3Objectives Describe anatomical structure of larynx. Enlist the cartilages of the larynx.Define inlet of the larynx.Enlist the extrinsic and intrinsic muscles of the larynx with their nerve supply and actions.
6larynx- The larynx is the organ of phonation (voice production) in addition to its respiratory function (air way). It is formed of a group of cartilages connected by Muscles, Ligaments and joints. Site: It lies below the hyoid bone in the midline of the neck at the level of C vertebrae.Lateral viewAnterior view
7Structure A cartilaginous skeleton Membranes and ligaments The larynx consists of four basic components:A cartilaginous skeletonMembranes and ligamentsIntrinsic and extrinsic musclesMucosal lining
8Cartilages of the Larynx Single cartilagesPaired cartilages- Thyroid cartilage.- Arytenoid cartilage.- Cricoid cartilage.- Corniculate cartilage.- Epiglottic cartilage.- Cuneiform cartilage.All the cartilages, except the epiglottis, are of hyaline type.Epiglottis is formed of elastic cartilageThe cartilages are:Connected by joints, membranes & ligamentsMoved by muscles
91. Thyroid cartilageIt consists of two laminae which are fused anteriorly to form the laryngeal prominence (Adam’s apple) but they are separated posteriorly. - Superiorly the area between the two laminae is called the superior thyroid notch.
102. Cricoid cartilageIt is signet-ring in shape (it is the only complete cartilaginous ring in the upper respiratory airway).- It lies at the level of C. 6.
123. Epiglottis- It is leaf-shaped elastic cartilage which lies behind the tongue.- It has superior rounded free border and an inferior tapering end which is attached to the upper part of the thyroid notch.
134.Arytenoid cartilage It is pyramidal in shape. - The base articulates with the upper facet of the quadrate lamina of the cricoid cartilage.
145. Corniculate cartilage - It is a small cartilaginous nodule.- It articulates with the apex of each arytenoid and lies in the aryepiglottic fold.6. Cuneiform cartilage- It is another small cartilaginous nodule which articulates with the upper surface of the corniculatecartilage and lies in the aryepiglottic fold
15Ligaments and Membranes 1. Thyrohyoid membrane:- It connects the upper border of the thyroid lamina to the body and the greater horns of the hyoid bone.
162. Hyoepiglottic ligament - It is a small elastic ligament which connects the lower part of the anterior surface of the epiglottis to the hyoid bone.3. Thyroepiglottic ligament- It is a small elastic ligament which connects the tapering lower end of the epiglottis to the innersurface of the thyroid cartilage.
17Quadrangular membrane: Extends between the epiglottis and the arytenoid cartilagesIts lower free margin forms the vestibular ligament that lies within the vestibular foldCricothyroid membrane (conus elasticus):Lower margin is attached to upper border of cricoid cartilageUpper free margin forms vocal ligament
21Laryngeal CavityRima vestibuliExtends from laryngeal inlet to lower border of the cricoid cartilageNarrow in the region of the vestibular folds (rima vestibuli)Narrowest in the region of the vocal folds (rima glottidis)Divided into three parts:Supraglottic part, the part above the vestibular folds, is called the vestibuleThe part between the vestibular & the vocal folds, is called the ventricleInfraglottic part, the part below the vocal foldsRima glottidisABC
22Mucous MembraneThe cavity is lined with ciliated columnar epitheliumThe surface of vocal folds, because of exposure to continuous trauma during phonation, is covered with stratified squamous epitheliumContains many mucous glands, more numerous in the saccule (for lubrication of vocal folds)MusclesDivided into two groups:Extrinsic muscles: divided into two groupsElevators of the larynxDepressors of the larynxIntrinsic muscles: divided into two groupsMuscles controlling the laryngeal inletMuscles controlling the movements of the vocal cords
23Elevators of the Larynx The Suprahyoid MusclesDigastricStylohyoidMylohyoidGeniohyoidThe Longitudinal Muscles of the PharynxStylopharyngeusSalpingopharyngeusPalatopharyngeusDepressors of the LarynxThe Infrahyoid MusclesSternohyoidSternothyroidOmohyoid
24Muscles of the Larynx I. Muscles acting on the laryngeal inlet = Muscles closing the laryngeal inlet:1. Aryepiglottic muscles :Action: Closure of the laryngeal inlet.2. Transverse arytenoid :Actions: (narrowing the laryngeal inlet) and adducts the vocal cords.
253. Oblique arytenoids : Actions: They narrow the laryngeal inlet) and adducts the vocal cords.
26II. Muscles acting on the vocal cords A: Muscles producing abduction of the vocal cords:* Posterior crico-arytenoid:- It is the ONLY abductor to the vocal cordsOrigin: Posterior surface of the lamina of the cricoid cartilage.Insertion: Muscular process of the arytenoid.Actions:- Abduction of the vocal cords.
27B. Muscles producing adduction of the vocal cords 1. Lateral crico-arytenoid : Action: It draws the muscular process forwards so it rotates the vocal process inwards and adducts (closes) the vocal cords. 2. Transverse arytenoid 3. Oblique arytenoid
28C. Muscles stretching (tensing) the vocal cords 1. Cricothyroid muscle - It lies on the outer surface of the larynx. Origin: Lateral aspect of the cricoid arch. Insertion: Into the inferior horn and lower border of the thyroid lamina. Actions: It draws the thyroid cartilage downwards and forwards, so it lengthens and tenses the vocal cords (responsible for the sharp loud voice).
29D. Muscles relaxing the vocal cords 1. Thyroarytenoid muscle Actions: It shortens and relaxes the vocal cords, so it changes the pitch of the voice. 2. Vocalis muscle (it is the lower fibers of the thyro-arytenoid muscle) Action: Relaxation of the vocal cords.
30Movements of the Vocal Cords AdductorsLateral cricoarytenoidTransverse arytenoidAbductorPosterior cricoarytenoidMovements of the Vocal CordsAdductionAbduction
31Nerve supply A. Motor supply - All intrinsic muscles of the larynx are supplied by the “recurrent laryngeal nerve”EXCEPT cricothyroid which is supplied by the external laryngeal nerve.B. Sensory supply- Above the vocal cords Internal laryngeal nerve (from vagus N).- Below the vocal cords Recurrent laryngeal nerve (from vagus N).
32Blood supply Blood supply: A. Arterial supply: 1. Above the vocal cords: Superior laryngeal artery (from the superior thyroid artery).2. Below the vocal cords: Inferior laryngeal artery (from the inferior thyroid artery).B. Venous drainage:- It drains its venous blood into the corresponding superior and inferior thyroid veinsrespectively.