LARYNX

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INTRODUCTION Respiratory organ modified to produce soundSynonym: Voice box,organ of phonationAnterior midline of upper neck infront of

laryngopharynxExtent:upper border of epiglottis to lower

border of cricoid.Lies:infront of C3-C6

Male larynxV=44mm,T=43 mm,AP=36mm

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FUNCTIONSPhonation

Respiration

Protection

Deglutition

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DEVELOPMENT

• Laryngotracheal groove (caudal end of ventral wall of primitive pharynx- 28 days of development)

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DEVELOPMENT

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• Epithelium & glands--endodermal lining• Laryngeal cartilages-from mesenchyme ie derived

from neural crest cells• 4th arch-thyroid,cunieform,corniculate• 5th arch-cricoid• 6th arch-arytenoid• 2 and 3 arch –hyoid bone• Epiglottis- caudal part of hypobranchial eminence• Muscles- 4 & 6 arches(Cricothyroid, Extrinsic=4th)• Muscle cells-myotomes of cranial somites

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SKELETON OF LARYNX

Cartilages

Joints

Membranes & ligaments

Muscles

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CARTILAGES

Paired • Arytenoid

• Corniculate

• Cunieform

• Cartilago triticea

Unpaired • Thyroid

• Cricoid

• Epiglottis

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THYROID CARTILAGE

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Cricoid cartilage

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Epiglottis

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Corniculate cartilage of Santorini

Cunieform cartilage of Wrisberg

Arytenoid cartilage

• Hyaline cartilages:

Thyroid, Cricoid, basal part& muscular process of Arytenoid

• Elastic fibrocartilage: Epiglottis,Corniculate,Cunieform,apices & vocal process of Arytenoids

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JOINTS:

• Cricothyroid joint- Between inferior horn of thyroid and cricoid- Synovial hinge- Rocking movements{ Transverse

axis}

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• Cricoarytenoid joint– Plane synovial– Movements:

• Sliding• Rotatory

• Arytenocorniculate

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MEMBRANES & LIGAMENTSExtrinsic

• Thyrohyoid

• Cricothyroid

• Cricotracheal

• Thyroepiglottic

• Hyoepiglottic

Intrinsic

• Quadrangular membrane & vestibular ligament

• Cricovocal membrane & vocal ligament

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Extrinsic

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Extrinsic

Intrinsic-Quadrate membrane

Boundaries:– Sup : aryepiglottic folds– Ant : lat margin of epiglottis– Post : arytenoid and corniculate

cartilage– Inf : free called as vestibular fold– Covered by mucous membrane to Form

“False vocal folds”

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Cricothyroid ligament

– Median cricothyroid lig : • Thickened membrane• Pass from upper border of cricoid to lower border of thyroid

– Lateral cricothyroid lig : (cricovocal membrane)

• Attachments– Project up from arch of cricoid to

» Anteriorly : Jn of thyroid lamina» Posteriorly: vocal pr of arytenoid

– Cricovocal memb free b/t ant & post attachment is thick

– Form CV ligament, when covered with mucous memb : form true Vocal cords

Conus elasticus : commonly includes all parts of the lig or just the anterior part of VC

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Intrinsic

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Extrinsic• Attached to hyoid, thyroid• Depressors – infrahyoid• Elevators as below

Extrinsic attached to hyoid– Geniohyoid– Mylohyoid– Digastric, ant and post belly

– Stylohyoid– Thyrohyoid

Extrinsic attached to thyroid– Palatopharyngeus– Salpingopharyngeus– stylopharyngeus

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Intrinsic• Acts on VC• Acts on epiglottis

Muscles acting on VC– Length and tension

• Cricothyroid• Thyroarytenoids

– Abductor• Post cricoarytenoid

– Adductors• Lateral cricoarytenoid• Thyroarytenoid• Interarytenoideus

Muscles acting on epiglottis– Aryepiglotticus– Thyroepiglotticus

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MUSCLES OF LARYNX Extrinsic Intrinsic

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Extrinsic

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Intrinsic

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INTRINSIC MUSCLE OF LARYNX

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EXCEPTIONS

• Cricothyroid -> only muscle lying on outer aspect of larynx

• Transverse arytenoid-> only intrinsic muscle of larynx which is unpaired

• All intrinsic muscles adduct vocal cords except post cricoarytenoid

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SUBDIVISIONS OF LARYNGEAL CAVITY

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inlet– Boundaries

• Ant : epiglottis• Post : arytenoid cart• Sides : aryepiglottic folds

Vestibule– Space b/t inlet & vestibular folds– Laterally : quadrate membrane– Ant : epiglottis– Lower : Rima of vestibule

False vocal cords– Vestibular folds– Rima vestibuli (b/t vestibular folds

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True vocal cords– Formed by upper free border of cricovocal lig– Rima glottidis (glottis)

• Gap b/t true vocal cords• Parts :

– Intermembranous : ant 60%, bounded each side with vocal fold

– Intercartilaginous : Post 40%, bounded each side with vocal pr and base of arytenoid cart

Ventricle (laryngeal sinus)– Space b/t False and true VC with deep horizontal

groove in lateral wall– Opening at ant end : Saccule of larynx– Covered with mucous membrane– Extend up for few mm b/t thyroid lamina and

vestibular fold

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HISTOLOGY OF LARYNX

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SHAPE OF RIMA GLOTTIDIS DURING DIFFERENT MOVEMENTS OF VOCAL CORDS

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NERVE SUPPLY

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ILN : only sensory

ELN : only motor

RLN : sensory and motor

ARTERIAL SUPPLY

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Sup Laryngeal Artery

Inferior Laryngeal Artery

VENOUS DRAINAGE

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Sup Thyroid Vein

Inf Thyroid Vein

LYMPHATIC DRAINAGE

• Above VC upper deep cervical {anterosuperior group}

• Below VC lower deep cervical {posteroinferior group}

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CruxAbove VC Below VC

Arterial supply Sup laryngeal art Inf laryngeal art

Venous drainage Sup thyroid Vein Inf thyroid Vein

Lymph drainage Upper Deep cervical LN

Lower deep cervical LN

Nerve supply Sensory: ILN Sensory: RLN02--04--2011 50

MECHANISM OF PHONATION

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APPLIED ANATOMY

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Requires laryngeal mirror and head mirror

Structures seen……………

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LARYNGOSCOPY- Indirect laryngoscopy

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Direct laryngoscopyDone under GA“Sniff position”Macintosh LaryngoscopeBefore orotracheal/ endotracheal intubation

Cricothyrotomy

• Emergency airway establishment

• Cricothyroid ligament opened

• Transverse incision,pocketknife

• Converted to standard tracheotomy soon to prevent laryngeal stenosis

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Consequences of thyroidectomy on larynx

HEIMLICH MANEUVER

• Foreign body in laryngeal cavity• Choking,asphyxia

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MALFORMATIONS OF LARYNX• Laryngomalacia:

– Supraglottic structures(epiglottis,arytenoid cartilages) abnormally soft & pliable Collapse inwards during inspiration

– S/S: feeding difficulty,stridor from birth,louder in supine position

– Diagnosis: laryngoscopy-”Omega shaped” epiglottis

– Treatment: • Resolve by 2 yrs• Temporary tracheostomy

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• Others

– Congenital laryngeal cyst

– Congenital laryngocele

– Congenital Subglottic stenosis

– Congenital vocal cord paralysis

– Subglottic hemangioma

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SINGERS /SCREAMERS/CLERGYMENS NODULES

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LARYNGOCELE

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Internal

External

Increased air pressure in laryngeal sinusTrumpet players,glass blowers,weight liftersSaccule dilates to produce air filled cystic swelling

NEUROGENIC DISORDERS OF LARYNXRecurrent laryngeal nerve paralysis

Unilateral :

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Bilateral

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Superior laryngeal nerve paralysis

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SIMON’S LAW

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Infectious & inflammatory diseases of larynx

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Reinke’s edema

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TUMOURS OF LARYNX

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Thank you