: shortening and relaxation of the
vocal fold.
Vocalis Muscle
Origin: deep fibers of thyroarytenoid.
Insertion: into the vocal process of
arytenoid cartilage and vocal ligament.
Nerve supply: recurrent laryngeal nerve
(branch of vagus nerve.
Action: shortening and relaxation of the
vocal fold.
Nerve Supply of the Larynx
1. Superior laryngeal nerve (from vagus nerve)
divides into:
A. External laryngeal nerve (motor): supplies the
cricothyroid muscle.
B. Internal laryngeal nerve (sensory): supplies
the mucous membrane above the level of the
vocal folds.
2. Recurrent laryngeal nerve (from vagus nerve)
divides into motor and sensory branches:
– The motor branch supplies ALL intrinsic muscles
of the larynx (except cricothyroid muscle).
– The sensory branch supplies the mucous
membrane below the level of the vocal folds.
Blood supply of the larynx
Arterial supply of the larynx:
1. Superior laryngeal artery (from superior
thyroid artery from external carotid artery).
2. Inferior laryngeal artery (from inferior thyroid
artery from thyrocervical trunk from 1st part
of subclavian artery).
Lymph drainage of the larynx
To the deep cervical lymph nodes.
Clinical Points of the Larynx
1. Injury of the external laryngeal nerve:
Paralysis of the cricothyroid muscle which
affects the voice (weakness) with no effect
on air pathway.
2. Injury of the recurrent laryngeal nerve:
1. Unilateral complete section: the affected
vocal cord will be between adduction and
abduction (cadaveric position). The other
cord will compensate and crosses to the
other side and this will not affect the voice
or respiration
Clinical Points of the Larynx
2. Bilateral complete section: both vocal
cords will be between adduction and
abduction (cadaveric position). The voice
will be lost and the respiration is slightly
affected.
3. Unilateral partial section: the affected
side will show paralysis of the abductor
muscle (posterior cricoarytenoid), the
affected vocal cord will stay in adduction
position, the other cord will compensate.
Clinical Points of the Larynx
4. Bilateral partial section: a severe
condition because both vocal cords will
be paralyzed in adducted position). The
patient will suffer from stridor and
asphyxia and tracheostomy or
cricothyriodotomy is life saving process.