Anatomy of larynx & physiology, 29.08.16, dr.bakshi

3. [1] Organ for phonation
[2] Provides a protective sphincter at the inlet of
the air passages :
 Prevents the entry of swallowed food and
other foreign bodies
 Provides a blockade for generation of high
intrathoracic pressure for coughing and aiding
extreme muscular efforts

5.  During the 4th week of IUL, the rudiment of the
respiratory tree appears as a median
laryngotracheal groove in the ventral wall of
the pharynx.
 The groove subsequently deepens and its edges
fuse to form a septum, thus converting the
groove into a splanchnopleuric laryngotracheal
tube.
 This process of fusion commences caudally and
extends cranially but does not involve the
cranial end where the edges remain separate,
bounding a slit like aperture through which the
tube opens into the pharynx.

6.  The tube is lined with endoderm from which
the epithelial lining of the respiratory tract is
developed.
 The cranial end of the tube forms the larynx and
trachea, and the caudal end produces two lateral
outgrowths from which the bronchi and right
and left lung buds develop.

9.  Extends from root of tongue to trachea.
 Lies opposite to 3rd to 6th cervical vertebra in
men - and at a higher level in children and
women. Male Female
Length 44 mm 36 mm
Transverse diameter 43 mm 41 mm
AP diameter 36 mm 26 mm

11.  Made up of skeletal
framework of cartilages,
joints, ligaments and
membranes.
 Cavity of larynx is lined
by mucous membrane
which is continuous
above and behind with
that of the pharynx and
below with that of the
trachea.

12. 1. Size - smaller in infants.
2. Shape - funnel shaped.
3. Softness - cartilages are softer.
4. Superiorly placed in infants.
5. Straighter and less oblique in infants.
6. Sensitivity - greater in infants.
7. Subglottis - very narrow.

14. 9 cartilages :
 3 unpaired: Thyroid cartilage
Cricoid cartilage
Epiglottis
 3 paired : ArytenoidS
Corniculate (Cartilage of Santorini)
Cuneiform (Cartilage of Wrisberg)

15. THYROID CARTILAGE:
• Shield like.
• Largest of all the cartilages.
• Anteriorly 2 lamina - join together in the midline
inferiorly but anteriorly they do not meet forming
thyroid notch.
• Angle of fusion of lamina : 90 degrees in men
120 degrees in female
• Fused anterior borders form a projection called the
laryngeal prominence (Adam’s apple)
• Posteriorly the lamina diverge.
 Posterior border of each prolong to form 2 slender
processes – superior and inferior cornua

17. 1. Superior cornu : Long, narrow and curves upwards,
backwards and medially.
- Lateral thyroid ligament is attached to this cornu.
2. Inferior cornu : short,thicker,curves downwards & medially.
- Articulates with cricoid cartilage.
 Oblique line : Present on the external surface of each lamina,
it extends from the superior thyroid tubercle to the inferior
thyroid tubercle.
- Gives attachment to thyrohyoid, sternothyroid, inferior
constrictors.
 Superior border of each thyroid lamina gives attachment to
corresponding half of thyrohyoid ligament.
 Inferior border is divided to into halves on each side by
inferior tubercle.
 Cricothyroid membrane is attached to medial portion of
inferior border.

18. CRICOID CARTILAGE:
 Only complete cartilage.
 Signet -ring shaped.
 Forms most of the posterior part of larynx.
 Posteriorly - broad lamina.
 Anteriorly - narrow arch.
 Articulates with inferior cornu of thyroid cartilage,
near the junction of arch and lamina.
 Lamina has articular facets for arytenoids.
 Vertical ridge in midline of lamina gives attachment to
longitudinal muscles of oesophagus.
 Lined with mucous membrane over entire surface.

20. ARYTENOID CARTILAGE:
 2 in number
 Present on the upper and lateral borders of cricoid
cartilage.
 Irregular 3 sided pyramid.
 2 processes:
Vocal process.
Muscular process.
.
-articulates with corniculate and gives attachment to
the aryepiglottic folds.

22. .
 Posterior surface - covered by transverse arytenoid.
 Base - concave, smooth surface for articulation with
cricoid.
 Synovial joint.
 Capsular ligament is loose, allowing both rotatory and
medial and lateral gliding movements.

23. CORNICULATE CARTILAGE:
 2 small, conical nodules.
 Elastic fibrocartilage.
 Synovial joint.
 Situated in posterior part of aryepiglottic folds of
mucosa.
CUNEIFORM CARTILAGE:
 2 small, elongated flakes.
 Elastic fibrocartilage.
 Present ventral to the corniculate cartilage.

25. EPIGLOTTIS:
 Elastic fibrocartilage
 Thin, leaf like
 Projects upwards behind the tongue and body of hyoid.
 Attached to thyroid cartilage by a narrow stalk just below
the thyroid notch.
 Sides of the epiglottis are attached to arytenoid cartilages by
aryepiglottic folds.
 Posterior surface of epiglottis is concave, smooth.
 Anterior surface –free, covered with mucous membrane.
 Mucous membrane is reflected onto pharyngeal part of
tongue - median glossoepiglottic fold.
 Also to lateral wall of pharynx - 2 lateral glossoepiglottic
folds
 Depression between the two folds – Vallecula.

26.  Hyoepiglottic ligament connects epiglottis to
the hyoid bone in front.
 The epiglottis is attached to the inner surface of
the thyroid cartilage just below the thyroid
notch by the thyroepiglottic ligament.
 The space between the epiglottis and the
thyrohyoid membrane is filled with fatty tissue
and is called the pre-epiglottic space.

27. Calcification of laryngeal cartilages:
 Corniculate, cuneiform, epiglottis and apices of
arytenoids are elastic fibrocartilages - little tendency to
calcify.
 Thyroid, cricoid, greater part of arytenoids are hyaline
cartilages - begin to calcify in late teens.
 Thyroid calcification starts in inferior cornu.
 Calcification of muscular process and body of
arytenoids -4th decade.
 Calcification of posterior part of cricoid lamina and
posterior part of arytenoids – confused as foreign body
radiologically.

28. LIGAMENTS:
 Extrinsic ligaments : Thyrohyoid membrane.
Hyoepiglottic ligament.
Cricotracheal ligament.
 Intrinsic ligaments : Quadrate membrane.
Cricovocal membrane.

30. THYROHYOID MEMBRANE:
 Joins thyroid cartilage and hyoid bone (greater
cornu and upper border of posterior surface of
body of hyoid)
 Fibroelastic tissue.
 Median and lateral parts are thickened.
 Median - Median thyrohyoid ligament.
 Lateral - Lateral thyrohyoid ligament - connects
superior cornu of thyroid to posterior end of
greater cornu of hyoid.
 Cartilago triticea - a small nodule in the ligaments.
 Membrane is pierced by
Internal branches of superior laryngeal nerve
Superior laryngeal vessels.

31. CRICOTRACHEAL LIGAMENT:
 Connects lower border of cricoid with 1st tracheal ring.
HYOEPIGLOTTIC LIGAMENT:
 Connects epiglottis to body of hyoid.

32.  A fibroelastic membrane lying beneath the
mucous membrane of larynx.
 Divided into 2 parts by laryngeal ventricle.
 Upper part : Quadrilateral membrane.
 Lower part : Cricovocal ligament.

34. Quadrilateral membrane :
 Extends from arytenoid to the epiglottis.
 Upper border forms aryepiglottic fold.
 Lower free border is thickened - vestibular ligament.
Cricovocal membrane:(conus elasticus)
 Thick membrane.
 Extends upwards and medially from the arch of cricoid
cartilage.
 Stretched between the midpoint of laryngeal
prominence of thyroid cartilage anteriorly to the vocal
process of arytenoid behind.
 Free upper border - Vocal ligament.
 Anteriorly thickened - Cricothyroid ligament.

35. CAVITY OF LARYNX
 Starts at the inlet of larynx.
 Ends at the lower border of cricoid.
 Divided into 3 compartments by the ventricular and
vocal folds :
1. Superior vestibule : above vestibular folds.
2. Ventricle : between vocal and vestibular folds.
3. Subglottic space : from vocal folds to lower border of
cricoid.
 A fissure between the vestibular folds : Rima vestibuli
 A fissure between the vocal folds : Rima glottidis(glottis)

36. Laryngeal inlet:
 Superiorly : Free edge of epiglottis.
 On either side : Aryepiglottic folds.
 Posteriorly : Mucous membrane between the two
arytenoid cartilages.

39.  2 thick pink folds of mucous membrane.
 Enclose vestibular ligament.
 In front - fixed to angle of thyroid cartilage below the
attachment of epiglottic cartilage.
 Behind - to anterolateral surface of arytenoid cartilage
over vocal process.

40.  2 fold like structures.
 Extends from middle of angle of thyroid cartilage to
vocal process of arytenoids
 Made up of mucosa and muscle.
 The strict anatomical definition of the vocal cord is
that part of the free edge of the cord, covered by
squamous epithelium, which has a vertical height of
about 5mm, being bounded superiorly and inferiorly
by the superior and inferior arcuate lines.
 The free edge of the vocal cord is covered by
squamous epithelium.
 Its superior and inferior surfaces are covered by
respiratory epithelium and the junction between the
respiratory and squamous epithelium above and below
is marked by the superior and inferior arcuate lines,
respectively.

41.  Mucosa consists of : Epithelium (stratified squamous)
Lamina propria :
-superficial layer
-intermediate layer
-deep layer
 Superficial layer vibrates most significantly during
phonation.
-Consists of loose fibrous tissue.
 Intermediate layer - consists of elastic fibers.
 Deep layer - collagenous fibers rich in fibroblasts.
 Intermediate + deep layer  Vocal ligament.
 Anterior macula flava and posterior macula flava are
present along the edge of vocal fold.
-serve as a cushion and protect the ends from
mechanical damage caused by vocal fold vibrations

43.  Vocal fold is a multilayered vibrator.
 Mechanically divided into 3 layers:
1) Cover :
- Epithelium and superficial layer of lamina
propia
2) Transition :
- Intermediate and deep layers of the lamina
propia
3) Body :
- Vocalis muscle

44.  Elongated fissure between vocal folds - anteriorly
and the - vocal processes and bases of arytenoids –
posteriorly
 Limited behind by mucous membrane between
arytenoid cartilages with top portion of cricoid
cartilage as its base.
 3/5th of the length - Intermembranous part.
 Remainder lies between vocal processes-
Intercartilagenous part.
 Length of glottis : 23mm - Men.
16-17mm - Women.
The glottis is said to consist of the vocal cords, the
space which lies in a horizontal plane 1 cm inferior
to the level of the upper surface of the vocal cord,
the anterior commissure and posterior
commissure.

46. SUBGLOTTIS:
 Lower part of laryngeal cavity.
 From the level of vocal folds to the lower border of
cricoid cartilage.
 Upper part - elliptical.
 Lower part - widens and becomes circular.
 Lined with mucous membrane.

47.  The subglottis can be divided into 2 parts.
 The anterior fixed part is a triangle whose apex
lies superiorly at the anterior commissure.
 Here, the mucosa is tightly bound to the
cartilage, which has foramina through which
tumour can pass.

48.  Extrinsic : Maintain position of larynx in
neck.
 Intrinsic : Regulate mechanical properties of
vocal folds.

49. BELOW THE HYOID
BONE:
ABOVE THE HYOID
BONE:
 1) Thyrohyoid
2) Sternohyoid
3) Sternothyroid
4) Omohyoid.
 1) Mylohyoid
2) Geniohyoid
3) Stylohyoid
4) Stylopharyngeus
5) Palatopharyngeus
6) Salpingopharyngeus.

52. CRICOTHYROID:
 Origin:
- Lower border and lateral surface of cricoid cartilage.
 Insertion:
- Lower border of thyroid cartilage.
- Inferior cornu
 Actions:
- Rotates cricoid cartilage about a horizontal axis.
- Lengthens the vocal folds by increasing the distance
between the angle of thyroid cartilage and arytenoids.

53. POSTERIOR CRICOARYTENOID:
 Origin:
- Posterior surface of lamina of cricoid cartilage.
 Insertion:
- Posterior aspect of muscular process of arytenoid
cartilage.
 Actions:
- Opens the glottis.
- Abductor of vocal cord.

54. LATERAL CRICOARYTENOID:
 Origin:
- Lateral part of upper border of arch of cricoid
cartilage.
 Insertion:
- Front of muscular process of arytenoids.
 Actions:
- Adducts the vocal process.
- Vocal fold - adducted, elongated, thinned.

55. TRANSVERSE ARYTENOID:
 Origin:
- Posterior surface of muscular process of
arytenoid.
 Insertion:
- Similar place on the other arytenoid.
 Actions:
- Adductor of vocal cord.

57. OBLIQUE ARYTENOID:
 Origin:
- Posterior aspect of muscular process of one
arytenoid.
 Insertion
- Apex of other arytenoid.
- Few fibers prolong into aryepiglottic fold
 Actions:
- Adducts the vocal fold(inter cartilagenous
part)

59. THYROARYTENOID (Vocalis) :
 Origin:
-posterior aspect of angle of thyroid cartilage.
-adjacent part of cricothyroid ligament.
 Insertion:
vocal process
-anterolateral surface of cartilage.
- Fibres of the thyroarytenoid are prolonged into the
aryepiglottic fol, some continuing to the margin of the
epiglottis as the thyroepiglotticus.
 Actions:
1) Thyroepiglotticus - widens the inlet of larynx
2) Vocalis - tensor of vocal cord

62.  Muscles which abduct vocal fold:
Only posterior cricoarytenoid.
 Muscles which adduct vocal cord:
1) Lateral cricoarytenoid.
2) Interarytenoid.
3) Thyroarytenoid.
 Muscles which tense vocal cord:
- Vocalis.
 Closers of inlet of larynx:
1) Aryepiglotticus.
2) Oblique arytenoids.

63. MOVEMENTS OF VOCAL FOLDS
 Affect the shape and size of rima glottidis.
1. During quiet breathing:(rest)
- intermembranous part of cord is triangular.
- intercartilagenous part is quadrangular.
2. During phonation or speech:
- intermembranous and intercartilagenous parts are
reduced to a linear chink by adduction of vocal folds
and adduction and medial rotation of arytenoid
cartilages.

64. 3. During forced inspiration:
- vocal fords undergo extreme abduction.
- rima are triangular.
- arytenoids rotated laterally and vocal process
move widely apart.
4. During whispering:
- intermembranous part is closed.
- intercartilagenous part is opened.

65.  Mucous glands are freely distributed throughout.
 Mucous glands are numerous over the posterior
surface of epiglottis, margins of lower part of
aryepiglottic fold and saccule.
 Vocal folds are devoid of glands.
 The mucous membrane is lubricated by the glands
within the saccules.
 The squamous epithelium covering the vocal folds
is therefore susceptible to dessication.

66. 1. Laryngeal branches of superior and inferior thyroid
arteries.
2. Cricothyroid branch of superior thyroid artery.
Superior thyroid artery  arises from  ECA
Inferior thyroid artery  arises from  Thyrocervical
trunk of first part of subclavian artery.

67.  Superior vessels enter internal jugular vein by way of
superior thyroid or facial vein.
 Inferior vessels drain into brachiocephalic veins by
way of inferior thyroid vein.
 Some venous drainage from the larynx is by way of the
middle thyroid vein into the internal jugular vein.

68.  Separated by vocal folds into : (1) Upper group
(2) Lower group
 Upper group - upper deep cervical lymph nodes.
 Lower group - lower part of deep cervical chain.

69.  The supraglottic portion of the larynx is
derived from the buccopharyngeal anlage
(arches III and IV), whereas the glottic and
subglottic portions derive from pulmonary
anlage (arch VI).
 Thus, each major component has an
independent lymphatic circulation, separated
into an upper and a lower drainage system.

70.  A vocal fold contains only a few capillary
vessels.
 It is this poverty of lymph drainage which
predisposes Reinke’s space to accumulation of
oedema.

71.  From vagus by way of
(i) superior laryngeal nerve
(ii) recurrent laryngeal nerve.

72. SUPERIOR LARYNGEAL NERVE:
 Arises from inferior ganglion of vagus.
 Receives a branch from superior cervical sympathetic
ganglion.
 Descends lateral to pharynx,behind the internal carotid
artery.
 At the level of greater horn of hyoid
small external branch large internal branch.
supplies motor branch pierces thyrohyoid membrane
cricothyroid muscle sensory somatosensory

74. [3] REINKE’S SPACE
 It lies immediately beneath the laryngeal
mucosa, i.e superficial to the vocal ligament
 It is bounded superiorly and inferiorly by the
junction of the columnar and squamous
epithelium which represents the superior and
inferior arcuate lines.

75. PHYSIOLOGY OF LARYNX

76.  PROTECTION OF AIRWAY
 ROLE IN DEGLUTTION
 ROLE IN RESPIRATION
 INVOLUNTARY REFLEXES
 FIXATION OF CHEST
 PHONATION

77. LARYNX ACTS AS SPHINCTER AT
INLET OF AIRWAY
AT SAME TIME IT MAINTAINS A
PATENT AIRWAY DURING
INSPIRATION SUSTAINING A GREAT –
VE PRESSURE
SO IT IS FORMED OF A RIGID
CARTILAGENOUS FRAMEWORK WITH
MOBILE PARTS TO PROVIDE BOTH
ACTIONS

78.  RECEPTORS:THERMO & CHEMORECEPTOR
MOST DENSE IN SUPRAGLOTTIS
 AFFERENT:INTERNAL LARYNGEAL NERVE
 EFFERENT:VAGUS NERVE
 LARYNGOSPASM CAN OCCUR IN
SUSCEPTIBLE PEOPLE
 THIS REFLEX IS WEAK IN INFANTS &
STRENTH INCREASE WITH MATURATION
& MYELINATION COINCIDING WITH
INCIDENCE OF SIDS

79.  ANTERIOR AND UPWARD MOVEMENT OF
LARYNX
 DIRECTS FOOD TOWARDS HYPOPHARYNX
 RELAXES UES AT END OF PHARYNGEAL
PHASE

80.  BEST ADAPTED FOR REGULATING
AIRWAY
 WIDENING OF GLOTTIS DURING
INSPIRATION IS A PRIMARY ACTION OF
VENTILATION
 PCA THE ONLY DIALATOR, CONTRACTS
EVEN BEFORE THAT OF DIAPHRAGM
 PCA ACTIVITY VARIES WITH BREATHING

81.  LARYNX DENSELY SUPPLIED WITH
SENSORY RECEPTORS
 THERMORECEPTORS
 CHEMORECEPTORS
 PROPRIORECEPTORS
 DIRECT EFFECT ON BLOOD PRESSURE:
HYPERTENSION
 DIRECT AFFECT ON HEART:
BRADYCARDIA

82.  CONTRACTION OF EXTRINSIC
LARYNGEAL MUSCLES FIXES CHEST
DURING CLIMBING AND OTHER
STRENOUS EXERCISES.

83.  PHONATION: GLOTTIS / PRODUCTION OF
VOICE
 RESONANCE: SUPRAGLOTTIS, PHARYNX,
NOSE, CHEST / MODULATION OF VOICE
 ARTICULATION: TONGUE, PALATE, LIPS /
SHAPING INTO WORDS

84.  5 PRE-REQUISITES:
 ADEQUATE BREATH SUPPORT
 APPROXIMATION OF VOCAL FOLDS
 FAVOURABLE VIBRATORY PROPERTIES
 FAVOURABLE VOCAL FOLD SHAPE
 CONTROL OF LENGTH AND TENSION

85.  BODY-COVER CONCEPT

88. VIBRATORY CAPACITY OF VC:
 PHYSICAL PROPERTIES ARE CRUCIAL
 MUCOSA FREELY UNDULATES OVER
UNDERLYING VOCAL LIGAMENT
 MOST SUPERFICIAL LAYER OF LAMINA
PROPRIA (REINKE’S SPACE) ACTS AS
SHOCK ABSORBER

89.  HIGH SPEED PHOTOGRAPHY
 STROBOSCOPY
 ELECTROGLOTTOGRAPHY
 ECHOGLOTTOGRAPHY
 ELECTROMYOGRAPHY

95. THANK
YOU