1. ANATOMY OF LARYNX
AND ITS ANAESTHETIC
IMPORTANCE
Presented by
Dr Sindhu Sapru
Moderator
Dr. S.P Meena

2. Larynx
 An air passage, a sphincter and an organ
of phonation.
 Upto puberty – Male and female larynx similar in
 Extends from root of tongue to trachea
size after that male larynx enlarges considerably
 At Rest
and continue until 40 years of age.
– Lies opposite 3rd-6th cervical vertebra in adult
male
– Some what higher in children( 2nd and 3rd
cervical vertebrae) and females

3. Difference between male and
female larynx
Male Female
Length 44 mm 36 mm
Transverse diameter 43 mm 41 mm
Sagittal diameter 36 mm 26 mm

4. Embryology
 Internal lining of larynx
Endoderm
 Cartilage and muscle
Mesenchyme of 4th and 6th Pharyngeal arches
 Rapid proliferation of mesenchyme
Change in laryngeal orifice from sagittal slit to T-shaped opening
Transforms into thyroid, cricoid and arytenoid cartilages
 Rapid proliferation of epithelium
Temporary occlusion of lumen
Vacuolization and recanalization
Formation of laryngeal ventricles
False and true vocal cords.

5.  All laryngeal muscles innervated by
10 th cranial nerve
 Superior laryngeal N. innervate
derivatives of 4 th pharyngeal arch
 Recurrent laryngeal N. innervate
derivatives of 6 th pharyngeal arch

6. Skeleton of Larynx
 Series of cartilages interconnected by
 Corniculate, and fibrous membrane and moved by
ligaments cuneiform, tritate, epiglottis and apices of
arytenoid of muscles. of elastic fibrocartilage with little
number are composed
Laryngeal Cartilages
tendancy to calcify.
 Thyroid, cricoid and greater part of arytenoid composed
Single Paired
of hyaline Cricoid  Corniculate
 cartilage and may undergo mottled
calcification with advancing age. Arytenoid
 Thyroid 
 Epiglottis  Cuneiform
 Tritate

7. EPIGLOTTIS

8. Epiglottis
 Thin leaf like plate of elastic fibrocartilage
projects obliquely upward behind the tongue
and hyoid body and in front of laryngeal inlet
Free end Attached part
 Broad and  Long and narrow
notched in  Connected to elastic
midline thyroepiglottic
ligament
Sides: Attached to arytenoids by
aryepiglottic folds

10.  Anterior surface : Covered by mucosa (non
keratinised stratified squamous) reflect to tongue
as median glossoepiglottic fold and pharynx as two
lateral glossoepiglottic fold
 Post surface : Covered by ciliated respiratory
mucosa. Tubercle of the epiglottis.

11.  Valleculae : Depression on each side of median fold.
Common sites for impaction of sharp swallowed objects.
 Pitted by small mucous glands Perforated by branches
of internal laryngeal nerve and fibrous tissue, to be
continue with pre – epiglottic space.

12. Function of epiglottis
 During Deglutition
Hyoid bone move upward and forward
Epiglottis is bent posteriorly on laryngeal inlet
Food bolus slips over its ant surface to reach in piriform fossa
which constitute lateral food passage
 Sense of taste
 Assist in phonation
 Gag reflex
 Prevent aspiration of food into the trachea

13. Thyroid cartilage
 Largest of laryngeal cartilage
 Consist of 2 quadrilateral
laminae, fuse along their
inferior two third anteriorly to
form laryngeal prominence
 Above laminae separated by V
shaped superior thyroid notch or
incisure
 Posteriorly – Lamina diverge as
slender horns
 Superior cornua
 Inferior cornua

14. Thyroid cont…
 Internal surface and lamina – Smooth
 Angle between laminae provide attachment
to:
Thyroepiglottic ligament
paired (vestibular and vocal ligaments)
Thyoarytenoid
thyroepiglottic and vocal muscle
Anteriorly – connected to cricoid cartilage
by anterior (median) cricothyroid ligament
(thickened portion of cricothyroid
membrane)

15.  Ant. Border of laminae fuse at
angle of 90º in males and 120º in
female.
 Shallower angle in men
– Large laryngeal prominence( Adams apple)
– Greater length of vocal cords
– Deeper pitch

17. The oblique line provide the attachment
of the :
1.Thyrohyoid
2.Inferior constrictor of the pharynx

18. Cricoid cartilage
 Attached below to trachea and articulate with
thyroid cartilage and two arytenoid cartilage by
synovial joints.
 Only laryngeal cartilage to form a complete ring
 Smaller but thicker & stronger than thyroid

19. Arch Lamina
• Ant. narrow, curved •Posteriorly broad flattened
•Cricothyroid and deeper •Bears median vertical ridge
cricopharyngeous attached to •Fasciculi of longitudinal layer of
ext. aspect oesophageal muscle attached by a
tendon to upper part of ridge

20. Joints
 Cricothyroid
 Cricoarytenoid
 Arytenocorniculate
All are synovial joints

21. Ligaments and Membranes
Extrinsic ligament and membranes
 Thyrohyoid membrane
– Extends from superior border and superior cornua of thyroid to
superior margin of body and greater cornua of hyoid
– Thicker part is median thyrohyoid ligament
– Pierced by the internal laryngeal nerve and superior laryngeal
vessels
 Hyoepiglottic ligament
 Cricotracheal ligament
 Thyroepiglottic ligament

25.  Intrinsic ligaments and membranes
 Part of the fibroelastic membrane of the larynx :-
 Quadrate membrane- part above the sinus. From
the arytenoid cartilage to epiglottis.
lower free border – vestibular ligament which underlies
the vestibular fold (false cord)
upper border – aryepiglottic fold
 Conus elasticus(crico vocal membrane) :
ant part – thick known as criothyroid ligament
upper free border – vocal fold

27. Laryngeal cavity
 Extends from laryngeal inlet down to lower
border of cricoid cartilage where it continues
into trachea
 By paired upper and lower mucosal fold
projecting into lumen laryngeal cavity is divided
into
Upper(Vestibule) Middle( sinus of larynx) Lower(infraglottic)
 Upper fold : Vestibular fold guarding rima vestibuli.
 Lower fold – Vocal fold guarding rima glottidis

29. Laryngeal inlet or aditius- looks backwards and
upwards.
Anterior- epiglottis
Posterior- interarytenoid fold of mucous membrane
Each side- aryepiglottic fold

30. Saccule of larynx- Anterior part of the sinus is prolonged
upwards as a divericulum between the vestibular fold and
lamina of thyroid cartilage.
 Vocal Cords and ligaments
Free thickened upper edge of cricovocal membrane – vocal
ligament
When covered by mucosa – vocal fold ( true vocal cord )
Reinke’s Edema
Any tissue swelling below vocal cords exaggerates potential space
deep to mucosa causing accumulation of ECF and flabby swelling of
vocal cord.

31. Diff. position of vocal cords and
arytenoid cartilages

33. Muscle of Larynx
 Extrinsic : Connect larynx to neighbouring structures
Infrahyoid strap muscles i.e. thyrohyoid, sternothyroid,
sternohyoid, inf. Constrictor of pharynx
 Intrinsic muscle
– Oblique arytenoid and aryepiglottic muscle
– Transverse (inter arytenoid)
– Posterior cricorytenoid
– Lateral cricoarytenoid
– Cricothyroid

34. Muscle Actions
 Elevation of larynx- thyrohyoid, mylohyoid
 Depression of larynx- sternothyroid, sternohyoid
 Abductors – Posterior cricoarytenoid
 Adductor - Lateral cricoarytenoid, interarytenoid
 Sphincter to vestibuli – Aryepiglottics, thyroepiglottics
 Regulation of cord tension
– Cricothyroid (Tensor)
– Thyroarytenoid – (Relaxors)
– Vocalis (fine adjustment)

36. Infant Larynx
 1/3 size of adult, though it is proportionately larger.
Cavity – short and funnel shaped
 Lumen is disproportionately narrower
 Lies high in neck
 At rest – Upper border of epiglottis at 2nd / 3rd cervical vertebrae, on
elevation – reach upto 1st cervical vertebrae
 This high position – Ability to use nasal airway to breathe and
suckling

37.  Epiglottis –
X shaped with furled petiole laryngeal cartilages are softer and
more pliable
Predispose to airway collapse in inspiration
Thyroid cartilage – Shorter and broader
 Cricoid cartilage – Same shape
 Vocal cords – 4-4.5 mm long, relatively short
 Narrowest part of larynx – Subglottis
One size smaller ETtube should be ready along with the ETtube
calculated for the age.
 Unlike adults, neonatal subglottic cavity extends
posteriorly as well a inferiorly which is important to
consider when passing ET tube.

38.  Blood Supply
– Mainly from Superior and Inferior laryngeal arteries.

39.  Superior laryngeal A
Branch of sup. Thyroid A – Br. Of ext. carotid artery
In 15% cases directly from ext. carotid A.
Run’s down towards larynx with internal branch of sup. laryngeal N.
lying above it. Enter the larynx by penetrating thyrohyoid membrane.
Supplies larynx above the vocal fold.
 Inferior laryngeal A
Smaller than sup. Laryngeal A
Br. Of inf. Thyroid A – Arises from thyrocervical trunk of subclavin A.
Ascends on trachea with recurrent laryngeal N
Enter larynx at lower border of inf. Constrictor muscles.
Supplies larynx below vocal folds.
 Cricothyroid A – Arises from sup. Thyroid A.

40.  Venous supply
– Sup. and inf. Laryngeal vein
– Sup. laryngeal vein – sup thyroid V – Int. Jugular
V.
– Inf. Laryngeal vein – Inf. Thyroid V – Lt.
brachiocephalic vein

41. Lymphatic supply
 Above vocal cords
Upper deep cervical lymph nodes
 Below vocal cords
Some into
 Prelaryngeal (delphian)
 Pretrachial
Other
 Lower deep cervical lymph nodes

42. Nerve Innervation
 Epiglottis
 Rest of larynx
– Pharyngeal surface -: Glossopharyngeal
 Sensory
 nerve
Above vocal cords – Internal branch of sup laryngeal N.

– Below vocal cords - Recurrent laryngeal nerve
Laryngeal surface -: Vagus nerve
 Motor
Stimulation of laryngeal side of epiglottis during
 All muscles of larynx are supplied by recurrent laryngeal
laryngoscopy with Miller’s blade may produce vagally
nerve except cricothyroid which is supplied by external
related reactions –
branch of superior laryngeal nerve.
Laryngospasm, Bradycardia, hypertension

44. Sup. Laryngeal N. : Arises form middle and inf.
Vagal ganglion
Int. laryngeal N. Ext. laryngeal N
• Pierces thyrohyoid membrane • Continue downwad on lat. Surface of
• Sup. Br. – Mucosa of piriform fossa inf. Constrictor
• Middle Br – Musoca of ventricle • Close relationship to Sup. Thyroid
• Inf. Br. Mucosa of subglottic cavity Artery where art is clamped during
thyroid lobectomy

45. Recurrent laryngeal nerve
 Close and variable relationship to inf.
thyroid artery
 May pass in front or behind or parallel to
artery
 Ant. Br. – Motor
 Post Br. – Sensory

47.  Rt. Side
– Leaves the vagus, at level of Rt. Subclavian A. then loops
under the art & ascend to larynx in trancheoesophageal
groove
 Left side
– Originates from vagus at level of aortic arch nerve passes
under the arch to reach tracheoesphageal groove.
Unusual anomaly
 Non recurrent laryngeal nerve
 Freg. 0.3 – 1%
 Only Rt. Side affected
 Always associated with abnormal origin of Rt. Subclavian A
from aortic arch on left side.

48. CLINICAL IMPORTANCE

49. Subglottic Stenosis
Congenital malformation of cricoid
 Other reasons
cartilage resulting in severe
 Trauma
narrowing of subglottic airway and
 Scarring after prolonged endotracheal
respiratory obstruction.
intubation (in premature babies and in I.C.U.)

50. Laryngocoele
Obstruction of ventricular aditus by inflammation,
scarring, tumor
Mucous filled cavity (laryngocoele)
Expansion
Into paraglottic space Through thyrohyoid
and aryepiglottic space membrane to present as a
(internal laryngocoele) lump in neck (external
laryngocoele)

51. Injuries of the laryngeal nerves
 Ext. br. of superior laryngeal nerve- descends
over the inferior constrictor muscle of the pharynx immediately
deep to the superior thyroid artery and vein as these pass to
the superior pole of the gland; at this site the nerve may be
damaged in securing these vessels.
Paralysis of cricothyroid- hoarseness which is
compensatory

52.  Causes of rec. laryngeal nerve injury
 Close relation to the inferior thyroid artery. On the
left side more likely to lie posterior to the artery.
 Thyroidectomy
 Malignant and benign enlargement of thyroid gland
 Enlarged lymph nodes
 Cervical trauma
Left RLN : May be involved in thoracic causes
 Malignant tumor of lung, oesophagus, malignant node
 Mitral stenosis
 Compression between Lt. pulmonary artery (pushed
forward by greately enlarged Lt. Atrium) and aortic
arch
 Following ligation of PDA

53. U/L complete paralysis of Rec. L.N.
 Asymptomatic or having hoarse voice
 Hoarseness may be permanent or become less
severe with time as healthy cord hyper-adduct and
appose paralysed cord.
 No risk of aspiration
B/L R.L.N. Paralysis
 Complete loss of vocal power
 Vocal folds in cadaveric position (in btw adduction
and abduction)
 Valve like obstruction(esp during inspiration)
-dyspnea & marked inspiratory stridor.

54. Respiratory obstruction after thyroidectomy-
 direct trauma to the tracheal cartilages (especially in
carcinoma of the thyroid) causing tracheomalacia.
 Haemorrhage into the neck deep to the investing fascia,
causing external pressure on the trachea.Haemorrhage into
an intact gland is more likely to obstruct the airway by
producing laryngeal oedema than by direct compression.
 If the tracheal cartilages have not been damaged,very
unusual for a benign enlarged thyroid to compress the trachea
to an extent that prevents tracheal intubation. The trachea
invariably straightens and dilates during intubation.
Laryngoscopy within 24 h of thyroidectomy often reveals some
degree of oedema of the false cords, presumably as a result
of external laryngeal trauma during the operation and damage
to venous and lymphatic drainage channels.

55. CRICOTHYROTOMY
 ‘ Surgical’ airway via the cricothyroid membrane
in acute emergency when obsruction at or
above the larynx not relieved.
 Patient positon: supine and the neck in the
neutral position or (in the absence of cervical
spine injury) in extension

56. Cricothyrotomy is relatively easy to perform and
should (in theory at least) be associated with minimal
blood loss, as the cricothyroid membrane is thought to
be largely avascular

57. Laryngoscopic anatomy
 To view larynx
– Mouth, oropharynx and larynx must be in one
plane
Flexion at the
Extension at atlanto
occipital joint joint
atlantoaxial .
sniffing position
Like moving the head forward to take 1st sip from a glass of
water full to the brim.

59. Structures Visible
 Base of tongue
 Valleculae
 Ant. Surface of epiglottis
 Laryngeal aditus
Front - post. Aspect of epiglottis
Aryepiglotic fold on each side post. Medially
 Vocal Cords
Pale, glistening, ribbon, extending from angle of thyroid cartilage
backwards to vocal process of arytenoids

60. AIRWAY BLOCKS
 General Indications :
 Before anesthetic induction in patients with airway
compromise, trauma to the upper airway, or cervical
instability.
 To abolish or blunt reflexes such as laryngospasm,
coughing, and other undesirable cardiovascular reflexes that
often occur during procedures that involve manipulation of the
airway (awake laryngoscopy, nasal intubation, and fiberoptic
intubation).
 To provide patient comfort and airway anesthesia during
the performance of these procedures.

61. SUPERIOR LARYNGEAL NERVE
BLOCK
 Indications: To block the internal (sensory) branch of the
SLN, resulting in abolition of the gag reflex or hemodynamic
responses to laryngoscopy or bronchoscopy.
 Drugs: 2-4 ml of Lidocaine 1% or 2% lidocaine, with or without
epinephrine.
 Patient Position: Supine, with head slightly extended.

64. GLOSSOPHARYNGEAL NERVE
BLOCK
 When topical techniques are not completely effective in
obliterating the gag reflex. This block can be performed after
the mouth and oropharynx are adequately anesthetized.
Branches of this nerve are most easily accessed as they
transverse the palatoglossal folds

66.  A posterior approach
(*often used for
tonsillectomy), may be
difficult, in visualizing
the site for needle
insertion, which is
behind the
palatopharyngeal arch
(where the nerve is in
close proximity to the
carotid artery). There is
risk for arterial
injection and bleeding

67. RECURRENT LARYNGEAL
NERVE
BLOCK( TRANSTRACHEAL/
 Indications : Transtracheal injection performed to block the
TRANSLARYNGEAL) laryngoscopy, fiberoptic
recurrent laryngeal nerve for awake
and/or retrograde intubation. Abolition of the gag reflex or
hemodynamic responses to laryngoscopy or bronchoscopy.
Used to help avoid Valsalva-like straining that may follow
other "awake" intubations (patient is sedated and
spontaneously ventilating).
 Drugs: Most often, 3-4 ml of Lidocaine 4 % is used. Also,
1% or 2% lidocaine, with or without epinephrine.
 Patient Position: Supine, with neck hyperextended (or
Position
pillow removed and extended).

68. Placement of
fingers to
identify the
midline of the
cricothyroid
membrane

69. Placement
of needle

70. Transtrachea
l spread of
local
anaesthetic
with
coughing

71. Thank You.