ppt. of anatomy of larynx.

1. Anatomy of Larynx
‘the organ of voice’
Presenter : Kanato T

2. INTRODUCTION:
 The larynx is an air passage, a sphincter and
an organ of phonation.
 Generation of intrathrocic pressure for
coughing and lifting.
 Extends from the tongue to the trachea
 It is mobile on deglutition
 Understanding of basic laryngeal anatomy is
must for all ENT surgeon for Surgery & route
of cancer spread.

3. Larynx(lar´inks)- ‘the organ of voice’
 General Description
 Embryology and development
 Cartilages
 Laryngeal joints
 Ligaments & Muscles ( Extrinsic and Intrinsic)
 Mucous membrane
 Cavity of larynx
 Spaces
 Nerve supply
 Blood supply & Lymphatic drainage
 Comparative anatomy ( infant Vs adult)

4. General Description.
 Larynx extends from laryngeal inlet to the lower border of
cricoid cartilage.
 At rest, the larynx lies opposite the third to sixth cervical
vertebrae in adult males; it is somewhat higher in children
and adult females
 A-P diameter is about -36mm (M)
-26mm (F)

5. Laryngeal framework.
 Consist of :
 Hyoid bone
 Cartilages
 Ligaments & membrane
 Extrinsic & intrinsic muscles
 Lined by mucus membrane
 Adipose & loose connective tissues filling
space

6. General principles of development
 The development of the larynx can be divided into
prenatal and postnatal stages.
 At birth, the larynx is located high in the neck
between the C1 and C4 vertebrae, allowing
concurrent breathing or vocalization and deglutition.
 By age 2 years, the larynx descends inferiorly; by
age 6 years, it reaches the adult position between
C4 and C7 vertebrae. This new position provides a
greater range of phonation (because of the wider
supraglottic pharynx) at the expense of losing this
separation of function, i.e., deglutition and breathing.

7. Embryology
 The larynx develops from the endodermal lining and the
adjacent mesenchyme of the foregut between the fourth
and sixth branchial arches.
 At 20 days' gestation, the foregut is first identifiable with a
ventral laryngotracheal groove. It continues to deepen
until its lateral edges fuse.
 Trachea becomes separated from the esophagus by the
tracheoesophageal septum with a persistent slit like
opening into the pharynx
 This fusion occurs in the caudal-to-cranial direction, and
incomplete fusion results in development of persistent
communication between the larynx or trachea and the
esophagus

10. Embryological development
 Hypobranchial eminance  Epigloittis
 2nd
Arch(hyoid arch or Reichert’s cartilage)  Upper part of
body of hyoid bone, lesser cornua of hyoid bone.
 3rd
Arch  Lower part of body of hyoid bone and greater
cornua.
 4th
Arch Upper part of thyroid cartilage, cricothyroid
muscle. ( 4th
arch nerve Superior laryngeal nerve)
 6th
Arch Lower part of thyroid cartilage, cricoid cartilage,
corniculate cartilage, cuneiform cartilage and intrinsic
muscles of larynx. (6th
Arch nerve Recurrent laryngeal
nerve).

12. Sequence of events :
 Respiratory system – outgrowth of primitive pharynx
 3.5 weeks – laryngotracheal groove, ventral aspect of
foregut
 3 weeks - Hypobrancial eminence – gives rise to furcula ->
epiglottis
 5th week – Arytenoid masses
 5-7 weeks – laryngeal lumen is obliterated
 9 weeks – oval shape lumen reestablished
 8-10 weeks – Formation of true and false vocal cords
 12th week – ventricles
 Laryngeal muscles – derivatives of mesoderm of 4th and
5th arches (CN X)

13.  The main changes occurring in the larynx
postnatally are a change in the axis, luminal
shape, length, and proportional growth of the
laryngeal elements.
 The larynx grows rapidly during the first 3
years of life, while the arytenoids remain
approximately the same size.
 Beginning at age 18-24 months, the larynx
descends in the neck to achieve its final
position at vertebrae C4-C7 by age 6 years.

14.  The larynx elongates as the hyoid, thyroid,
and cricoid cartilages separate from each
other
 The cricoid cartilage continues to develop
during the first decade of life, gradually
changing from a funnel shape to a wider adult
lumen; therefore, it is no longer the narrowest
portion of the upper airway.

15. Congenital Anomalies
 Congenital malformations of the larynx are
relatively rare but may be life-threatening.
 The most common causes include
laryngomalacia, vocal cord paralysis, and
subglottic stenosis.
 Laryngomalacia  excessive flaccidity of
supraglottic larynx which is sucked in during
inspiration producing stridor and cyanosis.

16. Congenital Anomalies
 Laryngeal atresia occurs if the endolarynx fails
to recanalize. Immediate tracheotomy is
required for survival.
 Laryngeal webs occur when the epithelium
partially fails to resorb. A weblike mass may
appear at the glottic level, often with significant
subglottic extension.
 Subglottic stenosis is a deformity in the
development of the normal cricoid cartilage
(sixth branchial arch).
 Laryngotracheal cleft results from a failure to
form the tracheoesophageal septum.

17. Hyoid bone
 The hyoid bone is a U-Shaped bone,
provides attachment for extrinsic muscles of
larynx.
 It consist of a body, greater cornua and
lesser cornua.

18. Laryngeal Cartilages
 Paired
 Arytenoid cartilage
 Corniculate cartilage
 Cuneiform cartilage
 Unpaired:
 Thyroid cartilage
 Cricoid cartilage
 Epiglottis

21. Thyroid Cartilage (oblong shield)
 Shied shaped, open posteriorly, angulated
anteriorly
 Angulation more acute in males(90 d)
 females(120 d)
 Its function is to shield larynx from injury
and provide an attachment to vocal cords

22.  This cartilage has 2 alae/wing which meet
anteriorly, they form a depression called the
THYROID NOTCH before meeting at the
protruberance of the Adam’s apple or laryngeal
prominence.
 Posterior border of each lamina prolonged
above and below to formed superior & inferior
cornu
 Superior cornu-Lateral thyroid ligament attached
 Inferior cornu- Articulate with cricoid cartilage
 Ossifies at 20-30 years of age, begins in the
inferior margin and progress cranially

23. Thyroid Cartilage
 On the external surface an oblique line curve
downwards and forwards from superior
thyroid tubercle to inferior thyroid tubercle.
 This line marks the attachment of thyrohyoid,
sternothyroid and inferior constrictor musscle.

24. Inner aspect of thyroid cartilage
 Inner aspect just below thyroid notch in midline-
Attached thyroepiglottic ligament
 Below this on each side of midline-Attached
vesicular &vocal ligament , thyroarytenoid,
thyroepiglottic and vocalis muscle.

25. Cricoid Cartilage
 Signet ring shaped
 Hyaline cartilage
 Stronger than thyroid
cartilage.
 Lamina – 2 to 3 cm
from above
downwards,
considerably broader
than anterior arch.

26. 5.
Lamina – flat portion of the ring located
posteriorly and extends upward to form the
POSTERIOR border of the larynx
Level: Adult: C6-C7 Children: C3-C4
Posterolaterally, cricoid articulates w/ Inferior
cornu of the thyroid cartilage, which forms true
synovial joints (permit a ROCKING action of the
cricoid cartilage on the thyroid cartilage and a
slight anteroposterior SLIDING motion (cricoid
cart. Supports the 2 arytenoid cartilages on
posterosuperior aspect)

27.  Important from structural & functional point of
view
 Base for entire larynx
 Support to arytenoid
 Attachment to intrinsic muscles
 Only part of cartilagenous framework that
forms the complete ring.
 Once injured or strictured , difficult to resect
while preserving laryngeal function

28. Epiglottis
 Thin leaf shaped fibro-cartilage,
situated in midline
 Upper free end broad & rounded,
projects up behind base of tongue
 Narrow base called petiole
 This attachment forms lower limit of
pre-epiglottis space

29.  Attached to the INSIDE of the thyroid cartilage. anteriorly
and projects upward and backward above the laryngeal
opening.
 The epiglottis is attached to the hyoid bone by the
hyoepiglottic ligament.
 To the posterior part of the tongue by the median
glossoepiglottic fold.
 To the sides of the pharynx by the lateral glossoepiglottic
folds.
 To the thyroid cartilage by the thyroepiglottic ligament.
 The mucous membrane covering the epiglottis is
reflected to the posterior part of the tongue as one
medial and two lateral glossoepiglottic folds. Between
these folds are depressions called epiglottic valleculae.

30.  Half of epiglottis
projects above
hyoid
 This part has a
laryngeal and
lingual surfaces

31.  Infrahyoid portion has
no free anterior
surface
 Forms posterior wall
of PreEpiglottic Space
 Epiglottic cartilage
contains many pits
filled with mucous
glands
 Little barrier between
infrahyoid portion and
PES

32. Applied anatomy
 Most of mucosal surface of supraglottic
region covers epiglottis thus majority of
supraglottic tumour are epiglottic
 Epiglottic cartilage contain pits lacunae filled
with mucous gland thus providing less
cartilaginous barrier between infrahyoid
portion of epiglottis & pre-epiglottic space
(Tendency of spread more in infrahyoid
tumor)

33. Arytenoids
 Paired cartilages, pyramidal
in shape
 Base articulated with cricoid
 PCA & LCA muscles attach
on muscular process
 Anterior angle elongated into
vocal process which
receives insertion of vocal
ligament

34.  Anterior
 Vocal process - receives the attachement of the
mobile end of each VC
 Lateral
 Muscular process
 Articulation
 Cricoarytenoid joint

35. Corniculate Cartilages
 Fibroelastic
 Cartilages of Santorini
 Small cartilages above the arytenoid and in
the aryepiglottic folds

36. Cuneiform Cartilages
 Firboelastic cartilages
 Cartilages of Wrisberg
 Elongated pieces of small yellow elastic
cartilage in the aryepiglottic folds

37. Triticeous Cartilage
 Cartilago triticea
 Small elastic cartilage in the
lateral thyrohyoid ligament
 When calcified, it can be
mistaken as a foreign body
in soft tissue Xray films

38. Laryngeal Joints
 Cricothyroid Joint
 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
 Between the base of
the arytenoid cartilage
and the facet on the
upper border of the
lamina of the cricoid
cartilage
 Two movements:
 Rotation
 Gliding

39. Ligament & membrane of larynx
 Extrinsic ligaments/Membranes: Connect
laryngeal cartilages to hyoid bone above &
trachea below
 Thyrohyhoid membrane
 Cricothyroid membrane
 Cricotracheal membrane
 Hyoepigloittic ligament
 Intrinsic ligaments/Membranes: Connect
laryngeal cartilage together, Forming internal
framework of larynx
 Crico-vocal membrane (Conus elasticus)
 Quadrangular membrane

41. Extrinsic Ligaments
 Thyrohyoid membrane
 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

42. Extrinsic Ligaments
 Cricothyroid
membrane and
ligaments
 May be pierced
for emergency
tracheotomy
(cricothyrotomy)

43. Extrinsic Ligaments
 Cricotracheal Ligament
 Attaches the cricoid cartilage to the first attached
ring
 Hyoepiglottis
 It connects the epiglottic cartilage to hyoid bone.

45. Intrinsic Ligaments
 Fibroelastic membrane
 Divided into upper and lower parts by the
ventricle of the larynx
1) Upper part: Quadrangular membrane
Extends between lateral border of epiglottis &
arytenoids cartilage
 Upper margin-Forms aryepiglottic fold
 Lower margin- Vestibular ligament ( false cord)
 Forms part of wall between upper pyriform
sinus and laryngeal vestibule

46. Intrinsic Ligaments
2) Lower part(Thicker): Cricovocal membrane or
Conus elasticus
 It attached below to upper border of cricoid cartilage
 Upper border is free and stretches between midpoint
of laryngeal prominence of thyroid cartilage anteriorly
& vocal process of arytenoids behind
 Free upper border constitute vocal ligament (true cord)
 Anteriorly thickening Cricothyroid ligament- Connects
cricoid & thyroid cartilage in midline

48. Extrinsic muscle of larynx
 Infrahyoid group
o Thyrohyoid muscle
o Sternohyoid muscle
o Sternothyroid muscle
 Suprahyoid group
o Mylohyoid muscle
o Geniohyoid muscle
o Stylohoid muscle
o Digastric muscle
o Stylopharyngeus
o Palatopharyngeaus
o Salphingopharyngeus

50. Extrinsic muscle of larynx
Infra hyoid group:

51. Extrinsic muscle of larynx
suprahyoid group:

52. Extrinsic muscle of larynx contd
Suprahyoid group:

53. Intrinsic muscle of larynx
Open & close glottis
Posterior cricoarytenoid muscle
Lateral cricoarytenoid muscle
Transverse arytenoids (unpaired)
Oblique arytenoids (paired)
Control tension vocal folds
Thyroarytenoid(vocalis)
Cricothyroid
Acting on laryngeal inlet
Aryepigloticus ( cont.of oblique arytenoids)
Thyroepigloticus(Cont. of thyroarytenoid)

54. Aryepiglottics thyroepiglottics
Obiq. Ary
Tran. ary
Cricothyroid
Post.
cricoarytenoid

55. Muscle open & close glottis (Intrinsic)

56. Muscle open & close glottis

57. Muscle open & close glottis

58. Muscle control tension of vocal folds

59. Muscle control tension of vocal folds

60. Muscle of laryngeal inlet

62. Mucous membrane of larynx:
Lined by pseudo stratified ciliated columnar
Closely attached over posterior surface of
epiglottis, corniculate & cuneiform, vocal ligament,
elsewhere loosely attached (Oedema)
Mucous gland are freely distributed throughout
 Vocal folds do not poses any glands (lubricated
from saccules)
Non keratinizing stratified sqamous epithelium:
Upper half of posterior surface of epiglottis
 Upper half of eryepiglotic fold
 posterior glottis, vocal folds.

63. Cavity of the Larynx
Two pairs of folds- vestibular and vocal divide the
cavity into 3 parts:
1.Vestibule
2.Ventricle
3.Subglottic space

66. Cavity of the Larynx
 Vestibule – boundaries:
 Anterior: posterior surface of epiglottis
 Posterior: interval between arytenoid
cartilages
 Lateral: inner surface of aryepiglottic folds
and upper surfaces of the false cord

67. Cavity of the Larynx cont..
 Ventricle( sinus of Larynx)
 Deep elliptical space between vestibular and
vocal fold.
 Saccule – conical pouch at anterior part of
the ventricle, lies bet. Inner surface of
thyroid cartilage and false cord; has
numerous mucous glands open into the
surface of its lining mucosa for lubricating the
vocal cords.

68. Cavity of the Larynx cont…
 Glottis (rima glottidis) – space between free
margin of the true VC,
 opening/aperture
 Posterior glottic chink in adult: 18-19mm;
New born: 4mm;
 total glottic chink in a newborn: 14mm2

69. Cavity of the Larynx cont..
 Abduction:
Respiration, wide and
triangular
 Adduction: Phonation,
slit-like appearance

70. Cavity of the Larynx cont..
 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
False Cords (ventricular bands)
Anteriorly: angle of the thyroid cartilage
Posteriorly: bodies of the arytenoid
cartilage

71. Supraglottis
 Consists of ventricles,
false cords, laryngeal
surface of epiglottis,
aryepiglottic folds and the
mucosal expanse.
 Posterior tapering shape
reduces area of mucosa in
posterior region
 So majority of SG tumors
are epiglottic

72. Applied anatomy
 Inferior limit of supraglottis is
 Clinically- imaginary horizontal plane passing
through the apex of Laryngeal ventricle.
 Anatomically - superior arcuate line where the
squamous epithelium and respiratory epithelium
meet.
 The Marginal Zone comprises of Suprahyoid
epiglottis and Aryepiglottic fold(There is lack of
embryologic separation from adjacent hypopharynx
 Early lympathic spreads because of rich
vascularity and lymphatics.

73. Glottis
 Consists of true cords,
anterior commissure and
posterior commissure
 Narrow triangular space
between the true cords is
called rima glottis
 Anterior 2/3 is membranous
 Posterior third consists of
vocal processes of
arytenoids
 Posterior 1/3 of cords and
covering mucosa are called
posterior commissure

74. Applied Anatomy
 Anterior commissure is directly attached to
the thyroid cartilage by Broyle’s ligament
without intervening inner perichondrium.
 Lesion at the anterior commissure can invade
the thyroid cartilage early because of
absence of inner perichondrium.
 Since Broyle's ligament contains blood
vessels and lymphatics, it represents a
potential route for the escape of malignant
tumours from the larynx.

75. Sub-glottis
 Area at which larynx merges
with trachea
 It extend from Inferior border
of vocal fold to inferior margin
of cricoid.
 Cricoid cartilage is involve
early because of the absence
of an intervening muscle layer
in ca. subglottic.

76. Pre-Epiglottic Space
 Bound sup by hyo-epiglottic
ligament, ant by thyrohyoid
memb. & thyroid cartilage
and posteriorly by epiglottis
 Filled with fat and areolar
tissue
 Continuous with para-glottic
space
 Cx of laryngeal surface of
epiglottis readily spread to
PreEpiSpace

77. Paraglottic space:
 Bounded:
 Laterally: Thyroid cartilage
 Medially :Conus elasticus,quadriangular
membrane
 Posteriorly:Pyriform fossa mucosa
 It encompasses laryngeal ventricles & saccules
 Growths which invade this space can present in
the neck through cricothyroid space

79. Reinke’s Space
 Mucosa over the vocal
ligament loosely attached
to ligaments
 Thus there is a
submucosal space along
most of the length of truer
Vocal cord.
 Superficial layer of lamina
propria is referred to as the
REINKE’S SPACE,

80. Histology of vocal cord
Rinkes space
Vocal Ligament
(conus
elasticus)
Vocalis
Muscle
Lamina
propria

81. Applied anatomy
 Blood vessels and lymphatics are almost
absent in Reinke’s space preventing early
spread of cancer.
 It is this layer that vibrates the most during
phonation.
 Accumulation of fluid under epithelium of true
vocal cord(Reinke’s space) is called Reinke’s
oedema.

83. Nerve supply contd..
 Sup. Laryngeal N-
 Inf ganglion vagus & superior cervical sympathetic. Descend behind ICA
 At greater horn- Divide small external & larger internal branch
 External branch –
 Motor to Cricothyroid
 Internal branch-
 Pierce thyrohyoid membrane.
 Divide-Two sensory & secretomotor
 Upper- pharynx,epiglottis,valeculla,vestibule
 Lower- Aryepiglottic fold, mucous membrane up to vocal cords
 Internal branch- caries Afferent fibers from neuromuscular & stretch
receptor
 Sup. Laryngeal nerve end by anastomoses with RLN (Galens
anastomoses)

84. Nerve Supply
Superior laryngeal nerve
Internal branch
External branch
Cricothyroid
muscle
Thyrohyoid
membrane

85. Internal branch
Internal branch of superior
laryngeal nerve
Sensory
branches
Recurrent laryngeal
nerve

86. RECURRENT LARYNGEAL NERVE
 Rt RLN leaves vagus
loops Rt Subclavian A
 Ascends in tracheo-
eosophageal groove to
reached larynx.
 Lt RNL-Passes under
aortic arch and
Ligamentum arteriosum to
reach tracheoesophageal
groove.

88. Recurrent laryngeal nerve in neck
 Pass upwards with Laryngeal branch of
Inferior Thyroid Artery.
 Deep to lower border of inferior constrictor
muscle
 Enters larynx behind Cricothyroid joint
 Divide: Motor & sensory
 Motor- All intrinsic muscle except
Cricothyroid ( Ext branch SLN)
 Sensory-Laryngeal mucosa below vocal
folds

89. Laryngeal innervations -Applied anatomy
Internal laryngeal nerve:
Lies in medial wall of pyriform sinus mucosa
 Tropical anesthesia and Pain in ca pyriform
sinus
Damage to the internal laryngeal nerve produce
anesthesia in supraglottic part of larynx so that FB
can readily enter it (Breaking the reflex arc)
Damage to external laryngeal nerve cause some
weakness of phonation due to loss of tightening
effect of the cricothyroid on the vocal cord.

90. Laryngeal innervations -Applied anatomy
 Recurrent laryngeal nerve:
 Left RLN- More liable to injury (extensive
course)
 Variable relation between RLN & ITA-
 RLN may cross in front/behind/between
artery
 Right RLN more variable location whereas
Left RLN more likely posterior to artery.

91.  Semon’s law- In gradual progressive lesions
affecting the recurrent laryngeal nerve
resulting in palsy, abductors are affected first
then the adductors.
 On the other hand, in functional paralysis of
larynx, the adductors are the first to be
paralysed.

92. RLN-VARIATIONS
 Non-Recurrent
laryngeal nerve (Rt-
0.6%,Lt-0.04%)
 Proximity to gland
 Variable relation to
ITA
 Deformity from large
thyroid nodule

93. Blood Supply
 Upper Larynx
 External carotid artery
 Superior thyroid artery
 Superior laryngeal artery
 Cricothyroid artery
 Lower Larynx
 Subclavian artery
 Thyrocervical artery
 Inferior thyroid artery
 Inferior laryngeal artery

94. Venouos Drainage
 Upper Larynx
 Superior laryngeal
vein
 Superior thyroid vein
 Internal jugular vein
 Lower Larynx
 Inferior laryngeal vein
 Inferior thyroid vein
 Midddle thyroid vein
 Brachiocephalic

95. Lymphatic Drainage
 Upper & lower group by vocal folds
 Above vocal folds-
 Vessels that accompanying superior laryngeal
vein pierce
 thyrohyoid membrane to drain into Upper deep
cervical node
 Below vocal folds-
 Lower deep cervical chain through
 Pre-laryngeal(Delphian) & pre-tracheal nodes
 No lymphatic in vocal folds

96. Infant Larynx
 Positioned high in the neck- this allows the
epiglottis to meet soft palate and makes
nasopharyngeal channel for nasal breathing
during sucking.
 Laryngeal cartilage are softer ,easily
displaced, easily irritable
 Epoigloittis- longer, narrower, tubular; hence
mentioned as omega shaped.
 Thyroid cartilage is flat, cricoid cartilage is
smaller then size of glottis making subglottis
the narrowest part.

97.  Aryoepiglottic folds are disproportionately
large.
 Arytenoids are more prominent
 Mucous membrane and connective tissue are
loosely attached and easily undergo
oedematous changes.

98. Differences between Pediatric and
Adult Airway