The term “airway” refers to the nasal and oral cavities, pharynx, larynx, trachea, and principal bronchi.
The nasal cavities are divided by the nasal septum. The roof of the nasal cavity is the cribriform plate. The lateral wall is the origin of the turbinates. Openings in the lateral wall communicate with paranasal sinuses. The greater and lesser palatine nerves innervate the turbinates and most of the nasal septum, and the anterior ethmoid nerve. The ethmoid nerve provides sensation to the nares and the anterior third of the nasal septum. The palatine nerves arise from the sphenopalatine ganglion.
The roof of the mouth consists of the hard palate anteriorly and the soft palate posteriorly. The tongue makes up most of the mouth floor. Temporomandibular joint (TMJ) rotation initiates mouth opening, followed by sliding of mandibular condyles within the TMJ.
The pharynx is a fibromuscular tube that extends from the base of the skull to the lower border of the cricoid cartilage. The oropharynx is innervated by branches of the vagus, facial, and glossopharyngeal nerves. The glossopharyngeal nerve gives sensory innervation to the posterior third of the tongue, vallecula, anterior surface of the epiglottis, walls of the pharynx, and tonsils.
As seen in Figure 152-1, the larynx consists of nine cartilages: three single (thyroid, cricoid, and epiglottic) and three paired (arytenoid, corniculate, and cuneiform). Together, these house the vocal cords. The thyroid cartilage helps to protect the vocal cords. The intrinsic and extrinsic muscles of the larynx control the laryngeal structures. The cricothyroid membrane is located anteriorly between the thyroid and cricoid cartilages, directly subcutaneous to the skin. Any needle punctures or incisions made to this membrane should be made in the inferior third because the superior cricothyroid arteries course through the upper two-thirds. The laryngoscopic view of the larynx is shown in Figure 152-2.
Anatomy of the larynx. (Reproduced with permission from Lalwani AK. CURRENT Diagnosis & Treatment in Otolaryngology–Head & Neck Surgery, 3rd ed. New York: McGraw-Hill; 2012.)
Laryngoscopic view of the larynx. (Reproduced with permission from Longnecker DE, Mackey SC, Newman MF, et al, eds. Anesthesiology. 3rd ed. New York: McGraw-Hill; 2018.)
The vagus nerve provides the sensory and motor innervation of the larynx (Figure 152-3). Its two major branches are the superior laryngeal nerve and the recurrent (inferior) laryngeal nerve. The superior laryngeal nerve provides sensory innervation to the base of the tongue, epiglottis, aryepiglottic folds, and the arytenoids, as well as motor innervation to the cricothyroid muscle. The recurrent ...