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TO REVIEW SKELETAL STRUCTURE OF LARYNX 6 Cartilages: Cricoid Thyroid Arytenoid Corniculate Cuneiform Epiglottic 1 Bone: Hyoid Basic Structure/Layers of Vocal Folds: Epithelium Lamina Propria Thyroarytenoid (Vocalis) Muscle Cricoid Cartilage (Anterior) Thyroid Cartilage (Anterior) Arytenoid, Corniculate, and Cuneiform Cartilages Epiglottic Cartilage (Anterior, then Sagittal) Hyoid Bone (Anterior) MOVING ON.... INTRINSIC LARYNGEAL MUSCLES: All Paired Arytenoid Muscles Interarytenoids (transverse, oblique) Thyroarytenoid Muscles Cricoarytenoid Muscles (posterior, lateral) Cricothyroid Muscles INTRINSIC LARYNGEAL MUSCLES: All innervated by recurrent laryngeal nerve Except: Cricothyroids innervated by external branch of superior laryngeal nerve Intrinsic Muscles Anterior-Superior View Intrinsic Muscles Posterior-Superior View INTRINSIC MUSCLES: OPENING & CLOSING THE FOLDS INTRINSIC MUSCLES: CLOSERS/ADDUCTORS Lateral Cricoarytenoids (LCA) Interarytenoids (IA) Transverse Oblique INTRINSIC MUSCLES: OPENERS/ABDUCTORS Posterior Cricoarytenoids (PCA) Pull the arytenoids laterally to open the glottis INTRINSIC MUSCLES: LENGTHENING AND SHORTENING THE FOLDS INTRINSIC MUSCLES: LENGTHENERS/THINNING Pitch/Frequency of voiced sounds is largely controlled by varying the length of the vocal folds. As the folds are lengthened, their mass per unit length is reduced. Consequently, they vibrate faster when lengthened. The vocal folds are attached to the thyroid cartilage at the front and the arytenoid cartilage at the back. The arytenoid cartilage, however, rides on the cricoid cartilage. So the length of the folds is mainly achieved by using the Cricothyroid (CT) Muscles, which rock the cricoid cartilage backward and upward, causing rotational movement of the thyroid cartilage (moving it slightly forward and tipping its front end downward). The cricothyroid muscles also pull the arytenoid cartilages slightly backwards, as they ride on the cricoid cartilage. These movements enabled by the cricothyroid muscles both lengthen and thin the vocal folds. INTRINSIC MUSCLES: LENGTHENERS/THINNING INTRINSIC MUSCLES: SHORTENERS/THICKENING Shortening of the vocal folds occurs when the thyroarytenoid muscles (TA) contracts. When the thyroarytenoid muscles are not opposed by the thyrocricoid muscles (the lengtheners), they exert a shortening-thickening-laxing influence on the vocal fold cover tissues. TO RECAP: Openers/Abductors: PCA Closer/Adductors: LCA & IA Lengtheners: CT Shorteners: TA IMPORTANT TO REMEMBER: The Lengtheners/Shorteners and Openers/Closers all work in constant relationship to each other. http://getbodysmart.com/ap/respiratorysystem/larynx/menu/animation.html