Anatomy Of Phonation PDF

Phonation Dr. Ruba Almelaifi.  Laryngeal membranes Extrinsic ligaments Intrinsic ligaments  Laryngeal membranes Extrinsic ligaments Provide attachment between the hyoid or trachea and the cartilages of the larynx Thyrohyoid membrane: Connect the larynx...

Phonation Dr. Ruba Almelaifi.  Laryngeal membranes Extrinsic ligaments Intrinsic ligaments  Laryngeal membranes Extrinsic ligaments Provide attachment between the hyoid or trachea and the cartilages of the larynx Thyrohyoid membrane: Connect the larynx to the hyoid bone – Lateral thyrohyoid ligament – Median thyrohyoid ligament  Laryngeal membranes Extrinsic ligaments Cricotracheal ligament (attaches the trachea to the cricoid cartilage) Hyoepiglottic Lateral and median glossoepiglottic ligaments  Laryngeal membranes Intrinsic membranes and ligaments Connect the cartilages of the larynx and form supportive structure for the laryngeal cavity Forms the cavities of the larynx Fibroelastic membranes: – Upper quadrangular membrane – Aryepiglottic folds (by which epiglottis is attached to arytenoids)  Laryngeal membranes Intrinsic ligaments – Lateral thickening of the cricothyroid membrane  Lower cornus elasticus Lines the inside portion of the cricoid cartilage and up under the vocal folds It directs the air that comes out of lungs (like a funnel) and push it to the vocal ligaments where we want vibration to occur  Cricothyroid membrane (or ligament) – Attached to the thyroid cartilage – Attaches to the vocal process of the arytenoid cartilage – Vocal ligaments: thickening of the upward (upper) free extension (margin) of the cornus elasticus  Quadrangular membrane Attaches to the lateral surface of the epiglottis, arytenoid cartilage, corniculate cartilage and to the thyroid cartilage just above the point where vocal ligament attaches. It has free lower margin which is thickined  forming the false vocal folds (vestibular ligament)  The vestibular ligaments is located above and to the side of the vocal folds The mucosa folds around the ligaments (vestibular and the vocal) to form the vocal folds (vocal folds and vestibular folds)  Aryepiglottic folds From side of epiglottis to the arytenoid apex Form upper margin of quadrangular membrane and laterally the aryepiglottic folds.  The Vocal Folds Bands of mucous membrane, connective tissue and thyrovocalis muscle – They maybe moved in or out of the airstream – Their attachment to the arytenoids allow adduction and abduction movement of the vocal folds which control the degree of airflow between the folds Fine structure of the Vocal folds  Fine structure of the Vocal folds Composed of five layers of tissues: 1st layer  Superficial layer – Protective epithelial layer and an underlying layer of basement membrane (give the folds the white appearance seen during laryngoscope) – Help to keep the vocal folds moist  Fine structure of the Vocal folds 2nd layer  Superfecial layer of lamina propria (SLP) – Elastic fibers (can be extensively stretched and provide cushion for the vocal folds), provides least resistance to vibration – This layer is important to the proper function of the vocal folds  Fine structure of the Vocal folds 3rd layer  intermediate layer of lamina propria (ILP), – High concentration of collagen and elastic fibers (with SLP this layer provide elasticity and strength to the vocal folds constitute the vocal ligament) – Thickened at the anterior and posterior ends of the vocal folds to provide protection of the vocal folds from mechanical damage.  Fine structure of the Vocal folds 4th layer  Deep layer of lamina propria (DLP), – Made up of collagen, prohibit extension – ILP and DLP combine to constitute the vocal ligament  Fine structure of the Vocal folds 5th layer Vocalis muscle – thyroarytenoid muscle (thyrovocalis, thyromuscularis) – This constitute the bulk of the vocal folds There are both passive (SLP, ILP and DLP) and active elements (thyroarytenoid muscle)  Cavities of the larynx The aditus laryngis: – The entry to the larynx from the pharynx above – It is the entry way to the first cavity (vestibule) – The anterior boundary of the aditus is the epiglottis – Its lateral margins are aryepiglottic fold  Pumps under the aryepiglottic fold: – Cuneiform cartilage embedded within the fold – The other more posterior pump is by the corniculate cartilage on the arytenoids  Cavities of the larynx Vestibule: – The 1st cavity: between the aditus and the (ventricular) vestibular folds – Ventricular folds are also known as the false vocal folds because they are not used for phonation except in rare (and clinically significant) cases  Cavities of the larynx – Lateral walls of the vestibule aryepiglottic fold – Posterior wall  membrane that covers the arytenoid cartilages – False vocal folds are made up of mucous membrane and fibrous vestibular ligament (no muscle tissue)  Cavities of the larynx The 2nd cavity: laryngeal ventricle – Between the false and the true vocal folds The 3rd cavity: the glottis, the space between the vocal folds – The most important laryngeal space for speech – Defined by variable sphincters that permit voicing – The glottis area is variable according to the moment to moment configuration of the vocal folds – Posterior gap (opening between the vocal folds) is about 8mm at rest  The lateral margin of the glottis are the vocal folds and the arytenoids  Cavities of the larynx The 4th cavity - Conus elasticus: – begins at the margins of the true vocal folds and extend to the inferior border of the cricoid cartilage widening from the vocal folds to the base of the cricoid cartilage Cavities of the larynx  Movement of the Cartilages Cricothyroid and cricoarytenoid joints are the only movable parts of the larynx Cricothyroid joint permit the cricoid and thyroid to rotate and glide relative to each other – thyroid cartilage to rock down (from the front) – thyroid cartilage glide backward and forward slightly – Provides major adjustment for change in vocal pitch Cricothyroid Joint  Cricoarytenoid Joint between cricoid convex upper surface and arytenoid concave base surface Synovial joint permit gliding, rocking, and minimal rotation – Rocking action (medially and laterally)  bring the vocal processes towards each other Vocal folds approximate each other (adduction) – Gliding movement along the axis Facilitate change in vocal fold length Cricoarytenoid Joint  Laryngeal musculature Extrinsic muscles – They have one attachment on laryngeal cartilages and the other attachment on nonlaryngeal structures Intrinsic muscles – They have both origin and insertion on laryngeal cartilages  Laryngeal musculature Functions of extrinsic muscles: – Provide support for larynx and fix it in position – Major adjustments to the larynx (elevating or lowering it) – Work in concert with the articulatory movement of the tongue  Laryngeal musculature Function of intrinsic muscles: – Fine adjustments to the vocal mechanism itself – Opening, closing, tensing and relaxing the vocal folds  Intrinsic Laryngeal Muscles Adductors – Lateral cricoarytenoid muscle – Interarytenoids (IA): Transverse arytenoid muscle Oblique arytenoid muscle Abductors – Posterior cricoarytenoid muscle Glottal tensors – Cricithyroid o muscle – Thyrovocalis muscle Relaxers – Thyromuscularis  Adductor Lateral Cricoarytenoid muscle (LCA) P 190  Lateral Cricoarytenoid muscle (LCA) Attaches to the cricoid cartilage and the muscular process of the arytenoid Action: – Rotate the arytenoid cartilages medially to close the glottis. LCA muscles act to draw the muscular processes of the arytenoid cartilages anteriorly. This rotates the cartilages and results in adduction of the vocal folds. – This rotation of the arytenoids lengthens the vocal folds  Transverse arytenoid muscle Transverse interarytenoids (p 191) Band of muscle extents from the posterior surface of one arytenoid to the opposite one Action – Pull the arytenoids closer to each other medially: gliding motion approximate the vocal folds (adduct the vocal folds)  Lateral cricoarytenoid muscle and transverse arytenoid muscle increases the medial compression of the vocal folds – Medial compression: the force generated by the vocal folds at the point of their contact  Oblique arytenoid muscles Superficial to Transverse arytenoid muscle. From the base of the muscular process of one arytenoid to the apex of the opposite arytenoid (X-shape) Action – Similar function to transverse arytenoid muscle – Pulls the apex medially, adduction of the vocal folds  Abductor Posterior cricoarytenoid muscle (PCA) From the posterior cricoid lamina to the posterior aspect of the muscular process of the arytenoid cartilage Action: – Pulls the muscular process posteriorly – The only abductor muscle of the vocal fold – Antagonist (opposite function) of the lateral cricoarytenoid muscle Posterior cricoarytenoid muscle (PCA) 192 PCA are active during active exertion  abducts the vocal folds to allow more air to move into the lungs  Glottal Tensors Cricothyroid Muscle (CT) Between the cricoid cartilage and thyroid cartilage. It has two parts: – Pars recta: anterior surface (the most medial component) – Pars oblique: lateral to the pars recta Action: – Rocks the thyroid cartilage forward relative to the cricoid cartilage – Primary tensor  lengthens, elongate and tenses the vocal folds  Action: Pars recta: moves the thyroid cartilage downward (the point of movement is upon the cricothyroid joint)stretches the vocal folds Pars oblique: forward sliding movement of the thyroid cartilage  tense the vocal folds Pars recta and Pars oblique are responsible for pitch change  Thyroarytenoids (TA) The main muscular mass of the vocal folds Source of vibration May consist of two bundles of muscle fibers – Thyrovocalis Muscle (internal thyroarytenoid TA) – Thyromuscularis (external thyroarytenoid TA)  Glottal Tensors Thyrovocalis Muscle The medial muscle of the vocal folds. P 196 Action: – Tenses the vocal folds especially when it contracts with cricothyroid muscle (CT) – Draws the thyroid and cricoid cartilage farther apart (antagonistic to cricothyroid muscle) – Some fibers attach into conus elasticus. if these fibers contract, they tense the vocal folds  Relaxers Thyromuscularis Lateral thyromuscularis – Lateral to each thyrovocalis Action: Pulls the arytenoids towards the thyroid cartilage without medial rocking, makes the vocal folds thicker  laryngeal relaxer  Auxillary Musculature Thyroepiglottic muscle dilates the laryngeal opening – No apparent function in speech but it is active during the pharyngeal stage of the swallow Superior thyroarytenoid muscle relaxes the vocal folds – Superior fibers are continuous with Thyroepiglottic muscle  Auxillary Musculature Aryepiglottic muscle  protect the airway by deflecting the epiglottis cartilage over the laryngeal aditus. – Arises from the superior aspect of the oblique arytenoid muscle and continues as the muscular component of the Aryepiglottic muscle  Laryngeal muscles Extrinsic Sternothyroid Thyrohyoid Thyropharyngeus Also many muscles that are attached to the hyoid bone move the larynx: – Infrahyoid: from hyoid bone to structures below – Suprahyoid: from hyoid bone to structures above  Laryngeal muscles Extrinsic – Suprahyoids 2 digastric Stylohyoid Mylohyoid Geniohyoid 2 Extrinsic tongue muscles (strap muscles) – Geneoglossus – hyoglossus – Infrahyoids Sternohyoid  Based on function, muscles can be categorized into: – Laryngeal elevators Thyropharyngeus digastric Stylohyoid Mylohyoid Geniohyoid 2 Extrinsic tongue muscles (strap muscles) – Geneoglossus – hyoglossus – Laryngeal depressors Sternohyoid Omohyoid Thyrohyoid Sternothyroid  Digastricus Figure p 201 Function: if both parts (ant. & post) contract, the hyoid bone is pulled upward Stylohyoid Figure p 201 Parallel to the post belly of digastric  The function of all extrinsic muscles Provide stability to the laryngeal structures important to laryngeal control – The larynx (voice box) is connected to the trachea at one end and to a loosely bound bone (hyoid bone). Hyoid bone is attached to tongue muscles – Movements of the tongue are translated to the larynx