Anatomy and Physiology of the Larynx Copy 2

7/30/2019 Anatomy and Physiology of the Larynx Copy 2

1/61


2/61

Objectives To discuss the basic anatomy of the larynx

To enumerate the main functions of the larynx


3/61


4/61

Laryngeal Cartilages Paired

Arytenoid cartilage

Corniculate cartilage Cuneiform cartilage

Unpaired:

Thyroid cartilage

Cricoid cartilage Epiglottis


5/61

Thyroid Cartilage Hyaline cartilage

Largest Encloses the larynx

anteriorly and laterally

Two alae

Ossification


6/61

Cricoid Cartilage Hyaline cartilage

Directly below thethyroid cartilage

Stongest Shape: Signet ring

Lamina flat portion

Only complete annularsupport of the larynx

Articulates w/ Inferiorcornu of the thyroidcartilage


7/61

Epiglottis Fibroelastic cartilage

Leaf-shaped structure

Petiole small narrowportion of the glottis


8/61

Arytenoid Cartilage Mostly hyaline cartilage

Smaller in size

Responsible for opening and closing of the larynx Shape: pyramidal


9/61

Arytenoid CartilageAnterior

Vocal process -receives theattachement of themobile end of each

VC

Lateral

Muscular process

Articulation

Cricoarytenoid joint


10/61

Corniculate Cartilages Fibroelastic

Cartilages of Santorini

Small cartilages above the arytenoid and in thearyepiglottic folds


11/61

Cuneiform Cartilages Firboelastic cartilages

Cartilages of Wrisberg

Elongated pieces ofsmall yellow elasticcartilage in thearyepiglottic folds


12/61

Triticeous Cartilage

Cartilago triticea

Small elastic cartilagein the lateralthyrohyoid ligament


13/61

Laryngeal Ligaments

Extrinsic

Thyrohyoid membraneand ligaments

Cricothyroid membraneand ligaments

Cricotracheal ligament

Epiglottis

Intrinsic

Elastic membrane

Quadrangular

membrane Conus elasticus

(cricovocal membrane)

Median cricothyroid

ligamentVocal Ligament

Thyroepiglotticligament


14/61

Extrinsic Ligaments

Thyrohyoid membrane pierced on each side by:

1. Superior laryngeal vessels2. Internal branch of superiorlaryngeal nerve

Median thyrohyoid ligament

thickened median portion

Lateral thyrohyoid ligament

thickened posterior border

- where cartilago triticea isoften found


15/61

Extrinsic Ligaments Cricothyroid

membrane and

ligaments May be pierced

for emergencytracheotomy

(cricothyrotomy)


16/61

Extrinsic Ligaments Cricotracheal Ligament

Attaches the cricoid cartilage to the first attached ring

Epiglottis

suspended in position by membranous connections tothe hyoid bone, thyroid cartilage and base of the tongue


17/61


18/61

Intrinsic Ligaments Elastic membrane

Divided into upper and lower parts by the ventricle ofthe larynx

Quadrangular membrane

Upper part of the elastic membrane

Boundaries

Epiglottis , arytenoid, corniculate cartilage, false cord Forms part of wall between upper pyriform sinus and

laryngeal vestibule


19/61

Intrinsic Ligaments

Conus elasticus (cricovocal membrane)

Lower part of elastic membrane

Composed mainly of yellow elastic tissue

Boundaries Inferior: superior border of cricoid cartilage

Superoanterior: deep surface of angle thyroid cartilage

Superoposterior: vocal process of arytenoid cartilage

Median cricothyroid ligament thickened anteior part

Vocal Ligament free upper edge

Thyroepiglottic ligament


20/61


21/61

Cavity of the Larynx Divided into 3 parts:

Vestibule

Ventricle

Subglottic space


22/61

Cavity of the LarynxVestibule boundaries:

Anterior: posterior surface of epiglottis

Posterior: interval between arytenoidcartilages

Lateral: inner surface of aryepiglottic foldsand upper surfaces of the false cord


23/61

Cavity of the Larynx

Glottis (rima glottidis) Abduction: Respiration,

wide and triangular Adduction: Phonation,

slit-like appearance

Ventricle Saccule conical pouch at anterior part


24/61


Subglottic space

Preepiglottic space

Boundaries:

Anterior: thyrohyoid membrane

Anteroasuperior: hyoid Superior: vallecula

Posterior: part of the epiglottis

Lateral: hyoepiglottic ligament


25/61


False Cords (ventricular bands) Anteriorly: angle of the thyroid

cartilage Posteriorly: bodies of the

arytenoid cartilage

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


26/61

Laryngeal Joints Cricothyroid Joint

Between inferior cornuof the thyroid cartilage

and facet on the cricoidcartilage at the junctionof the arch and lamina

Two movements:

Rotation

Gliding

Cricoarytenoid Joint

bet. base of thearytenoid cartilage and

the facet on the upperborder of the lamina ofthe cricoid cartilage

Two movements:

Rotation

Gliding


27/61

Intrinsic Muscles

Interarytenoid muscle Transvers

Oblique

Post. Cricoarytenoid m.

Lateral cricoarytenoidm.

Thyroarytenoid m.

Cricothyroid m.

Laryngeal Muscles Extrinsic Muscles

Depressor group

Elevator group Constrictor muscles

Pharyngeal muscles

Depressor Origin Insertion Action


28/61

Depressormuscles

Origin Insertion Action

Sternohyoid (C2,C3)

manubrium of

sternum and

medial end of

clavicle

oblique line of the

thyroid cartilage

depresses/stabilizes

the hyoid bone

Thyrohyoid (C1) oblique line of thethyroid cartilage

lower border of thehyoid bone

elevates the larynx;depresses/stabilizes

the hyoid bone

Omohyoid (C2,C3)

superior borderof scapula nearthesuprascapularnotch

inferior border ofhyoid bone

depresses, retractsand steadies thehyoid duringswallowing andspeaking

Elevator Origin Insertion Action


29/61

Elevatormuscles


Geniohyoid(C1)

inferior mentalspine of mandible

body of hyoidbone

pulls the hyoid boneanterosuperiorly, and shortens

the floor of the mouth andwidens the pharynx

Digastrics(Ant. CN V;

Post. N. VII)

anterior belly-digastric fossa ofmandible,posterior belly-mastoid notch oftemporal bone

intermediatetendon to bodyand greater hornof hyoid bone

depresses the mandible andraises the hyoid bone. Also, itsteadies the hyoid bone duringswallowing and speaking

Mylohyoid(V)

mylohyoid line ofmandible

raphe and bodyof hyoid bone

elevates the hyoid bone, floor ofthe mouth and the tongueduring swallowing and speaking

Stylohyoid

(VII)

styloid process ofthe temporal

bone

body of hyoidbone

elevates and retracts the hyoidbone, thereby elongating the

floor of the mouth


30/61

Elevator Origin Insertion Action


31/61

Elevatormuscles


Stylopharyngeus

(CN IX)

styloidprocess oftemporalbone

posterior andsuperior borders ofthyroid cartilage withpalatopharyngeusmuscle

elevates the pharynx andlarynx and expands thesides of the pharynx

Salpingopharyngeus(pharyngeal plexus) cartilaginouspart of theauditory tube

blends withpalatopharyngeusmuscle

elevates the pharynx andlarynx and opens theorifice of the auditory tubeduring swallowing

Palatopharyngeus hard palateand palatineaponeurosis

lateral wall ofpharynx

tenses the soft palate andpulls the walls of thepharynx superiorly,anteriorly and mediallyduring swallowing


32/61


33/61


34/61


35/61

Muscles Controlling Movements of the Vocal Cords

Intrinsic

Muscles


Cricothyroid(ELN)

arch of the cricoid

cartilage

inferior border of the

thyroid cartilage

draws the thyroid

cartilage forward,

lengthening the vocal

ligaments, tenses

vocal cords

Thyroarytenoid(vocalis, ILN)

inner surface of the

thyroid cartilage

lateral border of the

arytenoid cartilage

relaxes and adducts

the vocal folds

Lateralcricoarytenoid(ILN)

arch of the cricoid

cartilage

muscular process of

the arytenoid cartilage

Adducts the vocal

cords by rotating the

arytenoid cartilage


36/61


37/61

Muscles Controlling Movements of the

Vocal CordsIntrinsicMuscles


Posteriorcricoarytenoid(ILN)

posterior surface ofthe lamina of the

cricoid cartilage

muscular process ofthe arytenoid cartilage

Adducts the vocalcords by rotating the

arytenoid cartilage

Interarytenoid m.,transverse (ILN)

posterior surface ofthe arytenoid

cartilage

posterior surface ofthe contralateral

arytenoid cartilage

Closes posterior partof rima glottidis by

approximating

arytenoid cartilages


38/61


39/61


40/61

Mucous Membrane Stratified squamous epith.: over vocal cords and upper

part of vestibule of larynx

Ciliated columnar epith.: remainder of the cavity

Mucous glands:

Ventricles and sacculi

Posterior surface of epiglottis

Margins of aryepiglottic folds Reinkes layer of connective tissue: No glands and no

lymph vessels


41/61


42/61


43/61

Blood Supply Upper Larynx

External carotid artery

Superior thyroid artery

Superior laryngealartery

Lower Larynx

Subclavian artery Thyrocervical artery

Inferior thyroid artery

Inferior laryngeal artery


44/61

Venouos Drainage Upper Larynx

Superior laryngeal vein

Superior thyroid vein

Internal jugular vein

Lower Larynx

Inferior laryngeal vein

Inferior thyroid vein Innominate vein


45/61

Lymphatic Drainage Main: Deep Cervical group L.N.

Supraglottic area98%: Pedicle Ant. End of aryepiglottic fold -> passlaterally and leave the larynx through the thyrohyoidmembrane ->Upper deep cervical nodes (bet. Digastric

tendon and omohyoid muscle)2%: Lower cervical chain or spinal accessory chain


46/61

Lymphatic Drainage Infraglottic area 3 pedicles

1. Anterior pedicle -> cricothyroid membrane ->prelaryngeal (Delphian) nodes ->deep inferior cervicalnodes

2. 2 Posterolateral pedicles -> cricotrachealmembrane -> paratracheal chain/others to inferior

jugular chain


47/61


48/61


49/61

Basic Functions

Protection

Respiration

Phonation Fixation of chest

Closure of glottis


50/61

ProtectionActs as a sphincter

Closure of the laryngealinlet

Closure of the glottis

Cessation of respiration

Cough relfex, expulsionof secretions andforeign bodies


51/61

Protection 3 Sphincteric tiers of airway protection:

Contraction of superior division of the thyroarytenoid

muscles Contraction of middle thyroarytenoid fibers

Contraction of inferior division of thyroarytenoid


52/61


53/61

PhonationVoice produced by

vibration of the vocalcords

Fundamental toneproduced at the larynx

Modified by resonatingchambers of the upperaerodigestive tract


54/61

Phonation Cricothyroid muscles

Position the vocal cordsnear the midline

Lengthens true cords aspitch increases

Thyroarytenoid muscles

Provide finer isometricmodifications

Increases internaltension of true cord,producing cordthinning


55/61

Afferent System Greatest in the laryngeal inlet, especially the laryngeal

surface of the epiglottis

serves as a protective function of the lower respiratorytract


56/61

Efferent System

Superior Laryngeal n. Innervates cricothyroid

Recurrent Laryngeal n. Innervates all muscles EXCEPT cricothyroid

Bilateral innervation to interarytenoid muscles Posterior Cricoarytenoid

Innervated by inferior laryngeal nerve

Sole abductor

Thyroarytenoid and Lateral cricoarytenoid Major adductors

Interarytenoid muscles Close the posterior gap in the glottis


57/61

Laryngeal Voice Production Myoelastic-Aerodynamic Theory

Laryngeal muscles position VC ->Muscular and passiveforces of exhalation-> Increase subglottic pressure->

Exceeds muscular opposition -> Glottic chink forcedopen -> Release of air -> Decreased subglottic pressure -> VC approximation

Myoelastic forces of vocal cords exceed the aerodynamic

forces, enhanced by Bernouillis effect Resulting waveform: sawtooth type; relaxation oscillator


58/61


59/61

Laryngeal Voice Production Neuromuscular or Neurochronaxic Theory

Suggested that each new vibratory cycle is initiated bycentral neuronal impulses via the vagus nerve to the

appropriate laryngeal muscles Rate of impulses delivered to larynx = frequency of vocal

cord vibration

Disproved by physiologic and audiometric analysis


60/61

Components of Vocal MechanismActivator

Energy produced by expiratory phase of breathingapparatus

Generator

Glottis vibrates at different frequencies

Resonator

Sound modulation occurring in resonating chambersArticulators

Precise movements of palate, tongue, teeth, and lips


61/61

Thank You

Documents

Anatomy and Physiology of the Larynx Copy 2