Gastric POCUS, 3-Part Episode

A lingual nerve block would abolish the gag reflex since the lingual nerve (mandibular division of CN V and CN IX) carries sensation for the tongue, vallecular, anterior epiglottis, posterior and lateral walls of the pharynx, and the tonsillar pillars as well as motor to the stylopharyngeus muscle. The gag reflex is blocked since the submucosa of the tongue base can no longer sense stimulation of the pressor receptors. A lingual nerve block is performed with the tongue pulled to the side and advancing a 25-gauge needle into the base of the palatoglossal fold and the palatoglossal arch approximately 0.25-0.5cm and injecting 2 ml of 2% lidocaine. Both the recurrent laryngeal nerve and the superior laryngeal nerve are branches of CN X. The external branch of the superior laryngeal nerve is responsible for adduction of the vocal cords by innervation of the cricothyroid muscle. The internal branch of the superior laryngeal nerve supplies sensory innervation to the base of the tongue, vallecula, epiglottis, aryepiglottic folds, arytenoids, and down to, but excluding, the vocal cords. A superior laryngeal nerve block may be done in order to block the internal branch prior to an awake intubation. This block is completed by advancing a 25-gauge needle past the cornu of the hyoid bone directed anterior-caudad towards the middle of the thyrohyoid ligament. At approximately 1-2 cm the needle will have passed through the ligament and will be in the space between the thyrohyoid membrane and the laryngeal mucosa where 2 ml of 2% lidocaine with 1:200,000 epinephrine should be injected. The responsibilities of the recurrent laryngeal nerve include motor innervation to the remaining intrinsic muscles of the larynx. A recurrent laryngeal nerve block can be performed to block sensation to the vocal cords and trachea and is beneficial to help prevent coughing. This nerve block can be performed by way of a transtracheal injection of 4 mls of 4% lidocaine on a 20 or 22-gauge needle passed through the cricothyroid membrane until easy aspiration of air. Sensory innervation of the nasopharynx comes from the maxillary division of the trigeminal nerve. Blocking this nerve would provide anesthesia to the nasopharynx for advancement of a nasal endotracheal tube, but would not abolish the gag reflex.