anatomy of larynx

1. Anatomy of Larynx

2. major laryngeal functions:
 respiration, deglutition, and phonation.
 cough, clearing the airway passage
 allowing increased abdominal pressure necessary for the
Toynbee/ Valsalva maneuver.
 In deglutition and phonation, the sphincteric closure
function of the larynx is a prerequisite.
 in respiration a wide lumen with abducted vocal folds is
required

3. Embryology of larynx

4.  rudiment respiratory system arises in the fourth week as an outgrowth of the digestive tract, the so-
called laryngotracheal groove.
 The larynx itself develops from two parts: the supraglottis from the buccopharyngeal bud (fourth arch
of the branchial system) and the glottis and subglottis from the tracheobronchial bud (fifth and sixth
arch); as a consequence, also the lymphatic drainage occurs on two different ways (superior and
inferior), which has a major impact on oncologic treatment.
 An exception is the epiglottis, which appears to be a unique mammalian addition unrelated to the
ancestral branchial arches.
 The intrinsic musculature of the larynx is derived from the branchial arch mesenchyme of the fourth
through sixth arches.
 Congenital anomalies (e.g. webs, atresia, laryngeal clefts, or stenosis) can be the result of
irregularities in this early phase of embryonic development (0–8 weeks)

5.  The positional relationships of the larynx to contiguous structures undergo dramatic changes during
development. The descensus from the skull base to its position at birth happens slightly; especially,
weeks 23 to 25 seem to be a critical period of development, as portions of the cranial base are
intimately related to the larynx and its contiguous .
 the topographic position of the infant larynx lies much more cranial than in adults and causes an
overlap of the uvula and the epiglottis.
 the cricoid of a fetus or newborn projects lies anterior to the third to fourth cervical vertebral body,
whereas the adult larynx descends over the years to the sixth cervical vertebra, and in senility it
projects down to the seventh vertebral body of the neck.
 A normal finding in the infant larynx is an overlap of the hyoid bone and the thyroid cartilage. This
situation can persist as an atavistic residuum in adults and predisposes to laryngeal dysfunction

6.  CT scan of the patient demonstrating the underlying cause is the thyroid plate asymmetry
(arrows pointing at the inward buckled left thyroid plate). Additionally, this patient exhibits an
overlapping of the hyoid bone and the thyroid cartilage as an atavistic residuum (arrow).

7.  The thyroid cartilage, which is prominent in adolescents and adults, is much more difficult
to palpate in the infant neck.
 the hyoid bone itself can be located externally by palpation almost in the submental region.
 In infants, the prominent midline ridge of the thyroid cartilage, which begins at the thyroid
notch, is not present. Instead, the anterior surface is rather flat and slightly rounded.
 Following further inferiorly the cricothyroid space with its membrane is rather palpable as a
small slit, not a depression as in older humans. This fact has to be considered when
performing a cricothyroid puncture or related surgical procedures in a pediatric larynx.
 With the descensus of the larynx and its enlargement also the major externally palpable
structures of the laryngeal framework (hyoid bone, thyroid and cricoid cartilage) separate
and distance themselves, hereby forming the preliminarily described thyrohyoid and
cricothyroid membranes.

8.  Consecutively, with this laryngeal descensus also the oropharynx develops and widens up.
Endolaryngeally the elevated tip and curvature of the epiglottis is striking. This curved form increases
from birth until the age of 3 years and slabs constantly over the years to its typical paddlelike
configuration in the adult.
 The arytenoid humps are disproportionally prominent and obscure a portion of the vocal folds. At
birth, the arytenoids are very large in comparison to the dimensions of the other laryngeal structures
and the length of the cartilaginous glottis accounts for about twothird of the whole glottis length .
 about an age of 2.5 years the length between the cartilaginous and membranous glottis equalizes to
result in an inverse relationship of roughly twothird membranous and onethird cartilaginous after the
end of the growth period.
 laryngeal aditus becomes more triangular in adolescents and adults as a consequence of the
proportional diminution of the arytenoids and the lengthening of the vocal folds.
 The subglottis is a nearly rounded airspace that rapidly increases in size during the first 2 years of life
(from 13 to 28 mm2 in the means)

9.  The most caudal part of the upper pediatric airway, the trachea, measures approximately 0.5 cm in
diameter in fullterm newborns. Maximal internal diameter of the trachea in children aged less than 1
year ranges from 0.6 to 0.9 cm.
 The subglottis bounded completely by the cricoid ring is the narrowest part of the infant larynx,
especially because of its relatively thick mucosa

10. Gender-Related Differences
 Up to puberty the female and male larynges vary marginally in shape and size.
 Thereafter, while the female larynx grows slightly, the male larynx enlarges under the influence of
testosterone and growth hormone in all dimensions with the consequence of deepening the male
voice around one octave.
 Essential genderrelated differences are particularly pronounced in the thyroid cartilage
(especially in the sagittal diameters) and in the thyroid angle, forming a prominence at its upper
end, the socalled Adam´s apple .
 The rapid and strong growth especially of the thyroid cartilage during maturation can lead to
asymmetric
developments that consequently are more frequent in men.

11.  A different development of the thyroid lamina leads to an asymmetric and tilted configuration of the
endolaryngeal structures. A typical configuration can be observed: the aryepiglottic fold is situated
more posteriorly on the side of the longer thyroid plate giving the clinical impression of a socalled
arytenoid crossing or adduction asymmetry; the laryngeal prominence is shifted extramedian to the
side of the shorter plate accordingly the interarytenoid region is tilted toward the longer side both
resulting in an oblique course of the glottis.
 A strong growth of one thyroid plate very often leads to an inward buckling of the lamina in the
anterior part moving the ventricular fold medially, mimicking a ventricular fold hyperplasia.

12. Typical configuration of an asymmetrically developed thyroid plate comprising a more posteriorly situated aryepiglottic fold on the side
of the longer thyroid plate, shifting of the laryngeal prominence to the side of the shorter plate, tilting of the interarytenoid region
toward the longer side resulting in oblique course of the glottis, and inward buckling of the lamina of the anterior part of the thyroid
plate shifting the ventricular fold medially

13. Arrow
points at the extra median position of the pomum adami.

14. Laryngoscopic view presenting the features described

15.  underdevelopment of the laryngeal dimensions is not uncommon. It could be demonstrated that in
clinically diagnosed functional mutational voice disorders presenting with an abnormal high pitched
phonation, a larynx hypoplasia was the underlying cause.
 In general the female and male larynges differ significantly not only in nearly in all dimensions but
also in several biomechanically properties, so they almost can be considered as two different organs.
 Physiologic ossification of the laryngeal cartilages in females starts at the age of 50.
 In males this process begins much earlier between the ages of 18 and 20, although individual
differences are evident.
 The thyroid´s ossification is much more distinctive in men, but a fully ossified thyroid is rare before
the age of 50, in females even before the age of 75; there is no relation between the age and the
degree of ossification.
 The cricoid cartilages ossification starts in accordance with the thyroid, but it does not occur
completely.
 The arytenoids follow a few years after the other laryngeal cartilages, but they ossify completely in
senility except the vocal processes, which stay cartilaginous throughout life.

16. The framework of the larynx
 A series of cartilages connected by fibrous membranes and ligamental structures form the laryngeal
framework. Although the thyroid cartilage, the cricoid cartilage and the epiglottis are single cartilages,
the arytenoid cartilages are paired. Additionally, three paired small cartilages (corniculate or
Santorini´s cartilage on the apex of each arytenoid; cuneiform or Wrisberg´s cartilage within the fre
margin of the aryepiglottic fold; triticeal cartilage within the thyrohyoid ligament.t) can be variably
found.
 The thyroid, the cricoid, and the major portion of the arytenoid cartilages are composed of hyaline
cartilage, whereas the vocal processes of the arytenoids, the epiglottis and the small variable
cartilages (cuneiform, corniculate, triticeal) are composed of elastic fibrocartilage.
 From approximately the age of 25 the thyroid cartilage undergoes advanced calcification, but cases
of congenital premature calcifications have been also described. Hematopoietic marrow can be
present in senility.
 The hyoid bone is the only bone of the human body that is not connected to other bones by articular
joints; it is a Ushaped, backwards open bone that consists of a body (corpus) and two horns (major
and minor) on each side

17.  Attachment to the styloid process is given by the stylohyoid ligament (which can ossify over the
years) and muscle; further conjunction to the mandible, the temporal bone, and the tongue is
performed by the suprahyoid muscles, namely the hyoglossus, geniohyoid, mylohyoid and digastric
muscles, and to the pharynx by the middle con stric tor.
 The larynx itself is suspended to the hyoid by the thyrohyoid membrane and ligaments and the
thyrohyoid muscles .

18. Thyroid cartilage:
 Shield like.
 Largest of the laryngeal cartilages.
 Has two laminae meet in the midline inferiorly.
 The angle of fusion between the laminae is about 90 degree in men and 120 degrees in women.
 The fused anterior borders in men form a projection, which can be easily palpated known as Adams
apple.
 The laminae diverge posteriorly.
 The posterior border of the two laminae are prolonged as two slender processes known as the
superior and inferior cornua.
The thyroid cartilage is significantly thicker
in men than in women and in general its thickness inc reases from anterior to posterior

20. the cricoid cartilage :
 The only complete cartilage ring in the whole of the respiratory pathway.
 Shaped like a signet ring.
 Composed of of a deep broad quadrilateral lamina posteriorly and a narrow arch anteriorly.
 In adults, the mean sagittal diameter of the cricoids arch is roughly about 16 mm in both sexes,
whereas the transversal diameter is about 22 mm in men and 16 mm in women.

21. arytenoid cartilage:
 Small paired cartilages placed close together on the upper and lateral borders of the cricoid lamina.
 Pyramidal shaped.
 Has two projections, forward and lateral projections.
 The forward projection is also known as vocal process. The vocal folds are attached to the vocal
process.
 The lateral processes are also known as muscular process

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

23.  CORNICULATE AND CUNEIFORM CARTILAGES
 The corniculate cartilages are two small conical nodules of elastic
fibrocartilage which articulate through a synovial joint with the apices of
the arytenoid cartilages. They are situated in the posterior part of the
aryepiglottic fold.
 The cuneiform cartilages are two small elongated flakes of fibroelastic
cartilage, one in each margin of the aryepiglottic fold.

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

28. 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

29. 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

30. Sub-glottis
 Begins about 5mm below free
margins of VC
 Consists of a mobile upper
and fixed lower part

31. Anatomy of Larynx - Muscles
31
 Posterior cricoarytenoid
 Only abductor
 Origin lamina of cricoid
 To vocal process
 Lateral cricoarytenoid:
 Adductor
 Lateral surface of
cricoid
 To vocal process

32. Anatomy of Larynx - Muscles
32
 Thyro-artenoid
 Adductor
 Tensor
 Vocalis : most medial
part
 Interartenoid
 Adductor
 Cricothyroid
 On external surface
 Tensor

33. Anatomy of the Larynx – muscle action
33

34. Membranes of larynx
 Crico-thryoid membrane
 Thyro-hyoid membrane
 Quadrilateral membrane
 Conus elasticus
 Spaces:
 Pre-epiglottic space
 Para-glottic space

35. Ligaments attached to the thyroid cartilage:
 Thyroepiglottic ligament: elastic ligament connecting the
epiglottis to the angle of the thyroid cartilage.
 Vestibular ligament: Also known as the false vocal cord.
 Vocal ligament: Also known as the true vocal cord is
responsible for the generation of voice.

36. Laryngeal joints
 Crico-thyroid joint : between thyroid and cricoid cartilages. It’s a
synovial joint.
Tow movements occur :
 Rotation through a transverse axis .
 Gliding , slightly .

37.  Crico- arytenoid joint :
 Between arytenoid and the cricoid cartilage . It’s a synovial joint.
Tow movements occur :
 Rotation .of the arytenoid , on vertical axis . The vocal process moves medially or
laterally .
 Gliding . the arytenoid moves toward or away from each other .

38.  Ligaments and membranes of the larynx
Extrinsic and Intrinsic ligaments .
Extrinsic ligaments: connect the laryngeal cartilages to the hyoid bone above
and trachea below.
 Thyro-hyoid membrane: between the upper border of the thyroid and the
the body and greater cornua of the hyoid bone.

39.  Crico-tracheal ligament: Unites the lower border of the cricoid
cartilage with the first tracheal ring .
 Hyo-epiglottic ligament: connects the epiglottis to the back of the
body of the hyoid bone.

40. Intrinsic ligaments:
 ligaments that connect the laryngeal cartilages.
 Strengthen the capsule of intercartilagenous joints.
 Form a broad sheet of fibroelastic tissue which lie beneath the mucous
membrane of the larynx creating an internal framework .

41.  The fibroelastic membrane:
Divided into :
upper and lower part by the presence of laryngeal ventricle.
 The upper membrane is the quadrilateral membrane.
 It extends between epiglottis and the arytenoid cartilage.
 Its upper margin forms a framework for the aryepiglottic fold.
 Its lower margin is thickened to form the vestibular ligament, which underlies the
vestibular fold or false vocal cord.

42. The lower part is a thicker membrane, containing many elastic
fibers. It is also known as cricovocal ligament or cricothryoid
ligament or conus elasticus.
 Below it is attached to the upper border of the cricoid cartilage.
 Above it is stretched between the midpoint of thyroid cartilage
anteriorly and the vocal process of the arytenoid behind.
 The free upper border of this membrane forms the vocal cord.

43. Muscles of the larynx
 The extrinsic muscles .
 intrinsic muscles .

44. extrinsic muscles of the larynx
 connect the laryngeal cartilages to
Hyoid bone above and trachea below .
and maintain the position of the
larynx in the neck .
Divided Into :
 Infra hyoid group ( strap muscles )
( Thyrohyoid , Sternothyroid ,
Sternohyoid , omohyoid ) .
 Supra hyoid group
( Mylohyoid , Geniohyoid, Stylohyoid ,
Digastric , Stylopharyngeus ,
Palatopharyngeus , Salpingopharyngeus(

45. Fig. show strap muscles of the neck

46. All of the infrahyoid muscles are innervated by the ansa cervicalis from the cervical
plexus (c1-c3 ) except the thyrohyoid muscle, which is innervated by fibres only
from the 1st cervical signal nerve travelling with the hypoglosal nerve .
Action
Insertion
origin
muscle
draws the larynx
downwards .
lower edge of the
body of the hyoid
posterir surface of the
manubrium sterni and
the 1st costal cartilage
Sterno hyoid
rises the larynx if the
hyoid is fixed .
Depress the hyoid if
the larynx is fixed .
lower border of the
greater horn of the
hyoid bone
oblique line on the
thyroid ala
Thyrohyoid
Depresses the larynx
oblique line on the
thyroid lamina .
posterir surface of the
manubrium and the
1st costal cartilage
Sternothyroid
Depresses the larynx
intermediate tendon
superior border of
scapula
omohyoid
(inferior belly )
Depresses the larynx
Lateral surface of
hyoid bone
intermediate tendon
omohyoid
(superior belly )

47.  Suprahyoid group
inervation
Action
Insertion
origin
muscle
Nerve to mylohyoid
(inferior alveolar
branch of v3 )
Raises and pulls
the hyoid .
Midline raphe and
body of hyoid .
Mylohyoid line on
the inner aspect of
Mndible .
Mylohyoid
Hypoglossal (C1
root)
Raises and pulls
the hyoid forward .
Upper border of the
body of hyoid .
Genial tubercle on
Mndible .
Geniohyoid
Facial nerve .
Retractor and
elevator of hyoid for
swallowing .
Base of greater
cornu of thyroid .
Back of the styloid
(split around
digastric process )
Stylohyoid
Posterior belly – facial
nerve .
Anterior belly - nerve to
mylohyoid .
Anterior belly pulls the
Hyoid anterior and up .
posterior belly pulls
Hyoid post. and up.
Lower border of the
Mandible .fibrous sling
holds the tendon to
lesser cornu of hyoid .
Digastric notch on
the medial surface
Mastoid process .
Digastric
Glossopharyngeal
nerve
Elevates the larynx
post. Border of lamina
of th. Cart.( side wall
Of pharynx )
Medial aspect of
the styloid process .
Stylopharyng
eous
Accessory nerve
pharyngeal plexus)
)
Helps tilts the
larynx forward .
post . Border of thyroid
alar and cornu.
Palatine aponeurosis
And post. Margin of
palat .
Palatopharyn
geus
Pharyngeal plexus
Elevates the larynx
post . Border of thyroid
cart. .( side wall of
pharynx )
Eustachian tube
Salpingophar
yngeus

48. Intrinsic muscles of larynx
 The intrinsic muscles are all paired and move the cartilages in
the larynx and regulate the mechanical properties of the
larynx. They control the position and shape of the vocal
folds and control the elasticity and viscosity of each layer .

49. Divided into :
 Open and close the glottis:(lateral and posterior cricoarytenoid muscles, transverse
and oblique arytenoids).
 Control the tension of vocal ligaments :(thyroarytenoids, vocalis and cricothyroids).
 Alter the shape of the inlet of the larynx :(aryepiglotticus and the thyroepiglotticus).
Except transverse arytenoid, all these muscles are paired.
 Abductor of vocal cords : there is only one each side .
 Posterior cricoarytenoid muscle : is the only muscle that opens the glottis,
separating the vocal processes and thus abducts the vocal cords.

52.  Adductors of vocal cords : three on
each side .
 Lateral cricoarytenoid muscle:
Adducts the vocal ligaments by rotating the arytenoids medially.

53.  Transvers portion of inter arytenoid muscle :
 A single muscle.
 Adduct the vocal cord .

54.  External portion of thyroarytenoid muscle :
 A thin sheet which lies out side the vocal cord , venticle and saccule of the larynx .
 It closes the rima glottis by medial rotation of Arytenoid cartilage around
longitudinal axis .

55.  Tensors of the vocal cords : 2 on each side .
 cricothyroid muscle :
 The only intrinsic muscle that lie outside the cartilaginuos framework of the larynx .
 It is known as the External tensor .

56.  Internal portion of thyro- arytenoid ( vocalis ) m. :
 A specialized portion of the lower and deeper fibers of the thyro-
arytenoid muscle .
 It forms a triangular bundle.
 Some of its fibers gain its attachment to the vocal ligament.
 It is known as the internal tensor .

57.  Opener of laryngeal inlet :
 Fibers of thyro-epiglottic muscle is apart of the thyro-arytenoid muscle widens the
inlet of the larynx by pulling the ary-epiglottic folds slightly apart .

58.  Closers of the laryngeal inlet :
 Oblique portion of inter-arytenoid muscle is superficial to the transvers portion .
The two bundle of fibers cross each other ; closes the rima glttis .
 Ary-epiglotic muscle is prolongation of the oblique fibers of inter- arytenoid muscle
in to the ary- epiglotic fold .
All intrinsic muscles of the larynx are supplied by recurren laryngeal nerve except
Crico-thyroid m. which is supplied by external laryngeal nerve ..

59.  Interior of larynx :
The laryngeal cavity extends from the level of 3rd cervical vertebra to the lower
border of the cricoid cartilage (c6) level. At the level of cricoid cartilage it
becomes continuous with that of the trachea.

60.  False vocal cord ( the ventricular bands): which are formed by the
mucous membrane covering the ventricular ligament and the upper part
of the external portion of the thyroarytenoid muscle.
 True vocal cords : Project further into than the false cords, and
lie at a lower level. The covering epithelium is closely bound down to the
underlying vocal ligament. The blood supply is poor, hence the pearly
white appearance of the vocal cords.

61.  Vestibule :Lies between the laryngeal inlet and the edges of
the false cords.
 Bounderies:
 Posterior surface of epiglottis in front.
 Interval between the arytenoid cartilages behind.
 Inner surface of the aryepiglottic folds and upper surfaces of the
false cords on each side.

62.  Laryngeal inlet: is bounded
 superiorly by the free edge of epiglottis
 and on each side by the aryepiglottic folds.
 Posteriorly by the mucous membrane between the arytenoid cartilages.

63.  Mucous membranes of the larynx :
 Most of the larynx is lined by pseudo stratified 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.
 Mucous glands are freely distributed throughout the mucous membranes and are
particularly numerous on the posterior surface of the epiglottis and in the
margins of the lower part of the aryepiglottic folds and in the saccules.
 The vocal folds do not possess any glands and the mucous membrane is lubricated
by mucus from the glands within the saccules.
 The squamous epethelium of the vocal folds is therefor Pron to desiccation if these
glands cease to function, for example after radiation .

64.  Ventricle of larynx:
 between the vestibular and vocal folds, overlie the ligaments of the same name.
 On each side the laryngeal ventricle opens into an elongated recess known as the laryngeal
sinus.
 From the anterior part of the ventricle, a pouch called the saccule of the larynx ascends
between the vestibular folds and the inner surface of the thyroid cartilage.
 The mucous membrane of saccule contains numerous mucous secreting glands. These
secretions lubricates the vocal cord.

65.  Rima glottis: is an elongated fissure present between the two vocal folds.
 Rima vestibuli :The rima vestibuli is the triangular-shaped opening between the 2
adjacent vestibular folds.

66.  Pyriform recesses :
The pyriform recesses (pyriform sinuses) are present on either side of
the anterolateral wall of the laryngopharynx. They are bounded medially
by the aryepiglottic folds and laterally by the thyroid cartilage and
thyrohyoid membrane. They are a common place for food to become
trapped.

67.  Spaces within the larynx :
 Preepiglottic space: Is a wedge shaped space lying in front of the epiglottis. It is
bounded anteriorly by the thyrohyoid ligament and the hyoid bone. This space is
continuous laterally with that of paraglottic space. Tumour may spread into this area through
small perforations in the epiglottis or directly through, the hyoepiglottic ligament.

68.  Paraglottic space: is a potential space present on either side of glottis. It is bounded by
the mucosa covering the lamina of thyroid cartilage laterally, the conus elasticus and
quadrangular membranes medially and the anterior reflection of the pyriform fossa mucosa
posteriorly .

69. Blood supply of the larynx : Is derived from the
 laryngeal branches of the superior thyroid arteriy . .
 laryngeal branches of the inferior thyroid arteriy .
 the cricothryoid branch of the superior thyroid artery.
The superior thyroid artery arises from the external carotid artery, and the inferior thyroid artery arises from
the thyrocervical trunk.
The veins leaving the larynx accompany the arteries;
 The superior vessels drain to the internal jugular vein by
way of the superior thyroid or facial veins ,
 The inferior vessels drain by way of inferior thyroid vein
into the brachiocephalic veins.
 Some venous drainage also occur
through the middle thyroid vein into the internal jugular vein.

70.  Lymphatic drainage:
Separated by the vocal folds into an upper and lower group:
 The part of the larynx above the vocal folds is drained by vessels accompanying
the superior laryngeal vein,
 The zone below the vocal folds drains together with the inferior vein, into the
lower part of the deep cervical chain often through the prelaryngeal and
pretracheal nodes.
 The vocal folds are devoid of lymphatics, and it infact clearly forms the watershed
zone between the upper and the lower group of lymphatics.

71.  Nerve supply of the larynx :
The larynx is supplied by branches of vagus nerve .
 Superior laryngeal nerve has two laryngeal branches :
Internal branch . Entirly sensory . It pierces the thyrohyoid membrane with the
superior laryngeal artery and vien . It supplies the cavity of the larynx as far down
the level of the vocal cords .
External branch . Travels down on the inferior constrictor muscle of the pharynx .
It supplies the cricothyroid muscle and part of the ant. Subglottis .

72.  Recurrent laryngeal branch of the vagus nerve (CN X) :
It has much longer course on the left side than on the right side .
On the lt. side it Turns round the arch of aorta .
On the rt. Side it Turns round the subclavian artery.
In the neck it lies between the trachea and oesophagus as it approach the larynx .
Its terminal part pass upwards , under cover of ala of the thyroid cartilage , immidiately behind the
cricothyroid joint .
Devided In to :
 An antero lateral ( motor branch ) : which supply all the intrinsic ms. Of the larynx except
the cricothyroid m.
 Posteromedial ( sensory branch) : which supplies the cavity of the larynx below the
level of vocal cords .

73. Intrinsic muscles

74. Cricothyroid Muscle

75. Adductors of the Vocal Folds

76. Abductor of Larynx

77. Nerve Supply: Derived from the Vagus
 Superior Laryngeal Nerve -It
leaves the vagus nerve high in
the neck
 Internal -It provides sensation of
the glottis and supraglottis,
which includes the pharynx,
underside of the epiglottis and
the larynx above the cords.
Remember: SIS-superior
internal sensory.
 External -It supplies motor
function to the cricothyroid
muscle which tenses the vocal
cords and could cause
laryngopasm.

78.  Recurrent Laryngeal Nerve -It
provides sensation to the
subglottic area which includes
the larynx below the vocal cords
and upper esophagus. It
provides motor function to the
intrinsic muscles of the larynx.
 It branches from the vagus in
the mediastinum and turns back
up into the neck. On the right, it
travels inferior to the subclavian
and loops up, and on the left it
travel inferior to the aorta and
loops up.

79. ARTERIAL SUPPLY
 Sup. Laryngeal A. from
Sup. Thyroid artery
 Inf. Laryngeal A. from
Inf. Thyroid artery