Upper Airways April 15, 2020 (Dr. Vogl) Checklist Be able to describe how valve mechanisms separate the digestive and respiratory systems when eating, drinking and swallowing. Be able to identify: a) Nasal Cavities: d) Pharynx Nostrils Nasopharynx Choanae Oropharynx Laryngopharynx b) Oral Cavity Oral fissure e) Soft Palate Oropharyngeal isthmus Palatoglossal arch Palatopharyngeal arch c) Larynx Palatine tonsil Thyroid cartilage Cricoid cartilage (median) Cricothyroid ligament Epiglottis Laryngeal inlet (superior laryngeal aperture) Vocal folds Recurrent laryngeal nerves ~ 24 ~ Upper Airways April 15, 2020 (Dr. Vogl) Dissector ~ Page 1 ~ Note: • Why is a tracheostomy a surgical procedure and not an emergency procedure? 1. On the cadaver, find the thyroid cartilage and place the tip of one of your fingers in the superior thyroid notch. 2. Slowly run your finger over the laryngeal prominence and down the anterior aspect of the thyroid cartilage until you feel the membranous gap between the end of the thyroid cartilage and the cricoid cartilage below. • This is the position of the median cricothyroid ligament that connects the thyroid cartilage to the anterior arch of the cricoid cartilage. 3. Using a scalpel, make a small incision in the ligament and then put the tip of the probe through the incision into the airway. • This is a route of emergency access to the airway when the airway is blocked above the level of the vocal folds. 4. In the groove between the trachea and esophagus just inferior to the larynx, locate the recurrent laryngeal nerves on each side. • The nerves pass into the larynx by passing deep to the muscles of the pharynx and are closely related to a ligament that connects the thyroid gland to the trachea. • The nerves are motor to most muscles of the larynx (ie: they work the vocal folds) and are general sensory to the larynx below the level of the vocal folds. Basic anatomy of the larynx ~ 25 ~ Upper Airways April 15, 2020 (Dr. Vogl) Dissector ~ Page 2 ~ 5. Once you have identified the recurrent laryngeal nerves, cut through the thyroid cartilage, median cricothyroid ligament and anterior arch of the cricoid in the midline and pull the two sides apart. 6. Cut through the epiglottis and other soft tissue as the two sides are pulled apart. • This should expose the cavity of the larynx. Note the vocal folds (true vocal cords) and the vestibular folds (false vocal folds). • Also note the position of the median cricothyroid ligament to the position of the vocal folds. Hyoid bone Thyrohyoid Sternohyoid Thyroid cartilage superior belly Omohyoid inferior Cricoid cartilage belly Trachea Sternothyroid Basic musculature of upper airway ~ 26 ~.