Presentation on theme: "Phonation and Laryngeal Anatomy and Physiology"— Presentation transcript:
1Phonation and Laryngeal Anatomy and Physiology Nothing is ever said on the stage without a reason. There are no exceptions Charles Waxberg
2The original use of the larynx was to keep us alive through breakfast The original use of the larynx was to keep us alive through breakfast. Its main function is stop solids and liquids from entering the trachea and choking us to death. Its secondary functions are to bear down, phonation and speech. The larynx of humans and great apes in infancy is higher in the neck so that they can breathe and suckle at the same time. In humans it descends before the age of two.
3What the Larynx is for To stop food/liquid from entering the lungs To Bear DownWhile ExpellingDefecationChildbirthWhile LiftingPHONATION
15The thyroid rests superiorly on the cricoid and attaches posterior-laterally at the cricoid’s inferior articulator facets. This attachment (the cricothyroid joint) hinges the cricoid and thyroid allowing their anterior sides to adduct, changing vocal fold length.
16MovementThe arytenoid cartilages, two pyramid shaped cartilages rest on the cricoid at the cricoarytenoid joints and move in two distinct ways:1.) To pivot (rocking) the posterior ends of the arytenoids away from each other, adducting the anterior ends or the reverse so the anterior ends abduct, and…2.) Sliding the arytenoids on an anterior-posterior path.Since the vocal folds are attached to the anterior ends of these cartilages (at the vocal process) any movement in them will change the folds’ shape, tension and relationship to each other thereby affecting phonation.
18Composition of the Larynx (Con’t) Composed of Muscle:Extrinsic Laryngeal MusclesIntrinsic Laryngeal Muscles
19Extrinsic Muscle TWO Groups of Extrinsic Muscles: Suprahyoids – Attach to points above the Hyoid (Jaw, Skull and Tongue) when they contract they raise or elevate the Larynx eg SwallowingInfrahyoids – Attach to points below the Hyoid (one connects to the thyroid, however the others connect to the sternum and the scapula) when they contract they lower or depress the Larynx
28Vocal Folds Muscle Membrane External Thyroarytenoids – inserts into the muscular process on the Arytenoids and the Thyroid notch (shorten and adduct)Internal Thyroarytenoids – inserts into the vocal process on the Arytenoids and the Thyroid Notch (shortens and stiffens), act antagonistically to the CricothyroidsMembrane
30Membranes False Vocal Folds – Ventricular folds Laryngeal Ventricle Conus Elasticus (interconnects the thyroid, cricoid and arytenoids cartilages)Lamina propria (mucosal cover of the vocalis muscle) – can vibrate independently of the vocalis muscleVocal Ligament – the thread like collagenous fibers of the deep layer of the lamina propria
31Relaxors and TensorsExternal Thyroarytenoid – Relaxor, shortens and adductsInternal Thyroarytenoid – Tensor, shortens and stiffensCricothyroid Muscles – Tensor, lengthens and stiffensPitch is determined by Relaxors and Tensors
33Fundamental Frequency Phonation is made up of a fundamental frequency or Fo (the number of times the folds open and close per second-CPS) and harmonic multiples of the Fo (two times the Fo, three times, four times etc.) that fall in intensity (volume) in an inverse relationship as the harmonics rise in frequency or as the pitch rises the volume falls.
34Fundamental Frequency INTENSITY(VOLUME)FREQUENCY(PITCH)
35PitchFundamental frequency (average: baby 500Hz, children Hz men 125Hz women 200Hz) is primarily affected by applying more or less longitudinal tension to the VF using:CricothyroidsTension in the vocalis muscleORAdjustments in vertical tension – depressing or elevating the Larynx via suprahyiod and infrahyoid muscles
36Vocal Fold Tension, Elasticity and Movement Thicker or thinnerShorter or longerOpen or closeIntermediate positionsStiff or elasticMovement:Bronx Cheer or Raspberry– “the sound is that or air escaping in rapid bursts, not the sound of the lips moving” – Borden and Harris. Aerodynamic forces acting on the elastic body of the lips
37ADMET – Aero Dynamic Myo-Elastic Theory Glottal vibration is the result or refers to interaction between aero-dynamic forces and vocal fold muscular action.Sub-Glottal PressureBernoulli Effect – set vocal folds into vibration due to the elasticity of the folds (elastic recoil – the force which restores any elastic body back to its resting place)Muscular Force – Muscles act to bring the folds together so they can vibrate, and muscles regulate their thickness and tension to alter fundamental frequency. Folds are FULLY or PARTIALLY ADDUCTED for phonation
38Bernoulli EffectAn increase in velocity results in a drop in the pressure exerted by the molecules of moving gas or liquid, the pressure drops being perpendicular the direction of the flow
39Schematic showing the Bernoulli Effect Schematic showing the Bernoulli Effect. The arrows indicate movement of pressure. As the air moves through a narrowing, inside pressure drops and outside pressure increases pulling the sides inward.
40Glottal CycleVertical Phase Difference – vocal folds open at the bottom first. As top part opens bottom part closes. Wave like motion