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

Anatomy of larynx and its anaesthetic importance

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Page 1: Anatomy of larynx and its anaesthetic importance

ANATOMY OF LARYNX ANATOMY OF LARYNX

AND ITS ANAESTHETIC AND ITS ANAESTHETIC

IMPORTANCE IMPORTANCE

Presented by Presented by

Dr Sindhu SapruDr Sindhu Sapru

Moderator Moderator

Dr. S.P MeenaDr. S.P Meena

Page 2: Anatomy of larynx and its anaesthetic importance

LarynxLarynx

An air passage, a sphincter and an An air passage, a sphincter and an

organ of phonation. organ of phonation.

Extends from root of tongue to trachea Extends from root of tongue to trachea

At RestAt Rest– Lies opposite 3Lies opposite 3rdrd-6-6thth cervical vertebra in cervical vertebra in

adult male adult male – Some what higher in children( 2Some what higher in children( 2ndnd and 3 and 3rdrd

cervical vertebrae) and femalescervical vertebrae) and females

Upto puberty – Male and female larynx Upto puberty – Male and female larynx

similar in size after that male larynx similar in size after that male larynx

enlarges considerably and continue until enlarges considerably and continue until

40 years of age. 40 years of age.

Page 3: Anatomy of larynx and its anaesthetic importance

Difference between male and Difference between male and female larynxfemale larynx

MaleMale FemaleFemale

Length Length 44 mm44 mm 36 mm36 mm

Transverse Transverse diameterdiameter

43 mm43 mm 41 mm41 mm

Sagittal diameterSagittal diameter 36 mm36 mm 26 mm26 mm

Page 4: Anatomy of larynx and its anaesthetic importance

EmbryologyEmbryology Internal lining of larynx Internal lining of larynx

EndodermEndoderm Cartilage and muscleCartilage and muscle

Mesenchyme of 4Mesenchyme of 4thth and 6 and 6thth Pharyngeal arches Pharyngeal arches Rapid proliferation of mesenchymeRapid proliferation of mesenchyme

Change in laryngeal orifice from sagittal slit to T-shaped Change in laryngeal orifice from sagittal slit to T-shaped opening opening

Transforms into thyroid, cricoid and arytenoid cartilages Transforms into thyroid, cricoid and arytenoid cartilages Rapid proliferation of epithelium Rapid proliferation of epithelium

Temporary occlusion of lumen Temporary occlusion of lumen Vacuolization and recanalization Vacuolization and recanalization Formation of laryngeal ventricles Formation of laryngeal ventricles False and true vocal cords. False and true vocal cords.

Page 5: Anatomy of larynx and its anaesthetic importance

All laryngeal muscles innervated All laryngeal muscles innervated

by 10by 10thth cranial nerve cranial nerve

Superior laryngeal N. innervate Superior laryngeal N. innervate

derivatives of 4derivatives of 4thth pharyngeal arch pharyngeal arch

Recurrent laryngeal N. innervate Recurrent laryngeal N. innervate

derivatives of 6derivatives of 6thth pharyngeal arch pharyngeal arch

Page 6: Anatomy of larynx and its anaesthetic importance

Skeleton of Larynx Skeleton of Larynx

Series of cartilages interconnected by Series of cartilages interconnected by

ligaments and fibrous membrane and ligaments and fibrous membrane and

moved by number of muscles. moved by number of muscles. Laryngeal Cartilages Laryngeal Cartilages

Single Single PairedPaired Cricoid Cricoid Thyroid Thyroid Epiglottis Epiglottis

CorniculateCorniculate Arytenoid Arytenoid Cuneiform Cuneiform Tritate Tritate

Corniculate, cuneiform, tritate, epiglottis and Corniculate, cuneiform, tritate, epiglottis and

apices of arytenoid are composed of elastic apices of arytenoid are composed of elastic

fibrocartilage with little tendancy to calcify. fibrocartilage with little tendancy to calcify.

Thyroid, cricoid and greater part of arytenoid Thyroid, cricoid and greater part of arytenoid

composed of hyaline cartilage and may undergo composed of hyaline cartilage and may undergo

mottled calcification with advancing age. mottled calcification with advancing age.

Page 7: Anatomy of larynx and its anaesthetic importance

EPIGLOTTIS

Page 8: Anatomy of larynx and its anaesthetic importance

EpiglottisEpiglottis

Thin leaf like plate of elastic fibrocartilage Thin leaf like plate of elastic fibrocartilage

projects obliquely upward behind the projects obliquely upward behind the

tongue and hyoid body and in front of tongue and hyoid body and in front of

laryngeal inlet laryngeal inlet Free end Free end Attached partAttached part Broad and Broad and

notched in notched in

midline midline

Long and narrow Long and narrow

Connected to Connected to

elastic elastic

thyroepiglottic thyroepiglottic

ligament ligament Sides: Attached to arytenoids by aryepiglottic folds

Page 9: Anatomy of larynx and its anaesthetic importance
Page 10: Anatomy of larynx and its anaesthetic importance

Anterior surface : Covered by mucosa (non

keratinised stratified squamous) reflect to

tongue as median glossoepiglottic fold and

pharynx as two lateral glossoepiglottic fold

Post surfacePost surface : Covered by ciliated : Covered by ciliated

respiratory mucosa. Tubercle of the respiratory mucosa. Tubercle of the

epiglottis.epiglottis.

Page 11: Anatomy of larynx and its anaesthetic importance

Valleculae Valleculae : : Depression on each side of median Depression on each side of median

fold. Common sites for impaction of sharp fold. Common sites for impaction of sharp

swallowed objects.swallowed objects.

Pitted by small mucous glands Perforated by Pitted by small mucous glands Perforated by

branches of internal laryngeal nerve and fibrous branches of internal laryngeal nerve and fibrous

tissue, to be continue with pre – epiglottic space. tissue, to be continue with pre – epiglottic space.

Page 12: Anatomy of larynx and its anaesthetic importance

Function of epiglottisFunction of epiglottis During DeglutitionDuring Deglutition

Hyoid bone move upward and forward Hyoid bone move upward and forward Epiglottis is bent posteriorly on laryngeal inlet Epiglottis is bent posteriorly on laryngeal inlet Food bolus slips over its ant surface to reach in piriform Food bolus slips over its ant surface to reach in piriform

fossa which constitute lateral food passagefossa which constitute lateral food passage

Sense of tasteSense of taste

Assist in phonationAssist in phonation

Gag reflexGag reflex

Prevent aspiration of food into the tracheaPrevent aspiration of food into the trachea

Page 13: Anatomy of larynx and its anaesthetic importance

Thyroid cartilage Thyroid cartilage

Largest of laryngeal cartilage Largest of laryngeal cartilage Consist of 2 quadrilateral Consist of 2 quadrilateral

laminae, fuse along their laminae, fuse along their inferior two third anteriorly inferior two third anteriorly to form laryngeal prominence to form laryngeal prominence

Above laminae separated by Above laminae separated by V shaped superior thyroid V shaped superior thyroid notch or incisurenotch or incisure

Posteriorly – Lamina diverge Posteriorly – Lamina diverge as slender horns as slender horns Superior cornua Superior cornua Inferior cornua Inferior cornua

Page 14: Anatomy of larynx and its anaesthetic importance

Internal surface and lamina – SmoothInternal surface and lamina – Smooth

Angle between laminae provide Angle between laminae provide

attachment to:attachment to:

Thyroepiglottic ligamentThyroepiglottic ligament

paired (vestibular and vocal ligaments) paired (vestibular and vocal ligaments)

ThyoarytenoidThyoarytenoid

thyroepiglottic and vocal muscle thyroepiglottic and vocal muscle

Anteriorly – connected to cricoid cartilage Anteriorly – connected to cricoid cartilage

by anterior (median) cricothyroid by anterior (median) cricothyroid

ligament (thickened portion of ligament (thickened portion of

cricothyroid membrane)cricothyroid membrane)

Thyroid cont…Thyroid cont…

Page 15: Anatomy of larynx and its anaesthetic importance

Ant. Border of laminae fuse at Ant. Border of laminae fuse at

angle of 90º in males and 120º in angle of 90º in males and 120º in

female. female.

Shallower angle in men Shallower angle in men

– Large laryngeal prominence( Adams apple)Large laryngeal prominence( Adams apple)

– Greater length of vocal cordsGreater length of vocal cords

– Deeper pitchDeeper pitch

Page 16: Anatomy of larynx and its anaesthetic importance
Page 17: Anatomy of larynx and its anaesthetic importance

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

Page 18: Anatomy of larynx and its anaesthetic importance

Cricoid cartilage Cricoid cartilage Attached below to trachea and articulate Attached below to trachea and articulate

with thyroid cartilage and two arytenoid with thyroid cartilage and two arytenoid

cartilage by synovial joints. cartilage by synovial joints.

Only laryngeal cartilage to form a complete Only laryngeal cartilage to form a complete

ringring

Smaller but thicker & stronger than thyroid Smaller but thicker & stronger than thyroid

Page 19: Anatomy of larynx and its anaesthetic importance

Arch Lamina• Ant. narrow, curved

•Cricothyroid and deeper cricopharyngeous attached to ext. aspect

•Posteriorly broad flattened

•Bears median vertical ridge

•Fasciculi of longitudinal layer of oesophageal muscle attached by a tendon to upper part of ridge

Page 20: Anatomy of larynx and its anaesthetic importance

JointsJoints

Cricothyroid Cricothyroid

Cricoarytenoid Cricoarytenoid

Arytenocorniculate Arytenocorniculate

All are synovial joints All are synovial joints

Page 21: Anatomy of larynx and its anaesthetic importance

Ligaments and Membranes Ligaments and Membranes Extrinsic ligament and membranes Extrinsic ligament and membranes

Thyrohyoid membrane Thyrohyoid membrane

– Extends from superior border and superior cornua of Extends from superior border and superior cornua of

thyroid to superior margin of body and greater cornua of thyroid to superior margin of body and greater cornua of

hyoid hyoid

– Thicker part is median thyrohyoid ligament Thicker part is median thyrohyoid ligament

– Pierced by the internal laryngeal nerve and superior Pierced by the internal laryngeal nerve and superior

laryngeal vesselslaryngeal vessels

Hyoepiglottic ligamentHyoepiglottic ligament

Cricotracheal ligamentCricotracheal ligament

Thyroepiglottic ligamentThyroepiglottic ligament

Page 22: Anatomy of larynx and its anaesthetic importance
Page 23: Anatomy of larynx and its anaesthetic importance
Page 24: Anatomy of larynx and its anaesthetic importance
Page 25: Anatomy of larynx and its anaesthetic importance

Intrinsic ligaments and membranes Intrinsic ligaments and membranes

Part of the Part of the fibroelastic membrane of the larynx :-fibroelastic membrane of the larynx :-

Quadrate membrane- Quadrate membrane- part above the sinus. part above the sinus.

From the arytenoid cartilage to epiglottis.From the arytenoid cartilage to epiglottis.

lower free border – lower free border – vestibular ligament vestibular ligament which which

underlies the vestibular fold (false cord)underlies the vestibular fold (false cord)

upper border – upper border – aryepiglottic foldaryepiglottic fold

Conus elasticus(crico vocal membrane) : Conus elasticus(crico vocal membrane) :

ant part – thick known as ant part – thick known as criothyroid ligamentcriothyroid ligament

upper free border – upper free border – vocal foldvocal fold

Page 26: Anatomy of larynx and its anaesthetic importance
Page 27: Anatomy of larynx and its anaesthetic importance

Laryngeal cavity Laryngeal cavity

Extends from laryngeal inlet down to lower Extends from laryngeal inlet down to lower

border of cricoid cartilage where it border of cricoid cartilage where it

continues into tracheacontinues into trachea

By paired upper and lower mucosal fold By paired upper and lower mucosal fold

projecting into lumen laryngeal cavity is projecting into lumen laryngeal cavity is

divided intodivided into

Upper(Vestibule) Middle( sinus of larynx)

Lower(infraglottic)

Upper fold : Vestibular fold guarding rima Upper fold : Vestibular fold guarding rima vestibuli. vestibuli.

Lower fold – Vocal fold guarding rima glottidis Lower fold – Vocal fold guarding rima glottidis

Page 28: Anatomy of larynx and its anaesthetic importance
Page 29: Anatomy of larynx and its anaesthetic importance

Laryngeal inlet or aditius- Laryngeal inlet or aditius- lookslooks backwards backwards

and upwards.and upwards.

Anterior- epiglottisAnterior- epiglottis

Posterior- interarytenoid fold of mucous Posterior- interarytenoid fold of mucous

membranemembrane

Each side- aryepiglottic foldEach side- aryepiglottic fold

Page 30: Anatomy of larynx and its anaesthetic importance

Saccule of larynx- Saccule of larynx- Anterior part of the sinus is Anterior part of the sinus is

prolonged upwards as a divericulum between the prolonged upwards as a divericulum between the

vestibular fold and lamina of thyroid cartilage. vestibular fold and lamina of thyroid cartilage.

Vocal Cords and ligamentsVocal Cords and ligaments

Free thickened upper edge of cricovocal membrane Free thickened upper edge of cricovocal membrane

– vocal ligament – vocal ligament

When covered by mucosa – vocal fold ( true vocal When covered by mucosa – vocal fold ( true vocal

cord )cord )

Reinke’s EdemaReinke’s Edema

Any tissue swelling below vocal cords exaggerates Any tissue swelling below vocal cords exaggerates

potential space deep to mucosa causing accumulation of potential space deep to mucosa causing accumulation of

ECF and flabby swelling of vocal cord. ECF and flabby swelling of vocal cord.

Page 31: Anatomy of larynx and its anaesthetic importance

Diff. position of vocal cords and Diff. position of vocal cords and arytenoid cartilages arytenoid cartilages

Page 32: Anatomy of larynx and its anaesthetic importance
Page 33: Anatomy of larynx and its anaesthetic importance

Muscle of LarynxMuscle of Larynx

Extrinsic : Connect larynx to neighbouring structures Extrinsic : Connect larynx to neighbouring structures

Infrahyoid strap muscles i.e. thyrohyoid, Infrahyoid strap muscles i.e. thyrohyoid,

sternothyroid, sternohyoid, inf. Constrictor of pharynx sternothyroid, sternohyoid, inf. Constrictor of pharynx

Intrinsic muscle Intrinsic muscle

– Oblique arytenoid and aryepiglottic muscleOblique arytenoid and aryepiglottic muscle

– Transverse (inter arytenoid)Transverse (inter arytenoid)

– Posterior cricorytenoidPosterior cricorytenoid

– Lateral cricoarytenoid Lateral cricoarytenoid

– Cricothyroid Cricothyroid

Page 34: Anatomy of larynx and its anaesthetic importance

Muscle Actions Muscle Actions Elevation of larynx- thyrohyoid, mylohyoidElevation of larynx- thyrohyoid, mylohyoid

Depression of larynx- sternothyroid, sternohyoidDepression of larynx- sternothyroid, sternohyoid

Abductors – Posterior cricoarytenoid Abductors – Posterior cricoarytenoid

Adductor - Lateral cricoarytenoid, interarytenoid Adductor - Lateral cricoarytenoid, interarytenoid

Sphincter to vestibuli – Aryepiglottics, Sphincter to vestibuli – Aryepiglottics,

thyroepiglotticsthyroepiglottics

Regulation of cord tension Regulation of cord tension

– Cricothyroid (Tensor)Cricothyroid (Tensor)

– Thyroarytenoid – (Relaxors)Thyroarytenoid – (Relaxors)

– Vocalis (fine adjustment) Vocalis (fine adjustment)

Page 35: Anatomy of larynx and its anaesthetic importance
Page 36: Anatomy of larynx and its anaesthetic importance

Infant Larynx Infant Larynx 1/3 size of adult, though it is proportionately larger. 1/3 size of adult, though it is proportionately larger.

Cavity – short and funnel shapedCavity – short and funnel shaped

Lumen is disproportionately narrowerLumen is disproportionately narrower

Lies high in neck Lies high in neck

At rest – Upper border of epiglottis at 2At rest – Upper border of epiglottis at 2ndnd / 3 / 3rdrd cervical cervical

vertebrae, on elevation – reach upto 1vertebrae, on elevation – reach upto 1stst cervical vertebrae cervical vertebrae

This high position – Ability to use nasal airway to breathe This high position – Ability to use nasal airway to breathe

and suckling and suckling

Page 37: Anatomy of larynx and its anaesthetic importance

Epiglottis – Epiglottis –

X shaped with furled petiole laryngeal cartilages are X shaped with furled petiole laryngeal cartilages are

softer and more pliable softer and more pliable

Predispose to airway collapse in inspirationPredispose to airway collapse in inspiration

Thyroid cartilage – Thyroid cartilage – Shorter and broader Shorter and broader Cricoid cartilage – Cricoid cartilage – Same shape Same shape Vocal cords – Vocal cords – 4-4.5 mm long, relatively short4-4.5 mm long, relatively short Narrowest part of larynx – Subglottis Narrowest part of larynx – Subglottis

One size smaller ETtube should be ready along with the One size smaller ETtube should be ready along with the ETtube calculated for the ageETtube calculated for the age. .

Unlike adults, neonatal subglottic cavity Unlike adults, neonatal subglottic cavity extends posteriorly as well a inferiorly which is extends posteriorly as well a inferiorly which is important to consider when passing ET tube. important to consider when passing ET tube.

Page 38: Anatomy of larynx and its anaesthetic importance

Blood Supply Blood Supply

– Mainly from Superior and Inferior laryngeal Mainly from Superior and Inferior laryngeal

arteries. arteries.

Page 39: Anatomy of larynx and its anaesthetic importance

Superior laryngeal ASuperior laryngeal A

Branch of sup. Thyroid A – Br. Of ext. carotid artery Branch of sup. Thyroid A – Br. Of ext. carotid artery

In 15% cases directly from ext. carotid A.In 15% cases directly from ext. carotid A.

Run’s down towards larynx with internal branch of sup. Run’s down towards larynx with internal branch of sup.

laryngeal N. lying above it. Enter the larynx by penetrating laryngeal N. lying above it. Enter the larynx by penetrating

thyrohyoid membrane. thyrohyoid membrane.

Supplies larynx above the vocal fold.Supplies larynx above the vocal fold.

Inferior laryngeal A Inferior laryngeal A

Smaller than sup. Laryngeal ASmaller than sup. Laryngeal A

Br. Of inf. Thyroid A – Arises from thyrocervical trunk of Br. Of inf. Thyroid A – Arises from thyrocervical trunk of

subclavin A. subclavin A.

Ascends on trachea with recurrent laryngeal NAscends on trachea with recurrent laryngeal N

Enter larynx at lower border of inf. Constrictor muscles.Enter larynx at lower border of inf. Constrictor muscles.

Supplies larynx below vocal folds. Supplies larynx below vocal folds.

Cricothyroid A Cricothyroid A – Arises from sup. Thyroid A. – Arises from sup. Thyroid A.

Page 40: Anatomy of larynx and its anaesthetic importance

Venous supply Venous supply

– Sup. and inf. Laryngeal veinSup. and inf. Laryngeal vein

– Sup. laryngeal vein – sup thyroid V – Int. Sup. laryngeal vein – sup thyroid V – Int.

Jugular V. Jugular V.

– Inf. Laryngeal vein – Inf. Thyroid V – Lt. Inf. Laryngeal vein – Inf. Thyroid V – Lt.

brachiocephalic vein brachiocephalic vein

Page 41: Anatomy of larynx and its anaesthetic importance

Lymphatic supply Lymphatic supply

Above vocal cords Above vocal cords

Upper deep cervical lymph nodes Upper deep cervical lymph nodes

Below vocal cords Below vocal cords

Some into Some into Prelaryngeal (delphian)Prelaryngeal (delphian)

Pretrachial Pretrachial

Other Other Lower deep cervical lymph nodes Lower deep cervical lymph nodes

Page 42: Anatomy of larynx and its anaesthetic importance

Nerve Innervation Nerve Innervation EpiglottisEpiglottis

– Pharyngeal surface -: Pharyngeal surface -:

Glossopharyngeal nerveGlossopharyngeal nerve

– Laryngeal surface -: Laryngeal surface -: Vagus nerveVagus nerve

Stimulation of laryngeal side of epiglottis during

laryngoscopy with Miller’s blade may produce

vagally related reactions –

Laryngospasm, Bradycardia, hypertension

Rest of larynx

SensorySensory

Above vocal cords – Internal branch of sup Above vocal cords – Internal branch of sup

laryngeal N. laryngeal N.

Below vocal cords - Recurrent laryngeal nerveBelow vocal cords - Recurrent laryngeal nerve

MotorMotor

All muscles of larynx are supplied by recurrent All muscles of larynx are supplied by recurrent

laryngeal nerve except laryngeal nerve except cricothyroid cricothyroid which is which is

supplied by supplied by external branch of superior laryngeal external branch of superior laryngeal

nervenerve..

Page 43: Anatomy of larynx and its anaesthetic importance
Page 44: Anatomy of larynx and its anaesthetic importance

Sup. Laryngeal N. : Arises form middle Sup. Laryngeal N. : Arises form middle and inf. and inf.

Vagal ganglion Vagal ganglion

Int. laryngeal N.

Ext. laryngeal N

• Pierces thyrohyoid membrane

• Sup. Br. – Mucosa of piriform fossa

• Middle Br – Musoca of ventricle

• Inf. Br. Mucosa of subglottic cavity

• Continue downwad on lat.

Surface of inf. Constrictor

• Close relationship to Sup.

Thyroid Artery where art is

clamped during thyroid

lobectomy

Page 45: Anatomy of larynx and its anaesthetic importance

Recurrent laryngeal nerveRecurrent laryngeal nerve

Close and variable relationship to inf. Close and variable relationship to inf.

thyroid arterythyroid artery

May pass in front or behind or May pass in front or behind or

parallel to artery parallel to artery

Ant. Br. – MotorAnt. Br. – Motor

Post Br. – Sensory Post Br. – Sensory

Page 46: Anatomy of larynx and its anaesthetic importance
Page 47: Anatomy of larynx and its anaesthetic importance

Rt. Side Rt. Side – Leaves the vagus, at level of Rt. Subclavian A. then Leaves the vagus, at level of Rt. Subclavian A. then

loops under the art & ascend to larynx in loops under the art & ascend to larynx in trancheoesophageal groovetrancheoesophageal groove

Left side Left side – Originates from vagus at level of aortic arch nerve Originates from vagus at level of aortic arch nerve

passes under the arch to reach tracheoesphageal passes under the arch to reach tracheoesphageal groove.groove.

Unusual anomalyUnusual anomaly

Non recurrent laryngeal nerveNon recurrent laryngeal nerve

Freg. 0.3 – 1%Freg. 0.3 – 1%

Only Rt. Side affected Only Rt. Side affected

Always associated with abnormal origin of Rt. Always associated with abnormal origin of Rt.

Subclavian A from aortic arch on left side. Subclavian A from aortic arch on left side.

Page 48: Anatomy of larynx and its anaesthetic importance

CLINICAL IMPORTANCECLINICAL IMPORTANCE

Page 49: Anatomy of larynx and its anaesthetic importance

Subglottic StenosisSubglottic Stenosis

Congenital malformation of Congenital malformation of

cricoid cartilage resulting in cricoid cartilage resulting in

severe narrowing of subglottic severe narrowing of subglottic

airway and respiratory airway and respiratory

obstruction.obstruction.

Other reasonsOther reasons

TraumaTrauma

Scarring after prolonged endotracheal Scarring after prolonged endotracheal

intubation (in premature babies and in intubation (in premature babies and in

I.C.U.)I.C.U.)

Page 50: Anatomy of larynx and its anaesthetic importance

LaryngocoeleLaryngocoeleObstruction of ventricular aditus by Obstruction of ventricular aditus by

inflammation, inflammation, scarring, tumor scarring, tumor

Mucous filled cavity (laryngocoele) Mucous filled cavity (laryngocoele)

Expansion Expansion

Into paraglottic Into paraglottic space and space and

aryepiglottic space aryepiglottic space (internal (internal

laryngocoele)laryngocoele)

Through thyrohyoid Through thyrohyoid membrane to present as membrane to present as a lump in neck (external a lump in neck (external

laryngocoele)laryngocoele)

Page 51: Anatomy of larynx and its anaesthetic importance

Injuries of the laryngeal nervesInjuries of the laryngeal nerves Ext. br. of superior laryngeal nerve- 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

Page 52: Anatomy of larynx and its anaesthetic importance

Causes of rec. laryngeal nerve injuryCauses 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 Thyroidectomy

Malignant and benign enlargement of thyroid gland Malignant and benign enlargement of thyroid gland

Enlarged lymph nodesEnlarged lymph nodes

Cervical trauma Cervical trauma

Left RLN : May be involved in thoracic causesLeft RLN : May be involved in thoracic causes

Malignant tumor of lung, oesophagus, malignant node Malignant tumor of lung, oesophagus, malignant node

Mitral stenosis Mitral stenosis

Compression between Lt. pulmonary artery Compression between Lt. pulmonary artery

(pushed forward by greately enlarged Lt. Atrium) (pushed forward by greately enlarged Lt. Atrium)

and aortic archand aortic arch

Following ligation of PDAFollowing ligation of PDA

Page 53: Anatomy of larynx and its anaesthetic importance

U/L complete paralysis of Rec. L.N. U/L complete paralysis of Rec. L.N. Asymptomatic or having hoarse voice Asymptomatic or having hoarse voice Hoarseness may be permanent or become less Hoarseness may be permanent or become less

severe with time as healthy cord hyper-adduct severe with time as healthy cord hyper-adduct and appose paralysed cord.and appose paralysed cord.

No risk of aspiration No risk of aspiration

B/L R.L.N. Paralysis B/L R.L.N. Paralysis Complete loss of vocal powerComplete loss of vocal power Vocal folds in cadaveric position (in btw Vocal folds in cadaveric position (in btw

adduction and abduction)adduction and abduction) Valve like obstruction(esp during inspiration) -Valve like obstruction(esp during inspiration) -

dyspnea & marked inspiratory stridor.dyspnea & marked inspiratory stridor.

Page 54: Anatomy of larynx and its anaesthetic importance

Respiratory obstruction after thyroidectomy- 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.HHaemorrhage into an intact gland is more likely to obstruct the airway by into an intact gland is more likely to obstruct the airway by producing laryngeal oedema than by direct compression.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.

Page 55: Anatomy of larynx and its anaesthetic importance

CRICOTHYROTOMYCRICOTHYROTOMY

‘‘Surgical’ airway via the cricothyroid Surgical’ airway via the cricothyroid membrane in acute emergency when membrane in acute emergency when obsruction at or above the larynx not obsruction at or above the larynx not relieved.relieved.

Patient positon: supine and the neck in the Patient positon: supine and the neck in the neutral position or (in the absence of neutral position or (in the absence of cervical spine injury) in extensioncervical spine injury) in extension

Page 56: Anatomy of larynx and its anaesthetic importance

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

Page 57: Anatomy of larynx and its anaesthetic importance

Laryngoscopic anatomy Laryngoscopic anatomy To view larynx To view larynx

– Mouth, oropharynx and larynx must be Mouth, oropharynx and larynx must be

in one planein one plane

Flexion at the

atlantoaxial

joint

Like moving the head forward to take 1st sip from a glass of water full to the brim.

Extension at atlanto

occipital joint .

sniffing position

Page 58: Anatomy of larynx and its anaesthetic importance
Page 59: Anatomy of larynx and its anaesthetic importance

Structures Visible Structures Visible

Base of tongueBase of tongue

ValleculaeValleculae

Ant. Surface of epiglottis Ant. Surface of epiglottis

Laryngeal aditus Laryngeal aditus

Front - post. Aspect of epiglottis Front - post. Aspect of epiglottis

Aryepiglotic fold on each side post. Medially Aryepiglotic fold on each side post. Medially

Vocal CordsVocal Cords

Pale, glistening, ribbon, extending from angle of thyroid Pale, glistening, ribbon, extending from angle of thyroid

cartilage backwards to vocal process of arytenoids cartilage backwards to vocal process of arytenoids

Page 60: Anatomy of larynx and its anaesthetic importance

AIRWAY BLOCKSAIRWAY 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.

Page 61: Anatomy of larynx and its anaesthetic importance

SUPERIOR LARYNGEAL NERVE SUPERIOR LARYNGEAL NERVE BLOCKBLOCK

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.Patient Position: Supine, with head slightly extended.

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GLOSSOPHARYNGEAL NERVE GLOSSOPHARYNGEAL NERVE BLOCKBLOCK

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

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

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RECURRENT LARYNGEAL NERVE RECURRENT LARYNGEAL NERVE BLOCK( TRANSTRACHEAL/ BLOCK( TRANSTRACHEAL/ TRANSLARYNGEAL)TRANSLARYNGEAL) IndicationsIndications: : Transtracheal injection performed to block

the recurrent laryngeal nerve for awake laryngoscopy, fiberoptic 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: Drugs: Most often, 3-4 ml of Lidocaine 4 % is used. Also, 1% or 2% lidocaine, with or without epinephrine.

Patient PositionPatient Position: Supine, with neck hyperextended (or pillow removed and extended).

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Placement of fingers to identify the midline of the cricothyroid membrane

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Placement of needle

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Transtracheal spread of local anaesthetic with coughing

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Thank You.Thank You.