Anatomy of Larynx

1. ANATOMY OF LARYNX
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PRESENTER :- DR K.SREENIVAS NAIK,JUNIOR RESIDENT.
MODERATOR:- DR K. SANTHAIAH Sir. Professor, Dept. of ENT, ASRAM, ELURU.

2. INTRODUCTION

3. Larynx present centrally in the neck extending from laryngeal inlet
to inferior border of cricoid cartilage.
It lies in front of 3rd to 6th cervical vertebrae, being little higher in
women than men.
Consists of a framework of 9 cartilages connected to each other by
ligaments and membranes as well as intrinsic and extrinsic muscles.
It is lined by mucous membrane that is continuous above with pharynx and
below trachea.
Larynx is suspended from hyoid bone by muscles and ligaments.

4. THE LARYNX is divided
into
SUPRAGLOTTIS
GLOTTIS
SUBGLOTTIS
by false and true vocal
folds.

5. SUPRAGLOTTIS- starts at epiglottis and
aryepiglottic folds. Lower border is the horizontal
line drawn through the apex of laryngeal ventricle.
GLOTTIS- above line – includes the vocal cords ,
ant commisure, post. Commisure.
lower limit is a line drawn 1 cm below the free
edge of the vocal folds.
SUBGLOTTIS- area below the above mentioned
line upto the lower border of the cricoid.

6. EMBRIOLOGY OF LARYNX

7. During the fourth week of embryonic development, the
tracheobronchial diverticulum appears in the ventral wall of
the primitive pharynx just below the hypobranchial eminence.
edges of this groove form the oesophagotracheal septum
which fuses caudally, leaving a slit-like aperture cranially into
the pharynx
The cranial end of the tube forms the larynx and trachea and
the caudal end the bronchi and lungs.
These tubes of endoderm grow into the mesenchyme from
which the connective tissue, cartilage, nonstriated muscle and
vasculature of the bronchi and lungs develop.
On both sides of the tracheobronchial diverticulum Arytenoid
swellings appear and s grow upwards and deepen to produce
the aryepiglottic folds

8. hypobranchial eminence becomes the epiglottis
glottis forms just above the level of the primitive aperture
The thyroid cartilage develops from the fourth pharyngeal arch.
cricoid cartilage and the cartilages of the trachea develop from the sixth arch
during the sixth week
The mesoderm of each pharyngeal arch differentiates into the cartilage,
muscle and vascular structures of that arch
Each arch receives an afferent and efferent nerve supply for the skin, muscles
and endodermal lining of that arch
fourth and sixth arches are supplied by the superior and recurrent laryngeal
nerve branches of the vagus which supply the larynx

9. FRAMEWORK OF LARYNX

10. 1. HYOID BONE
2. Unpaired cartilages
a) Epiglottis
b) Thyroid cartilage
c) Cricoid cartilage
3. Paired cartilages
a) Arytenoid cartilages
b) Cuniform cartilages
c) Corniculate cartilages

11. HYOID BONE
U shaped bone
Suspended by ligaments and muscles from bony structure of
skull base and mandible.
Provide attachment to extrinsic muscle of the larynx , thereby
suspending the larynx in the neck.
Hyoid bone consists of
1) body anteriorly
2) greater cornua – projections backwards from body
3) Lessor cornua – attached to upper aspect of body
laterally either by fibrous band or synovial joint.

12. EPIGLOTTIS
It is thin leaf like elastic fibrocartilage
It is attached to the thyroid cartilage just below the thyroid notch in the midline by
THYROEPIGLOTTIC LIGAMENT and to the hyoid bone anteriorly by HYOEPIGLOTTIC
LIGAMENT.
The ANTERIOR (LINGUAL) SURFACE is covered with mucous membrane which is
reflected onto the tongue and lateral wall of pharynx, forming a median
glossoepiglottic fold and two lateral glossoepiglottic folds.
Depression formed on either side of the median glossoepiglottic fold is the
vallecula.
The POSTERIOR (LARYNGEAL) SURFACE is indented by numerous small pits
into which mucus glands project.

13. THYROID CARTILAGE
Composed of two laminae fused in medline anteriorly
forming the laryngeal prominence (Adam’s Apple) .
Angle of fusion is 90 in men and 120 in female.
Posterior border of each lamina forms superior and
inferior horn.
Superior horn – long and narrow curved upwards,
backwards medially. Lateral thyroid ligament is
attached to it.
Inferior horn – shorter thicker curves downwards and
medially. Has facet to articulate with cricoid cartilage

14. External surface of each lamina
has an oblique line
curves downwards from superior
thyroid tubercle to inferior
thyroid tubercle
This line marks the attachment of
THYROHYOID,
STERNOTHYROID &
INF. CONSTRICTOR MUSCLES

15. On the inner aspect – below the thyroid notch in the midline
THYROEPIGLOTTIC LIGAMENT is attached and below this and
on each side of midline VESTIBULAR and VOCAL LIGAMENTS,
THYROARYTENOID ,THYROEPIGLOTTIC and VOCALIS muscles
are attached.
Superior border – gives attachment to
thyrohyoid ligament
Fusion of anterior ends of two vocal ligaments
produce anterior commissure tendon.
Inferior border of each lamina –gives
attachment to the cricothyroid ligament.

16. CRICOID CARTILAGE
• Only complete cartilaginous ring in the airway.
• Forms the inferior part of the anterior and lateral walls and most of the posterior part
of the larynx
• Has an arch anteriorly and lamina posteriorly with facets for articulation with arytenoid
cartilage and thyroid cartilage.
• A vertical ridge in midline of lamina give attachment to longitudinal muscle of the
esophagus and shallow concavity on either side to posterior cricoarytenoid muscle.

17. The shallow concavity
on either side of the
ridge give rise to the
lt and rt posterior
cricothyroid muscles.
The cricoarytenoid joint together
with an associated functional PCA
muscle regarded as a key
functional unit of the larynx,
facilitating vocal fold motility to
ensure a patent airway when
abducted and airway protection
when adducted.

18. The entire inner surface of the
cricoid cartilage is lined with mucous
membrane. The luminal mucosa is at
risk of necrosis and circumferential
scarring, which results in
SUBGLOTTIC STENOSIS

19. ARYTENOID CARTILAGES
• Each is an irregular three-sided pyramid with
a forward projection – Vocal process and
lateral projection-Medial process.
• Vocal process – attachment to vocal folds
• Medial process – gives attachments to
posterior and lateral cricoarytenoid muscles.
• APEX- curved backwards and medially and
articulates with the corniculate cartilage
which sits on top it.
• BASE – concave and articulate with the
upper border of the cricoid lamina. This is a
SYNOVIAL joint with lax capsular ligament
allowing both rotatory movements and
medial and lateral gliding movements.

20. Antero lateral surface – irregular and divided by a crust into
upper triangular fossa( fovea triangularis) gives attachment
to vestibular ligament and lower is oblong (fovea oblonga),
and vocalis and lateral cricoarytenoid are attached to it.
Medial surface- covered by mucous membrane, form lateral
boundary of rima glottis.
Posterior surface- covered entirely by transverse arytenoid
muscle.

21. CORNICULATE CARTILAGES (of Santorini)
They are two small conical nodules of elastic fibrocartilage
and articulate through a synovial joint with the apices of
the arytenoid cartilages.
They are situated in the posterior part of the aryepiglottic
fold.
CUNEIFORM CARTILAGES (of Wisberg)
two - small, fibroelastic cartilage, one in each free margin
of the aryepiglottic fold.
Their function unknown. They may act to provide
structural rigidity to the aryepiglottic folds somewhat like
curtain weights.

22. JOINTS
CRICOTHYROID JOINT:-
The joints between the inferior cornua of the thyroid cartilage and the sides of
the cricoid cartilage are synovial
primary movement at the joint is rotation around a transverse axis that passes
transversely through both cricothyroid joints.
The effect of this rotation is to move the cricoid and thyroid cartilages relative to
one another in such a way as to bring together or approximate the lamina of the
thyroid cartilage and the arch of the cricoid cartilage (‘closing the visor’).
these movements is to lengthen the vocal folds, also increase vocal fold tension.

23. CRICOARYTENOID JOINT
 The cricoarytenoid joints are a pair of synovial joints between
the facets on the lateral parts of the upper border of the
lamina of the cricoid cartilage and the bases of the arytenoids.
 Two movements occur at this joint.
 The first is rotation of the arytenoid cartilages at right angles
to the long axis of the cricoid facet (dorso-medio-cranial to
ventrolatero-caudal), which, because of its obliquity, causes
each vocal process to swing laterally or medially, thereby
increasing or decreasing the width of the rima glottidis.
 referred to as a rocking movement of the arytenoid cartilages
 2) There is also a gliding movement,
 The movements of gliding and rotation are associated, i.e.
medial gliding occurs with medial rotation and lateral gliding
with lateral rotation, resulting in adduction or abduction of
the vocal folds, respectively

24. ARYTENOCORNICULATE
JOINTS
Synovial or cartilaginous
joints link the arytenoid
and corniculate cartilages.

25. Ligaments &
Membranes

26. EXTRINSIC LIGAMENTS
connect the laryngeal cartilages to the hyoid above and trachea below
SUPERIORLY – THYROHYOID MEMBRANE
The thyrohyoid membrane is a broad, fibroelastic layer attached
below to the superior border of the thyroid cartilage lamina
and the front of its superior cornua, and above to the superior
margin of the body and greater cornua of the hyoid

27. The membrane is reinforced by fibrous tissue
in the midline as the median thyrohyoid
ligament and posteriorly as the lateral
thyrohyoid ligament
The ligaments has a small nodule of cartilage,
the cartilago triticea. It is pierced by the
internal branch of the superior laryngeal
nerve and by the superior laryngeal vessels.
INFERIORLY - cricotracheal ligament unites
the lower border of the cricoid with the first
tracheal ring.

28. INTRINSIC LIGAMENTS
Connects the laryngeal cartilages together, strengthen the
capsule of the intercartilaginous joints.
Divided into an upper and lower part by the laryngeal
ventricle.
UPPER- The upper quadrilateral membrane extends between
the lateral border of the epiglottis and the arytenoid
cartilages.
The upper margin forms the framework of the aryepiglottic
fold and the lower margin is thickened to form the vestibular
ligament underlying the vestibular fold (false vocal fold).

29. LOWER – called cricovocal ligament, cricothyroid
ligament or conus elasticus.
Attached -below -to upper border of the cricoid
cartilage ,
above - it is stretched between the inner surface of
the midpoint of the laryngeal prominence of the
thyroid cartilage anteriorly and the vocal process of
the arytenoid behind.
The free upper border of this membrane
constitutes the vocal ligament the framework of the
(true) vocal fold.

30. LARYNGEAL CAVITY
 Extends from laryngeal inlet to lower border of the
cricoid cartilage
 Fissure between the vestibular folds called rima
vestibuli
 Fissure between the vocal folds called rima glottides
 Divided into three parts:
 Supraglottic part, the part above the
vestibular folds, is called the vestibule
 The part between the vestibular & the vocal
folds, is called the ventricle
 Infraglottic part, the part below the vocal
folds

31.  Laryngeal inlet
 Triangular aperture between larynx and pharynx
 Bounded – superiorly – free edge of epigliottis
on each side – aryepiglottic folds
Posteriorly – mucous membrane between the
two aryepiglottic cartilages.
 Aryepiglottic fold
contains ligamentous and muscular fibres.
 The ligamentous fibres represent the free upper border of
the quadrangular membrane.
 The muscle fibres are continuations of the oblique
arytenoids
 Superior vestibule
 Lies between the inlet of larynx to the level of vestibular
folds.

32.  wide above, narrow below, and higher anteriorly
than posteriorly
 anterior wall is formed by the posterior surface
of the epiglottis
 lateral walls formed by the medial surfaces of
the aryepiglottic folds.
 The posterior wall consists of the interarytenoid
mucosa above the ventricular folds.
 middle part of the laryngeal cavity - is the
smallest, and extends from the rima vestibuli
above to the rima glottidis below. On each side
it contains the vestibular folds, the ventricle and
the saccule of the larynx.

33. Vestibular folds and ligaments
The narrow vestibular ligament represents the thickened lower
border of the quadrangular membrane .
It is fixed in front to the thyroid angle below the epiglottic
cartilage and behind to the anterolateral surface of the arytenoid
cartilage above its vocal process.
With its covering of mucosa, it is termed the vestibular (ventricular
or false vocal) fold
The laryngeal ventricle (also known as the laryngeal sinus) is a slit
between the vestibular folds above and the true vocal folds below

34. Saccule of the larynx
The saccule is a pouch of variable size
that ascends forwards from the anterior
end of the ventricle, between the
vestibular fold and thyroid cartilage.
the saccule, expressing its secretion on
to the vocal cords, which lack glands, to
lubricate and protect them against
desiccation and infection.

35. VOCAL CORDS AND LIGAMENTS
vocal folds are concerned with sound production
The free thickened upper edge of the conus elasticus
forms the vocal ligament
stretches back on either side from the midlevel of the
thyroid angle to the vocal processes of the arytenoids.
When covered by mucosa called vocal cords.
The vocal folds lie on either side of a fissure, the rima
glottidis, and form the anterolateral three-fifths of its
edges.
The posterior two-fifths of the edges of the rima glottidis
are formed by the vocal processes of the arytenoid
cartilages.

36. Each fold is a layered structure consisting of a superficial layer of
nonkeratinizing, stratified squamous epithelium, beneath which
is the lamina propria.
This has three distinct layers. The superficial layer (Reinke’s space)
contains a fibrous substance with similar characteristics to gelatin.
The intermediate layer contains elastic fibres and the deep layer
collagen fibres.
The intermediate and deep layers make up the vocal ligament.

37. The vocalis muscle, which forms the main body of the vocal fold, lies lateral and
deep.
The point at which the vocal ligaments attach to the thyroid cartilage is known as
Broyles ligament;
it contains blood vessels and lymphatics, and therefore represents a potential
route for the escape of malignant tumours from the larynx.
This is a very significant anatomical escape pathway for primary tumours arising
on the vocal cord.

38. INFRAGLOTTIC CAVITY
extends from the vocal cords to
the lower border of the cricoid
and is continuous with the
trachea
Its walls are lined by respiratory
mucosa, and are supported by
the cricothyroid ligament above
and the cricoid cartilage below

39. MUSCLES OF LARYNX
Open and close the glottis
1) Posterior cricoarytenoid
2) Lateral cricoarytenoid
3) Transverse arytenoids – unpaired
4) Oblique arytenoids – paired
Control the tension of the vocal folds
1) Thyroarytenoid (vocalis)
2) Cricothyroid
Alter the shape of laryngeal inlet
1)Aryepiglotticus
2)Thyroepiglotticus

40. OBLIQUE ARYTENOID(PAIRED)
 Origin:-
 Posterior aspect of the muscular
process (superficial to the transverse
arytenoid)
 Insertion:-
 Apex of the other arytenoid.
 Vascular supply:-
 Oblique arytenoid receives its blood
supply from the laryngeal branches of
the superior and inferior thyroid
arteries.

41. OBLIQUE ARYTENOID(PAIRED)
 Innervation :-
 Oblique arytenoid is innervated by
the recurrent laryngeal nerve.
 Function:-
 The oblique arytenoids and
aryepiglottic muscles act as a
sphincter of the laryngeal inlet by
adducting the aryepiglottic folds and
approximating the arytenoid
cartilages to the tubercle of the
epiglottis.

42. TRANSVERSE ARYTENOIDS – UNPAIRED
 Origin:-
 Posterior surface of the muscular
process and outer edge of the
arytenoid
 Insertion:-
 Crosses over and attaches to the same
point on the other arytenoid
 Vascular supply:-
 laryngeal branches of the superior
and inferior thyroid arteries

43. TRANSVERSE ARYTENOIDS – UNPAIRED
Innervation:-
 Transverse arytenoid is
innervated by the recurrent
laryngeal nerves . It also receives
branches from the internal
laryngeal nerve.
Function :-
Adducts the vocal fold and
controls the position of the vocal
fold

44. POSTERIOR CRICOARYTENOID
 Origin:-
 Lower and medial surface of the back
of the cricoid lamina
 Insertion:-
 It fans out to be inserted into the back
of the muscular process of the
arytenoid
 Vascular supply:-
 laryngeal branches of the superior and
inferior thyroid arteries.

45. POSTERIOR CRICOARYTENOID
 Innervation :-
 recurrent laryngeal branch of the vagus
 Function:-
 Only laryngial muscle to open the glottis.
 Upper horizontal fibres rotate the arytenoids
and move the muscular processes towards
each other separating the vocal processes
and abducting the cords.
 Lateral vertical fibres draw the arytenoids
down the sloping shoulders of the cricoid
separating the arytenoids.

46. LATERAL CRICOARYTENOID
 Origin:-
 Superior border of lateral part of the
arch of the cricoid
 Insertion:-
 muscular process of the ipsilateral
arytenoid cartilage
 Vascular supply:-
 laryngeal branches of the superior and
inferior thyroid arteries

47. LATERAL CRICOARYTENOID
 Innervation :-
 1–6 branches of the anterior terminal
division of the recurrent laryngeal
nerve.
 Function:-
 Adducts and lowers the tip of the vocal
process by rotating the arytenoids
medially
 Vocal fold adducted, lowered,
elongated and thinned. The edge of
the vocal fold becomes sharp and is
passively stiffened.

48. THYROARYTENOID AND VOCALIS
 A broad sheet of muscle which lies lateral to and
above the free edge of the cricovocal ligament.
The lower part of the muscle is thicker and forms
a distinct bundle called the vocalis muscle.
 Origin:- Back of the thyroid prominence and
cricothyroid ligament.
 Insertion:- Vocal process of arytenoid and
anterolateral surface of the body of the
arytenoid.
 Vascular supply :- laryngeal branches of the
superior and inferior thyroid arteries.
 Innervation :-recurrent laryngeal nerve. It also
receives a communicating branch from the
external laryngeal nerve

49. THYROARYTENOID AND VOCALIS
 Function:-
 draw the arytenoid cartilages towards the thyroid
cartilage, thereby shortening and relaxing the vocal
ligaments.
 At the same time, they rotate the arytenoids medially
in opposition to the action of posterior
cricoarytenoid to approximate the vocal folds and so
aid closure of the rima glottidis.
 Relaxation of the posterior parts of the vocal
ligaments by the vocalis muscles, combined with
tension in the anterior parts of the ligaments, is
responsible for raising the pitch of the voice.
 Vocalis can change the timbre of the voice by
affecting the mass of the vocal cords.

50. CRICOTHYROID
 This is the only intrinsic muscle that lies
outside the cartilaginous framework of the
larynx.
 Origin:- Lateral surface of the anterior arch of
the cricoid. Fibres fan out and pass backwards
in two groups.
 Insertion:- Lower oblique fibres pass backwards
and laterally to the anterior border of the
inferior cornu of the thyroid cartilage. Anterior
straight fibres ascend to the posterior part of
the lower border of the thyroid lamina.
 Vascular supply :- Cricothyroid is supplied by
the cricothyroid artery, a branch of the
superior thyroid artery.

51. CRICOTHYROID
 Innervation:-
 external branch of the superior laryngeal nerve,
 Action:-
 Rotates the cricoid cartilage about the horizontal axis
passing through the cricothyroid joint.
 It lengthens the vocal folds by increasing the distance
between the angle of the thyroid cartilage and
arytenoids.
 On contraction, the vocal folds are brought into a line
between the anterior commissure and the posterior
cricoarytenoid ligament, the level of the vocal folds is
lowered and the entire fold elongated and thinned.
 The edge of the vocal fold becomes sharp and all the
layers are stiffened .

52. Alter the shape of laryngeal inlet
1) Aryepiglotticus :-(A continuation of the oblique arytenoid )
Origin:- Posterior aspect of the muscular process of the arytenoid
Insertion:-Fibres pass around the apex of the opposite arytenoid and insert into the aryepiglottic fold
Action:-Weak sphincter of the laryngeal inlet
2) Thyroepiglotticus:-
Origin:- Back of the thyroid prominence and cricothyroid ligament
Insertion:-Fibres pass upwards into the aryepiglottic fold
Action:- Widens the inlet of the larynx pulling the A continuation of the thyroarytenoid aryepiglottic folds slightly
apart.

53. EXTRINSIC MUSCLES OF THE LARYNX

56. ARTERIAL SUPPLY
SUPERIOR LARYNGEAL ARTERY
from superior thyroid branches of the
external carotid artery – supplies the
supraglottis
INFERIOR LARYNGEAL ARTERY
from the inferior thyroid artery off the
subclavian artery supplies the subglottis
and the undersurface of the vocal cord.

57. VENOUS DRAINAGE
SUPERIOR LARYNGEAL VEIN drains into
the superior thyroid vein, which
terminates at the internal jugular vein.
INFERIOR LARYNGEAL VEIN drains into
the thyroid venous plexus, which
usually drains into the left
brachiocephalic vein via the inferior
thyroid vein.

58. NERVE INNERVATION
larynx is innervated by the internal and
external branches of the superior
laryngeal nerve, the recurrent laryngeal
nerve and sympathetic nerves
the internal laryngeal nerve is described
as sensory, the external laryngeal nerve
as motor, and the recurrent laryngeal
nerve as mixed
All the intrinsic muscles of the larynx are
supplied by the recurrent laryngeal
nerve except for cricothyroid, which is
supplied by the external laryngeal nerve

59. NERVE INNERVATION
anastomoses between the recurrent laryngeal
nerve and the internal laryngeal branch of the
superior laryngeal nerve is called (Galen’s
anastomosis)
SUPERIOR LARYNGEAL NERVE :- The motor
(external) branch supplies the cricothyroid
sensory (internal) branch supplies the laryngeal
mucosa down to the level of the vocal folds.
RECURRENT LARYNGEAL N :- supplies motor
innervation to all other (intrinsic) larynx muscles
except cricothyroid as well as sensory innervation
to the laryngeal mucosa below the vocal folds.

60. MUCOUS MEMBRANE OF LARYNX
Most of the larynx is lined by pseudostratified ciliated columnar
‘respiratory’-type epithelium.
The upper half of the posterior surface of the epiglottis, the upper part
of the aryepiglottic fold, the posterior glottis and the vocal folds are
covered with nonkeratinizing stratified squamous epithelium
closely attached over the posterior surface of the epiglottis, the
corniculate and cuneiform cartilages and over the vocal ligament.
Elsewhere, it is loosely attached and prone to oedema.
The vocal folds do not possess any glands and the mucous membrane
is lubricated by mucus from the glands within the saccules. The
squamous epithelium of the vocal folds
is therefore prone to desiccation if these glands cease to function, for
example after radiation

61. SPACES WITHIN THE LARYNX
three main spaces are the pre-epiglottic, the
paraglottic and the subglottic spaces.
PRE-EPIGLOTTIC SPACE
lies anterior to the epiglottis, a horseshoe shaped,
primarily filled with adipose tissue and does not
appear to contain any lymph nodes.
It is bounded
anteriorly :- thyrohyoid ligament and hyoid bone

62. SPACES WITHIN THE LARYNX
Posteriorly:- epiglottis.
Superiorly :- hyoepiglottic ligament connects
the epiglottis to the hyoid bone.
Tumour may spread into this area through
small perforations in the epiglottis or directly
through the hyoepiglottic ligament.
The preepiglottic space is continuous laterally
with the paraglottic space.

63. PARAGLOTTIC SPACE
The paraglottic space is bounded
> laterally by the thyroid cartilage,
> medially by the conus elasticus
and quadrangular membrane
> posteriorly by the piriform fossa
mucosa.
It encompasses the laryngeal
ventricles and saccules

64. KEY POINTS
 Slight swelling in the subglottic larynx can cause severe airway obstruction in infants
 The preepiglottic and paraglottic spaces are connected and allow the spread of tumours within
the larynx.
 The posterior cricoarytenoid is the only abductor of the vocal cords
 All the intrisic muscles of the larynx, except the cricothyroid, are supplied by the recurrent
laryngeal nerve.
 Laryngeal carcinoma:- Squamous cell carcinoma is by far the most common laryngeal neoplasm.
 Vocal cord nodules :-Vocal fold nodules are chronic lesions of the vocal folds and develop most
commonly as the result of persistent overuse of the voice
 Reinke’s oedema:- Any tissue swelling above the vocal cord exaggerates the potential space deep
to the mucosa (Reinke’s space), causing accumulation of extracellular fluid and flabby swelling of
the vocal cords (Reinke’s oedema).