The Anatomy and Physiology of the Larynx

Anatomy and Physiology of the Larynx 7/15/2012 www.nayyarENT.com Dr. Supreet Singh Nayyar, AFMC For more presentations, please visit www.nayyarENT.com 1

Objectives To discuss the basic anatomy of the larynx To enumerate the main functions of the larynx 7/15/2012 www.nayyarENT.com 2

Laryngeal Cartilages Paired Arytenoid cartilage Corniculate cartilage Cuneiform cartilage Unpaired: Thyroid cartilage Cricoid cartilage Epiglottis 7/15/2012 www.nayyarENT.com 4

Thyroid Cartilage 7/15/2012 Hyaline cartilage Largest Encloses the larynx anteriorly and laterally Two alae Ossification www.nayyarENT.com 5

Cricoid Cartilage Hyaline cartilage Directly below the thyroid cartilage Strongest Shape: Signet ring Lamina flat portion Only complete annular support of the larynx Articulates w/ Inferior cornu of the thyroid cartilage 7/15/2012 www.nayyarENT.com 6

Epiglottis Fibroelastic cartilage Leaf-shaped structure Petiole small narrow portion of the glottis 7/15/2012 www.nayyarENT.com 7

Arytenoid Cartilage Mostly hyaline cartilage Smaller in size Responsible for opening and closing of the larynx Shape: pyramidal 7/15/2012 www.nayyarENT.com 8

Arytenoid Cartilage Anterior Vocal process - receives the attachement of the mobile end of each VC Lateral Muscular process Articulation Cricoarytenoid joint 7/15/2012 www.nayyarENT.com 9

Corniculate Cartilages Fibroelastic Cartilages of Santorini Small cartilages above the arytenoid and in the aryepiglottic folds 7/15/2012 www.nayyarENT.com 10

Cuneiform Cartilages Firboelastic cartilages Cartilages of Wrisberg Elongated pieces of small yellow elastic cartilage in the aryepiglottic folds 7/15/2012 www.nayyarENT.com 11

Triticeous Cartilage 7/15/2012 Cartilago triticea Small elastic cartilage in the lateral thyrohyoid ligament www.nayyarENT.com 12

Laryngeal Ligaments Intrinsic Elastic membrane Quadrangular membrane Conus elasticus (cricovocal membrane) Median cricothyroid ligament Vocal Ligament Thyroepiglottic ligament Extrinsic Thyrohyoid membrane and ligaments Cricothyroid membrane and ligaments Cricotracheal ligament Epiglottis 7/15/2012 www.nayyarENT.com 13

Extrinsic Ligaments Thyrohyoid membrane pierced on each side by: 1. Superior laryngeal vessels 2. Internal branch of superior laryngeal nerve Median thyrohyoid ligament thickened median portion Lateral thyrohyoid ligament thickened posterior border - where cartilago triticea is often 7/15/2012 www.nayyarENT.com 14 found

Extrinsic Ligaments Cricothyroid membrane and ligaments May be pierced for emergency tracheotomy (cricothyrotomy) 7/15/2012 www.nayyarENT.com 15

Extrinsic Ligaments Cricotracheal Ligament Attaches the cricoid cartilage to the first attached ring 7/15/2012 Epiglottis suspended in position by membranous connections to the hyoid bone, thyroid cartilage and base of the tongue www.nayyarENT.com 16

Intrinsic Ligaments Elastic membrane Divided into upper and lower parts by the ventricle of the 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 7/15/2012 www.nayyarENT.com 17

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 7/15/2012 www.nayyarENT.com 18

Cavity of the Larynx 7/15/2012 Divided into 3 parts: Vestibule Ventricle Subglottic space www.nayyarENT.com 19

Cavity of the Larynx 7/15/2012 Vestibule boundaries: Anterior: posterior surface of epiglottis Posterior: interval between arytenoid cartilages Lateral: inner surface of aryepiglottic folds and upper surfaces of the false cord www.nayyarENT.com 20

Cavity of the Larynx Ventricle Saccule conical pouch at anterior part 7/15/2012 www.nayyarENT.com Glottis (rima glottidis) Abduction: Respiration, wide and triangular Adduction: Phonation, slit- like appearance 21

Cavity of the Larynx 7/15/2012 Subglottic space Preepiglottic space Boundaries: Anterior: thyrohyoid membrane Anteroasuperior: hyoid Superior: vallecula Posterior: part of the epiglottis Lateral: hyoepiglottic ligament www.nayyarENT.com 22

Cavity of the Larynx False Cords (ventricular bands) Anteriorly: angle of the thyroid cartilage Posteriorly: bodies of the arytenoid cartilage 7/15/2012 www.nayyarENT.com 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 23

Laryngeal Joints Cricothyroid Joint Between inferior cornu of the thyroid cartilage and facet on the cricoid cartilage at the junction of the arch and lamina Two movements: Rotation Gliding Cricoarytenoid Joint bet. base of the arytenoid cartilage and the facet on the upper border of the lamina of the cricoid cartilage Two movements: Rotation Gliding 7/15/2012 www.nayyarENT.com 24

Laryngeal Muscles Intrinsic Muscles Interarytenoid muscle Transvers Oblique Post. Cricoarytenoid m. Lateral cricoarytenoid m. Thyroarytenoid m. Cricothyroid m. Extrinsic Muscles Depressor group Elevator group Constrictor muscles Pharyngeal muscles 7/15/2012 www.nayyarENT.com 25

Depressor muscles 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 7/15/2012 oblique line of the thyroid cartilage lower border of the hyoid bone elevates the larynx; depresses/stabilizes the hyoid bone www.nayyarENT.com Thyrohyoid (C1) superior border of scapula near the suprascapular notch inferior border of hyoid bone depresses, retracts and steadies the hyoid during swallowing and speaking Omohyoid (C2, C3) 26

Elevator muscles Origin Insertion Action inferior mental spine of mandible body of hyoid bone pulls the hyoid bone anterosuperiorly, and shortens the floor of the mouth and widens the pharynx Geniohyoid (C1) 7/15/2012 anterior belly- digastric fossa of mandible, posterior belly- mastoid notch of temporal bone intermediate tendon to body and greater horn of hyoid bone depresses the mandible and raises the hyoid bone. Also, it steadies the hyoid bone during swallowing and speaking Digastrics (Ant. CN V; Post. N. VII) www.nayyarENT.com mylohyoid line of mandible raphe and body of hyoid bone elevates the hyoid bone, floor of the mouth and the tongue during swallowing and speaking Mylohyoid (V) 27 styloid process of the temporal bone body of hyoid bone elevates and retracts the hyoid bone, thereby elongating the floor of the mouth Stylohyoid (VII)

Elevator muscles Origin Insertion Action styloid process of temporal bone posterior and superior borders of thyroid cartilage with palatopharyngeus muscle elevates the pharynx and larynx and expands the sides of the pharynx Stylopharyngeus (CN IX) 7/15/2012 cartilaginous part of the auditory tube blends with palatopharyngeus muscle elevates the pharynx and larynx and opens the orifice of the auditory tube during swallowing Salpingopharyngeus (pharyngeal plexus) www.nayyarENT.com hard palate and palatine aponeurosis lateral wall of pharynx tenses the soft palate and pulls the walls of the pharynx superiorly, anteriorly and medially during swallowing Palatopharyngeus 29

Muscles Controlling the Laryngeal Inlet 7/15/2012 Intrinsic Muscles Origin Insertion Action www.nayyarENT.com muscular process of the arytenoid cartilage posterior surface of the contralateral arytenoid cartilage, near its apex draws arytenoid cartilages together, adducting the vocal folds (closure of glottis) Interarytenoid m., oblique (RLN) inner surface of the thyroid cartilage near the laryngeal prominence lateral surface of the epiglottic cartilage draws the epiglottic cartilage downward Thyroepiglottic (ELN) 30

Muscles Controlling Movements of the Vocal Cords Intrinsic Muscles Origin Insertion Action 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 7/15/2012 www.nayyarENT.com Thyroarytenoid (vocalis, ILN) inner surface of the thyroid cartilage lateral border of the arytenoid cartilage relaxes and adducts the vocal folds Lateral cricoarytenoid (ILN) arch of the cricoid cartilage muscular process of the arytenoid cartilage Adducts the vocal cords by rotating the arytenoid cartilage 31

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Muscles Controlling Movements of the Vocal Cords Intrinsic Muscles Origin Insertion Action 7/15/2012 www.nayyarENT.com Posterior cricoarytenoid (ILN) posterior surface of the lamina of the cricoid cartilage muscular process of the arytenoid cartilage Abducts the vocal cords by rotating the arytenoid cartilage Interarytenoid m., transverse (ILN) posterior surface of the arytenoid cartilage posterior surface of the contralateral arytenoid cartilage Closes posterior part of rima glottidis by approximating arytenoid cartilages 33

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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 Reinke s layer of connective tissue: No glands and no lymph vessels 7/15/2012 www.nayyarENT.com 35

Vocal Folds 7/15/2012 www.nayyarENT.com 36

Nerve Supply Supplied by Vagus nerve: Superior laryngeal n. Internal branch (sensory) areas above the glottis External branch (motor and sensory) Motor Cricothyroid muscle Sensory Anterior infraglottic larynx at level of cricothyroid membrane Inferior (recurrent) laryngeal n. Motor all intrinsic laryngeal muscles of SAME side (except cricothyroid) and interarytenoid muscle of BOTH sides Sensory areas below the glottis 7/15/2012 www.nayyarENT.com 37

Blood Supply Upper Larynx External carotid artery Superior thyroid artery Superior laryngeal artery Lower Larynx Subclavian artery Thyrocervical artery Inferior thyroid artery Inferior laryngeal artery 7/15/2012 www.nayyarENT.com 38

Venouos Drainage Upper Larynx Superior laryngeal vein Superior thyroid vein Internal jugular vein Lower Larynx Inferior laryngeal vein Inferior thyroid vein Innominate vein 7/15/2012 www.nayyarENT.com 39

Lymphatic Drainage Main: Deep Cervical group L.N. 7/15/2012 Supraglottic area 98%: Pedicle Ant. End of aryepiglottic fold -> pass laterally and leave the larynx through the thyrohyoid membrane ->Upper deep cervical nodes (bet. Digastric tendon and omohyoid muscle) 2%: Lower cervical chain or spinal accessory chain www.nayyarENT.com 40

Lymphatic Drainage Infraglottic area 3 pedicles 1. Anterior pedicle -> cricothyroid membrane -> prelaryngeal (Delphian) nodes ->deep inferior cervical nodes 2. 2 Posterolateral pedicles -> cricotracheal membrane -> paratracheal chain/others to inferior jugular chain 7/15/2012 www.nayyarENT.com 41

PHYSIOLOGY 7/15/2012 www.nayyarENT.com For more presentations in ENT, visit www.nayyarENT.com 42

Basic Functions Protection Respiration Phonation Fixation of chest Closure of glottis 7/15/2012 www.nayyarENT.com 43

Protection Acts as a sphincter Closure of the laryngeal inlet Closure of the glottis Cessation of respiration Cough relfex, expulsion of secretions and foreign bodies 7/15/2012 www.nayyarENT.com 44

Protection 7/15/2012 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 www.nayyarENT.com 45

Respiration Assists in regulation of gaseous exchange with the lung and maintenance in acid-base balance Glottis opens a fraction of a second before air is drawn in by descent of the diaphragm 7/15/2012 www.nayyarENT.com Posterior cricoarytenoids Phasic inspiratory abduction Synchronous w/respiration Cricothyroid muscle Phasic inspiratory contraction/adduction Increases AP diameter of glottic chink 46

Phonation in brief Voice produced by vibration of the vocal cords Fundamental tone produced at the larynx Modified by resonating chambers of the upper aerodigestive tract 7/15/2012 www.nayyarENT.com 47

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