Voice Disorders Lecture 2.pdf

SLP 286 – Voice Disorders Presentation 2 Dr. Ahmed Nagy Associate Professor , Department of Speech and Language Pathology UAEU Membranes and Ligaments of the Larynx Epithelial Lining of the Larynx • All structures are lined with Pseudostratified ciliated columnar epithelium {respiratory epithel...

SLP 286 – Voice Disorders Presentation 2 Dr. Ahmed Nagy Associate Professor , Department of Speech and Language Pathology UAEU Membranes and Ligaments of the Larynx Epithelial Lining of the Larynx • All structures are lined with Pseudostratified ciliated columnar epithelium {respiratory epithelium} • EXCEPT: The surface of vocal folds, aryepiglottic folds, anterior surface and upper half of posterior surface of epiglottis; covered with stratified squamous epithelium • All through there are many mucous glands, more numerous in the saccule (for lubrication of vocal folds) Greater deposition of Fibrous tissue {elastic fibers, fibroblast, collagenous fibers} in the subepithelial area changes the classification from membrane to ligament; in the larynx, all the surfaces are connected, there is an epithelial continuity even when the cells of the epithelium change in type. The classification of an area covered on the surface by epithelium from membrane to ligament depends on the histology of the sub epithelium MEMBRANE LIGAMENT Membranes of the Larynx The Quadrangular (4) membrane: • Extends between the epiglottis and the arytenoid cartilages • The anterior margin is attached to the lateral edge of the epiglottis • The posterior margin is attached to the arytenoid cartilages • The upper margin is reflected on a thickening in the sub-epithelium of the quadrangular membrane extending between the arytenoid cartilage and the epiglottis called the Aryepiglottic fold • The lower margin is reflected on a thickening in the sub-epithelium of the quadrangular membrane extending between the arytenoid cartilage and the thyroid cartilage called the vestibular fold {false vocal fold}. The mucosa continues downward after reflection to the saccule of the larynx. The Conus (3) Elasticus: 1. The lower margin of the base is attached to the upper margin of the cricoid cartilage. In the anterior segment of the cricoid, it connects the upper margin of the cricoid arch to the lower border of the thyroid cartilage forming the cricothyroid membrane 2. The upper free margin is a reflection of the mucosa on a thickening in the sub-epithelium connecting the vocal process of the arytenoid to the inner surface of the thyroid cartilage {the vocal ligament} the true vocal fold 3. The upper margin of the base mucosa continues upward to the saccule of the larynx Ligaments of the Larynx Ligaments of the Larynx • Thyrohyoid membrane, median & lateral thyrohyoid ligaments • Median cricothyroid ligament • Cricotracheal membrane • Hyoepiglottic ligament • Thyroepiglottic ligament • When a ligament connects two cartilages of the larynx it is intrinsic, when it connects a cartilage of the larynx to another structure it is extrinsic The Laryngeal Inlet The Laryngeal Inlet • Faces backward and upward and opens into the laryngeal part of the pharynx • The opening is bounded: • Anteriorly: The upper margin of epiglottis • Posteriorly: The arytenoid cartilages • Laterally: The Aryepiglottic folds Laryngeal Cavity • Extends from laryngeal inlet to lower border of the cricoid cartilage • Narrow in the region of the vestibular folds (Rima Vestibuli) • Narrowest in the region of the vocal folds (Rima Glottidis) Rima Vestibuli Rima Glottidis The laryngeal cavity is divided into three parts: A. Supraglottic part, the part above the vestibular folds, is called the vestibule/aditus B. The part between the vestibular & the vocal folds is called the ventricle C. Infraglottic part, the part below the vocal folds A B C Vestibular Part: • Extends from the inlet to the vestibular fold • Below, it becomes narrow as the vestibular folds project medially. • Each vestibular fold contains a vestibular ligament, the lower free margin of the quadrangular membrane stretching from the thyroid cartilage to the arytenoid cartilage Lower Part: • Extends from vocal folds to lower border of cricoid cartilage • Walls formed by the inner surface of the cricothyroid ligament and the cricoid cartilage Middle Part: • Extends from vestibular folds to the vocal folds • Laterally, a small recess between the vestibular fold & the vocal fold is called the sinus of the larynx which may extend upwards between vestibular fold and the thyroid cartilage as saccule of the larynx • The saccule contains mucous glands that moisten the mucosal surface of the vocal fold with their secretions A Spotlight on Vocal Fold Histology Voice production is a neurogenic, aerodynamic phenomena; i.e. for voice to be produced there are two unique interacting components: 1. The vocal folds are neurologically adducted against each other in the midglottic plane against the flow of expiratory air (subglottic pressure) 2. The mucosa of the vocal folds vibrate aerodynamically over the body resulting in sound production The histology of the vocal folds shows structural adaptation to the mucosal vibratory function, the vocal fold is characterized by a layered structure in which the superficial pliable layers vibrate on top of the deep, more rigid layers when the folds are adducted in the airstream of expiratory airflow. Cross Section in the Vocal Fold Layers of the Vocal Fold 1. Stratified squamous epithelium lying on a basement membrane 2. Superficial layer of the lamina propria: This layer consists of loose, fibrous components and extracellular matrices that can be compared to soft gelatin. It is also known as Reinke’s space. • Layers 1 & 2 are known as the cover which is responsible for mucosal vibration 3. Intermediate layer of the Lamina Propria, which is made of longitudinal elastic fibers running along the length of the vocal fold from the vocal process to the thyroid cartilage attachment 4. Deep layer of the Lamina Propria which is made of longitudinal collagenous fibers running along the length of the vocal fold from the vocal process to the thyroid cartilage attachment • Layers 3 & 4 are the transitional part of the fold, attaching the cover to the deeper layer and supporting the mucosa during vibration 5. The Thyroarytenoid muscle forms the deep layer of the vocal fold, providing support for the superficial layers and maintaining vocal adduction against the force of expiratory air. Thank you