Anatomy and Physiology Voice Disorders PDF

Anatomy and Physiology Voice Disorders COMD 6387 Your job as an SLP is to balance all 3 major subsets. What is the difference between phonation and...

Anatomy and Physiology Voice Disorders COMD 6387 Your job as an SLP is to balance all 3 major subsets. What is the difference between phonation and resonance in written terms? Voice Phonation: sound that is produced as a byproduct of the vocal folds moving Resonance: the modification of sound depending on Production other factors such as size and shape of vocal folds, pharyngeal cavity, nasal cavity, oral cavity etc. Respiration Phonation Resonance Power Source Filter Lungs Ribs Abdomen Vocal folds Vocal tract  Lungs Made of highly elastic material and very few smooth muscle fibers Lungs rely on active muscle/thoracic contractions, lungs themselves are passive  Function of Pleura Lining of the Lung Pulling forces between the inner lining of the thorax and the outer lining of the lungs keeps them together The pluera is negative compared to atmosphere pressure. Surface tension also keep lungs in place. If we took the lungs out of the body the lungs would collapse and the thorax ______________. will expand ??? Can you explain why?  Muscles of Quiet Inspiration Diaphragm Dome-shaped; flattens on inspiration External Intercostals When they contract Muscles that they have an elevate the ribs enlarging ribcage. upward pull on the ribs they attach to  Muscles of Forced Inspiration Do I need to be able to label, explain what each does, memorize them??? 1. Sternocleidomastoid Muscle Sternocleidomastoid: Elevates the sternum. 2. Scalene Muscle Group Scalene muscles: Elevate the first and 3. Subclavius second ribs. 4. Pectoralis Major Pectoralis major and minor: Assist in 5. Pectoralis Minor elevating the ribs when the arms are fixed. 6. Serratus Anterior Serratus anterior: Helps expand the rib cage. 7. Costal Levators Latissimus dorsi: 8. Serratus Posterior Superior Assists in elevating the lower ribs. 9. Latissimus Dorsi Generally know these are the muscles. Be able to name them.  Quiet/Passive Expiration Passive expiration is accomplished by nonmuscular forces (recoil forces) Potential (stored) energy resulting from the increased dimension is released Think of the recoil of a stretched spring  Muscles of Active Expiration Responsible for decreasing the dimensions of the thoracic cavity. Abdominal muscles of expiration can push up on diaphragm, thus, reducing vertical dimension of thorax Thoracic muscles of expiration act upon the ribs, essentially depressing them to reduce thoracic dimensions.  Muscles of Active Expiration Rectus abdominus External obliques Internal obliques Transverse abdominus Serratus posterior inferior Internal intercostals In general know them. TLC = TV + IRV + ERV + RV + Dead Air (leftover air in lung capacity - 100ccs) VC = TV + IRV + ERV The amount of Important TV + RIV = IC inspiration you can for take after a normal as deep as air you can inhale inspiration. SPEECH: 1. TV 2. IRV 500 ml exchanged 3. ERV = VC Amount of volume inhaled or exhaled The amount of air during normal Female 2-3 remaining in lungs breathing. after normal Makes 3-4 exhalation. The air liters remaining in lung to The amount of air you prevent it from can breath out after a How much collapsing + residual amount of air you can exhale in your control volume. normal expiration. air available Capacity is made up of 2 or more The amount of air left in the to volumes. Vital capacity it refers to the lung after maximum maximum amount of air you can exhale yell/scream after inhalation. This is the most important exhalation. But we cannot etc. one because you want to know how much your voice client can exhale. There is a control it, it is there to prevent normal amount expected by gender, lung collapse. It goes up as weight & age. we get old. ERV + RV = FRC 2-3 volumes How much air in your lung. Hard to follow? The relationship b/w lung capacity and lung volume. Total lung capactiy you add everything tofether.  Breathing in Upright and Supine Positions Breathing is influenced by the position that you place your patient in when you are working with phonation or speech.  Expiration Rest Inspiration UPRIGHT VERSUS SUPINE Gravitational Effect is in the Harder to preform expiration passively. Expiratory Direction Gravity pushes down on ribs and lung so it's harder to exhale, forcing the diaphragm to work harder. What about generalization of treatment ? It is questionable if it can generalize. Some old school therapists might still do sessions laying down. More focused will be placed on breathing rather than generalizing what was learned in voice treatment.  Major Function of the Larynx Sphincteric muscular(UES & LES) organ designed for the protection of the airway Major Functions - Air way protection - Swallowing - Phonation  Basic Design Cylindrical tube with soft tissue and muscle folds extending medially from the lateral internal walls Adults: C3-C6 Children: C4  Won't be quizzed on it b/c it is review from dysphagia. Function of the Aryepiglottic Sphincter 3 levels of airway protection during swallowing. First one is aryepiglottic folds. Separates the pharynx from the laryngeal vestibule. Ill-defined muscle fibers, approximate during swallowing and other sphincteric movements. Tilts the epiglottis forward. Coronal View  Function of the Ventricular Sphincter Protects the airway during swallowing. In extreme cases when true vocal fold cannot tense, false vocals folds will squeeze to create phonation. The false vocal fold helps apply pressure when needed (ex. lifting a heavy box) Approximation of the ventricular folds permits ventricle = heart chamber increase of intra-thoracic pressure for coughing, sneezing, defecation, urination, regurgitation, and lifting. Protects the airway during swallowing. Also used for substitute voice. Vocal phonate sounds very flat without phonation and articulation. That's what makes you sound like you.  Function of the True Vocal Fold Sphincter Protects the airway during swallowing. Major vibratory source for voice.  Base of tongue Epiglottis FVC Aryepiglottic folds Vocal folds Pyriform sinus Pyriform sinus Arytenoids Laryngeal Framework: 9 Cartilages, 3 Paired and 3 Unpaired. 1 Bone. cricoid = signet ring thyroid = Adam’s Apple epiglottis = leaf arytenoids = pyramids corniculates = flagpoles Paired Cartilages What are these? cunieforms = floaters hyoid bone = superior anchor  Ligaments and Membranes Don't to need to know more than this The cartilaginous framework is attached by ligaments located at each articulating joint. Membranes expand from each ligament tissue connecting bones, joints, & organs covering the framework and filling the spaces not occupied by laryngeal muscles.  Extrinsic Laryngeal Muscles Responsible for elevating and lowering the larynx in the neck during respiration, phonation, and swallowing.  Infrahyoid Muscles Lower the Larynx Thyrohyoid Omohyoid Sternothyroid Sternohyoid  Suprahyoid Muscles Raise the Larynx mylohyoid digastric (anterior and posterior bellies) geniohyoid stylohyoid stylopharyngeous  Intrinsic Laryngeal Muscles Both attachments are located on the laryngeal framework.  Functional Divisions of Intrinsic Laryngeal Muscles abductor Open = posterior cricoarytenoid adductors Close = lateral cricoarytenoid transverse arytenoid oblique arytenoids thyroarytenoid relaxers = vocalis/thyroarytenoid tensors = cricothyroid (pars recta and pars oblique)  Abductor posterior cricoarytenoid  Adductors lateral cricoarytenoid transverse arytenoid Connects arytenoid and thyroid. Inner most muscle. oblique arytenoids thyroarytenoid  Relaxers thyroarytenoid – vocalis  Tensors cricothyroid – Pars rectus – Pars oblique  Vocal Fold Microstructure (Hirano, 1977,1981) Hirano’s discoveries of the layered structure of the vocal fold led to a revolutionary change in voice care procedures. It is this membranous structure that vibrates during phonation. The integrity of vibration is dependent upon this healthy mucous membrane.  Vocal Fold Microstructure 5 histologic layers Layers arranged from thin, pliable first layer to progressively stiffer layers Important microcellular transition zone between the epithelium and lamina propria responsible for cell generation b/c VF has mechanical force Hirano’s classification of vocal folds Epithelium Superficial Intermediate Lamina Deep Propria Body  Vocal fold contd. Epithelium Squamous anthemis cells Thin, stiff capsule that maintains the integrity of the fold shape - the skin Superficial layer of the lamina propria Loose, fibrous components similar to a mass of soft gelatin (Reinke’s space) Lesions specific to this layer, ex. smokers get Reinke's Edema Intermediate layer of the lamina propria Elastic fibers similar to a bundle of soft rubber bands More dense, less loose but still very elastic  Vocal fold contd. Deep layer of the lamina propria Collagenous fibers similar to a bundle of cotton thread Vocalis muscle The main body of the vocal fold. Similar to a bundle of stiff rubber bands.  Mechanical Classification of the Vocal Fold Cover Cover - epithelium and superficial layer of the vocal fold cover (passive) Transition - intermediate and deep layers of the lamina propria (passive) Body - vocalis muscle (passive and active) Transition  Basement Membrane Zone (BMZ) (Gray, 1991) Transition area between the epithelium and the superficial layer observed only through electron microscopy. Thought to be a prime injury site due to mechanical trauma and fold shearing.  Definition: A gel-like mixture of water, proteins, and sugars that supports and regulates tissues and organs Extracellular matrix The ECM plays a crucial role in cell adhesion, cell-to-cell communication, and differentiation. It also acts as a scaffold for tissue and organ structure, influencing tissue repair and development12 All layers of LP contain an extracellular/noncellular matrix (ECM) Supports vibrating vocal fold supercial layer deeper layer? Composed of proteins (collagen, elastin), carbohydrates and lipids Different protein types allow for elasticity during vibration, tensile strength during strain, tissue viscosity etc. Certain proteins (fibronectin) are activated for tissue regeneration and wound healing  Connective tissues Two tissue structures support vocal folds at points of mechanical stress – Anterior and posterior macula flava (bundles of fibers and fibroblasts) Anchors membranous LP at vocal ligament to thyroid and arytenoid cartilages – Conus elasticus Expends from subglottal tracheal wall to inferior boarder of tracheal ligament Subglottic tracheal wall into inferior border of vocal ligament KNOW: Intrinsic muscles, especially know the function of intrinsic muscles Microstructure of vocal folds & different layers of vocal fold  Neurology Neurology of voicing? What is this referring to? Important nerves? Vagus nerve branches Recurrent laryngeal nerve – The traveling nerve – Innervates all of the intrinsic laryngeal muscles except the cricothyroid Superior laryngeal nerve, internal (sensory) and external branches (cricothyroid)  Blood supply and secretions Arteries branching from the external carotid artery Venous return through the jugular vein Predominant blood supply in the intermediate and deep layer of the LP and vocalis muscle Serous and mucous glands are located in tissues lateral, superior and inferior to the vocal folds  Central Nervous System control Still not completely understood because of absence of a representative animal model Larynx involved in phonation, respiration, airway protection, thoracic stabilization and deglutition making the study more difficult Sensory receptors in the laryngeal mucosa and respiratory passages send information to the medulla (afferent)  CNS control contd. Other sensory fibers continue to a region of the midbrain (periaqueductal gray) Some evidence shows sensory fibers that continue to the thalamus and primary sensory area Motor (efferent) commands start in primary motor cortex continue to the brainstem, spinal cord and continue to the PNS Neuronal units in the CNS maybe specific to laryngeal task  Neurochronaxic Theory (Husson) (1 out of 3 theories on vocal fold vibrations) States that vocal fold vibration is almost totally dependent on the rate of neural impulses received by the laryngeal muscles Even though nerves can fire (send impulses) quite fast, the rapid pattern of vibration observed during production of high frequencies can not be explained by the rate of nerve impulse – One side of recurrent nerve is longer – Vocal folds do not vibrate in the absence of an airstream Not possible b/c vibration of vocal fold is much faster than neural firing  refers to muscles refers to air Myoelastic-aerodynamic Theory of Phonation (Van den Berg, 1958) Widely accepted Takes into account the laws of physics which regulate movement/control of air molecules (Aerodynamic) and muscle activity (Myoelastic) – Know the basic concept of Bernoulli effect – Know and describe the steps of the myoelastic- aerodynamic theory.  Bernoulli effect The speed of a fluid (air or liquid) increases, its pressure decreases. Driving next to 18 wheeler, the pressure drops b/c of the speed and it can feel like your car is being pulled to the 18 wheeler.  Myoelastic-aerodynamic Theory of Phonation (Van den Berg, 1958) 1. Vocal folds adduct and approximate at the midline. 2. Sub-glottic air pressure builds against the resistance of the approximated folds. 3. Pressure overcomes the resistance forcing the folds apart and releasing one puff of air.  Myoelastic-aerodynamic Theory of Phonation cont. 4. Release creates a sudden drop in pressure at the level of the folds resulting in a suction called the Bernoulli Effect. 5. The suction, along with the static positioning of the approximated folds begin to draw the folds back together. 6-7. The closer the folds draw, the greater the suction until the folds approximate again completing one vibratory cycle.  Titze (1994) Phonation Theory Expansion It's not just lungs but aerodynamics and the spaces around the lungs causing the vocal folds to vibrate. Pressure and flow interchanges provided by the pulmonary airstream at 3 sites maintains vocal fold vibration: 1. Subglottal region directly beneath the folds where the leading edge is set into motion 2. Intraglottal space directly between the folds with continuing pressure and flow changes as the folds move back and forth Titze's Phonation Theory explains how your vocal cords vibrate to produce sound when you speak or sing. Here's a simple breakdown: 1. **Air Pressure from Lungs**: The air you push out from your lungs creates pressure right below your vocal cords, which makes the edges of the vocal cords start to move. 2. **Air Flow Between Vocal Cords**: As your vocal cords move back and forth, the air between them keeps changing in pressure and flow, helping them continue vibrating. 3. **Air Above the Vocal Cords**: The air just above your vocal cords also plays a role. As the vocal cords vibrate, they cause the air above them to move in waves, compressing and expanding. This movement of air above the vocal cords actually helps keep them vibrating in a smooth, continuous way. Titze's main idea is that this interaction between the air pressure below, between, and above the vocal cords is key to maintaining the vibration, which is how sound is produced. His theory adds to the earlier understanding by emphasizing the importance of the air above the vocal cords in sustaining the vibration.  Titze Phonation Theory cont. New edition to theory: 3. Supraglottal air column immediately above the folds where the air molecules are alternately compressed and rarefied in a delayed response to the alternate pressure and flow fluctuations modulated by the vibrating vocal folds. The excitation of the supraglottic air column facilitates a top-down loading effect that helps sustain fold oscillation. This is the major addition to the myoelastic-aerodynamic theory.  Important Facts to Remember … The vocal folds do not adduct and abduct during phonation because there is separate muscle contraction for each movement During a sustained sound = not abduction/adduction The vocal folds open and close as long as the vocal folds are in the approximated position and there is sufficient buildup of pressure below them When you speak or sing, your vocal cords don't need separate muscle actions to open and close each time they vibrate. Instead, they stay close together, and the air pressure from your lungs pushes them open. Then, they close back up on their own. This process keeps repeating as long as your vocal cords stay in the right position and there's enough air pressure pushing from below. So, it's the air pressure, not the muscles, that keeps them opening and closing during phonation (sound production).  Control of Fundamental Frequency (Fo) Here's a simple explanation of how the pitch of your voice is controlled: Fundmental Freuqncy = main pitch your voice is usually at 1. **Vocal Cord Length and Tension**: vocal fold length and tension - **Higher Pitch**: When certain muscles (CT muscles) make your vocal cords longer, the edges become thinner and tighter, causing the pitch of your voice to go up. - **Lower Pitch**: When other muscles (TA muscles) – when folds lengthen due to contraction of make your vocal cords shorter, the edges become looser and rounder, which lets them vibrate more widely and the CT the medial edge thins and stiffens lowers the pitch of your voice. 2. **Air Pressure (Psub)**: and pitch increases - As you raise the pitch of your voice, the pressure of the air coming from your lungs also needs to increase to – when folds shorten due to contraction of support the higher pitch. 3. **Vibration and Pitch**: the TA, cover tension decreases rounding - The faster your vocal cords vibrate, the higher the pitch. However, when the pitch is lower, the vocal cords the medial edge allowing greater can move with more force or amplitude. So, when you sing or speak in a lower pitch, your vocal cords vibrate amplitude of vibration more strongly. – Psub increases proportionally with increased Fo in the mid-range– why? – Vibratory amplitude is inversely proportional to the rate of vibration, increasing with lower pitch The higher the pitch, the faster the vocal folds move and the longer they are. The lower the pitch, the more forceful the vocal folds move and the shorter the vocal folds are. Psub = subglottal pressure. Fo = fundamental frequency. Vibratory amplitude = how much the vocal folds move. Rate of vibration = how many times they move As you increase the pitch (especially in the middle range of your voice), the air pressure from your lungs (Psub) also needs to increase. This extra pressure helps the vocal cords vibrate faster to produce the higher pitch. When you sing or speak at a lower pitch, your vocal cords vibrate more slowly, but they move with more force or amplitude. Conversely, when the pitch is higher, the vocal cords vibrate faster, but the amplitude of their movement is smaller.  Control of Intensity The closed phase of the vibratory cycle is increased (medial compression – with what muscles?) and the subglottal pressure is increased creating a wider amplitude of vibration thus increased intensity Vocal tract tuning can also influence the loudness of the glottal source Here's a simplified explanation of what this means: 1. **Control of Intensity (Loudness)**: - To make your voice louder, your vocal cords stay closed for a longer part of each vibration cycle. This is called the "closed phase." - **Medial compression** refers to how tightly your vocal cords are pressed together. Certain muscles (like the lateral cricoarytenoid and interarytenoid muscles) help squeeze the vocal cords together more tightly. - When your vocal cords are tightly closed and there is increased air pressure below them (subglottal pressure), the vocal cords will vibrate with more force, creating a wider movement (amplitude). This stronger vibration makes your voice louder. 2. **Vocal Tract Tuning**: - The shape and position of your vocal tract (your throat, mouth, and nose) can also affect how loud your voice sounds. By adjusting how you shape your vocal tract, you can amplify the sound coming from your vocal cords, making your voice louder. For example, opening your mouth wide and raising your soft palate. In short, you control how loud your voice is by adjusting how tightly your vocal cords close and by using your vocal tract to enhance the sound.  Vocal tract The vocal tract begins just above the vocal folds and ends where? Our “voice” consists of sound waves produced by the vibration of the vocal folds (source) that resonate through the vocal tract (filter) The size and shape of the various cavities of the vocal tract will influence the final acoustic output – “voice” If we didn’t have the vocal tract our acoustic output would just be a buzzing sound The vocal tract begins just above the vocal folds and ends at the lips. It includes the throat (pharynx), mouth (oral cavity), and nasal passages (nasal cavity) up to the point where the sound exits the mouth.  Vocal tract The resonating sound waves that emerge from our vocal folds resonate at specific frequencies (mathematical formula for how sound resonate in a tube) and give us formant frequencies as well These formant frequencies allow us to make sounds that differ from one another and can add to the “richness” of a tone What problems could occur in the vocal tract that would detract from the quality of the voice? The shape and size of your vocal tract change If there are issues in the vocal tract, such as how these sound waves resonate or bounce blockages, infections, or structural problems, around. they can affect how sound waves resonate. These resonances create specific frequencies This can make your voice sound weak, called formants, which help shape the different muffled, or less clear, reducing its overall sounds we make (like vowels). quality.  Dependents of Vocal Quality efficiency of the vibratory characteristics of the vocal folds filtering characteristics of the supraglottic vocal tract adequate and consistent subglottic pressure and flow source Here’s a simple explanation of what affects vocal quality: 1. **Vibratory Characteristics of the Vocal Folds**: - How well your vocal cords vibrate affects your voice. If they vibrate smoothly and efficiently, your voice sounds clear and strong. 2. **Filtering Characteristics of the Vocal Tract**: - The shape and size of your throat, mouth, and nasal passages change how sound waves are filtered and shaped. Good filtering makes your voice sound more distinct and pleasant. 3. **Subglottic Pressure and Flow**: - The pressure and airflow from your lungs that push through your vocal cords need to be steady and strong. This helps your voice stay consistent and powerful. In short, your vocal quality depends on how well your vocal cords vibrate, how your vocal tract shapes the sound, and how well your lungs provide air pressure and flow.  Vocal registers/ phonation modes Falsetto (loft) – High fundamental frequency, strong CT contraction, slightly abducted vf, vibration mainly at medial edges, high flow and Ps Modal (chest) – Mid frequency ranges, contracted TA, rounded vf edges, large vibratory amplitude and mucosal wave Glottal fry (pulse) – Low frequency, irregular vf vibration, low subglottal pressure, limited flow.  The Pediatric Voice: Special Considerations ▪ The most important consideration in pediatric population is the preservation of airway. ▪ The larynx/airway is almost the most important system of the entire infant. ▪ Newborns only breathe through the nasal passages during the first few months of life – allowing them to breathe and swallow at the same time.  Position of the Larynx ▪ In an adult the larynx sits opposite approximately the fifth or sixth cervical vertebral body ▪ In a newborn the larynx sits opposite approximately the second and third cervical vertebral body ▪ As the child ages, the larynx will slowly descend  Laryngeal Structures ▪ In the pediatric larynx, the Immature Mature thyroid notch is not prominent as it is in the adult larynx. It is obscured Hyoid Cartilage by the overlapping hyoid Overlaps bone Thyroid ▪ The cricoid cartilage of the No Vertical Prominence pediatric larynx is also not in Thyroid prominent Cricothyroid Membrane is a slit Anterior View  Laryngeal Structures The aryepiglottic folds and the arytenoid cartilages are large relative to other laryngeal structures It is estimated that 50% of infants have an omega shaped large epiglottis arytenoids Child Adult  Vocal Folds ▪ Length of the entire vocal fold in newborns Adult vocal folds-normal is about 1.25-3.0 mm, with gender difference up to the age of 10. ▪ In adults, vocal fold length is about 17-21 mm in males and 11-15 Pediatric vocal folds-normal mm in females.  Pediatric Larynx Newborns do not have a vocal ligament (intermediate and deep layers of the lamina propria) and a larger membranous tissue to cartilage ratio This allows better airway protection and more stability Consider you have a patient who arrives with complaints that his voice is breathy and weak. He also complains of slight difficulty (coughing) when swallowing. He says this all began 1 month ago. You complete a stroboscopic examination and notice no movement (abduction or adduction) of the left vocal fold (left true vocal fold paralysis). Question 1: Damage to what branch of the vagus would have caused this? Question 2: What muscles are not receiving innervation to ABduct? to ADduct? Question 3: What, in this patient's history, might cause such symptoms? What questions would you ask to find out? Question 4: Why is swallowing impaired? Ask the pt if he's had recent surgery? His airway protection is compromised.