<p> VOICE DISORDERS Chapter 11</p><p>***Review notes from AUS 304, Anatomy & Physiology of Phonatory System ***Chapter 11 – Anatomy review at beginning of chapter  Structures of the Laryngeal Skeleton (Table 11.1)  Structures within the Larynx (Table 11.2)  Structure of the True Vocal Folds, & Hirano’s Cover-Body Model (Table 11.3).  Intrinsic Muscles of the larynx (Table 11.4)  Innervation of the Larynx – (Table 11.4)</p><p>Anatomy of the Larynx</p><p> The larynx or voicebox is situated on top of the trachea where the aerodigestive tract splits into two separate pathways.  It consists of a framework of cartilage with surrounding soft tissues  It serves three important functions:</p><p>1. Control of airflow during breathing 2. Protection of airway (by closing off the trachea during swallowing) 3. Production of sound for speech</p><p>Laryngeal Cartilages </p><p>Cricoid: </p><p> Ring-shaped cartilage that sits on top of the trachea</p><p>Thyroid: </p><p> Cartilage positioned on top of the cricoid cartilage</p><p> Shield-shaped and most prominent of the laryngeal cartilages</p><p> The cricothyroid joint permits rocking and gliding motion of the thyroid</p><p>Epiglottis: </p><p> Leaf-shaped cartilage that covers the laryngeal vestibule during swallowing</p><p>Arytenoids: </p><p> Two small pyramidal shaped cartilages that sit on top of the cricoid (form the cricoarytenoid joint) </p><p> Play a critical role in phonation</p><p> The true vocal fold attach at one end of the arytenoids</p><p> Many muscles attach to muscular process (on the back of the arytenoids) and can move in different ways: Laryngeal Muscles Movement of larynx is controlled by two groups of muscles:</p><p>1. Intrinsic: muscles that move vocal folds and other muscles within larynx 2. Extrinsic: position the larynx in the neck also called “strap muscles”</p><p>Intrinsic Muscles:</p><p>PCA or posterior cricoarytenoid: </p><p>LCA or lateral cricoarytenoids: </p><p>IA or interarytenoids: </p><p>TA or thyroarytenoid: </p><p>CT or cricothyroids: Laryngeal Spaces </p><p>Glottis: Refers to the space between the vocal folds</p><p>Anterior commissure: Where the VFs attach to the thyroid cartilage </p><p>Posterior glottis: </p><p>Vocal Folds (See Hirano’s Cover-Body Model)</p><p>Cover = Mucosa Body = Muscles</p><p>1. Cover has two layers: (see web cross-section fig) 1.Epithelium: </p><p>2.Lamina propria: </p><p>2. Body: made up of thyroarytenoid muscle Vocal Fold Motion (web fig mucosal wave)</p><p>1. Vocal folds at rest are:</p><p>2. For speech, muscle contraction brings the folds together</p><p>3. Pressure builds</p><p>4. Folds are blown apart</p><p>5. Folds come back together via 2 things:</p><p>6. Cycle repeats Mucosal wave: folds do not open all at once; rather the bottom part opens first then the top part opens. A good mucosal wave is necessary for the folds to open in a uniform and symmetric fashion for optimal voice quality.</p><p>Neural Control of Larynx (See Fig) Vagus Nerve (CN X) has three branches that innervate the larynx.</p><p>1. Pharyngeal Branch</p><p>2. Recurrent Laryngeal Nerve (RLN)</p><p>3. Superior Laryngeal Nerve (SLN): as 2 branches of its own:</p><p> a. Extrinsic</p><p> b. Intrinsic Physiology of the Larynx</p><p>1. Changing Frequency of VF vibration heard as “Pitch”</p><p>Three mechanisms alter the frequency of vocal fold vibration:</p><p>1. Mass</p><p>2. Length</p><p>3. Tension</p><p>2. Changing Loudness</p><p>1. Increase subglottal pressure (pressure below the VFs)</p><p>2. Increase medial compression of the folds</p><p>3. Increase amplitude of articulatory movements (doesn’t play as crucial a role as other 2)</p>