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Laryngology Embryology Anatomy Physiology Embryology • Fish gills and Branchial clefts-1st to 6th • Windpipe, trachea-glottis, framework • Swim bladder -> lungs Halsey-VS Conf-5/7/09 Embryology Halsey-VS Conf-5/7/09 Embryology of Larynx Halsey-VS Conf-5/7/09 Comparative Anatomy • Crossroads of breathing, swallowing and vocalizing • Larynx is often positioned high in neck even in non-human primates • Infant humans retain this until descent • Adult human descends Halsey-VS Conf-5/7/09 Malformations • • • • • Atresia Laryngomalacia Congenital Subglottic stenosis Laryngeal webs Branchial Clefts and Cysts Halsey-VS Conf-5/7/09 Anomalies Halsey-VS Conf-5/7/09 Anomalies Halsey-VS Conf-5/7/09 Subglottic Stenosis Halsey-VS Conf-5/7/09 Physiology • Descent of larynx occurred o Two stages Thyroid in relation to hyoid to prevent aspiration Descent of hyoid in neck in speech development • Combined respiration and deglutition o o Better in infant Poor in adult • Olfaction – consider epiglottis role Halsey-VS Conf-5/7/09 Anatomy • Pharynx o o o Naso Oro Hypo • Larynx o o o Supraglottic Glottic Subglottic • Trachea and Lungs • Esophagus Halsey-VS Conf-5/7/09 Protection Levels • First level-Epiglottis, aryepiglottic folds & arytenoids • Second level-False vocal folds • Third level-True vocal folds • Anomalies of any of this structures lead to aspiration and swallowing dysfunction • Symptoms-coughing, choking and gagging episodes, stasis of secretion, and recurrent pneumonia Halsey-VS Conf-5/7/09 Laryngopharynx Halsey-VS Conf-5/7/09 Laryngeal Framework • Cricoid cartilage o o o Only complete cartilaginous ring in the airway Strongest of the laryngeal cartilages. Lies directly below the thyroid cartilage at: C6- C7 level in adults and C3-C4 level in children Composed of hyaline cartilage, but may become partially ossified later in life (can be fractured in blunt laryngeal trauma) o Signet ring shape, widest posteriorl o An infant’s airway is most narrow at the level of the cricoid o Laryngeal Framework Anatomy Halsey-VS Conf-5/7/09 Anatomy Halsey-VS Conf-5/7/09 Muscles Halsey-VS Conf-5/7/09 Membranes Halsey-VS Conf-5/7/09 Valve Halsey-VS Conf-5/7/09 Arytenoid Rotation Halsey-VS Conf-5/7/09 Larynx Halsey-VS Conf-5/7/09 Adductors Cricothyroid-Adducts and stiffens the vocal folds Posterior Cricoarytenoid-the ONLY abductor of the vocal folds Intrinsic Muscles of the Larynx • Cricothyroid: o adducts, stiffens VF • Posterior cricoarytenoid: o ONLY abductor; Also elevates, elongates, thins VF • Lateral cricoarytenoid: o adducts, depresses, elongates, thins VF • Thyroarytenoid: o medial portion forms the vocalis muscle; adducts, shortens, depresses, and thickens VF • Interarytenoid: o adducts VF Gaps • • • • • • • • • • Above the superior pharyngeal constrictor: auditory tube (AT) levator palati (LP) ascending palatine artery (APA) Between the superior and middle constrictors: stylopharyngeus muscle (SP) glossopharyngeal nerve (IX) Between the middle and inferior constrictors: internal laryngeal branch of the superior laryngeal nerve (IL) superior laryngeal artery from the superior thyroid artery (SLA) Below the inferior constrictor: inferior laryngeal nerve ( ILN) (recurrent laryngeal branch of the vagus) inferior laryngeal artery (ILA) (inferior thyroid) Halsey-VS Conf-5/7/09 Nerves • CN IX -- Glossopharyngeal o o contains both sensory and motor fibers important for taste to posterior tongue, sensory and motor functions of the pharynx • CN X -- Vagus contains both sensory and motor fibers important for taste to oropharynx, and sensation and motor function to larynx and laryngopharynx. o important for airway protection o o • CN XII -- Hypoglossal o contains motor fibers that primarily innervate the tongue Halsey-VS Conf-5/7/09 Laryngeal Innervation • Superior laryngeal nerve: leaves CN X at the inferior vagal ganglion, travels deep and medial to ICA o o o At level of hyoid greater cornu, SLN branches into internal and external Internal SLN: through thyrohyoid membrane; innervates supraglottic larynx and pharynx and supraglottic minor salivary glands External SLN: along inferior constrictor to the CT muscle and inferior pharyngeal constrictor; also contributes to pharyngeal plexus Laryngeal Innervation • Right recurrent laryngeal nerve: originates from CN X near right subclavian artery o Travels around subclavian a. and then runs in right TE groove • Left RLN: loops around aortic arch to travel in left TE groove • RLNs give off branches to the esophagus, trachea, and inferior constrictor muscles • RLN innervates all intrinsic laryngeal muscles except CT; also subglottic sensation Innervation