Certified Registered Nurse Anesthetist (CRNA) Practice Exam

Which approaches are useful for blocking the internal branch of the superior laryngeal nerve?

1. Direct laryngeal injection only

2. Topical anesthesia of the pyriform fossae, inhalation of nebulized local anesthetic, nerve block through the thyroid membrane

3. Only inhalation of general anesthetic

4. Nerve block via the cricothyroid membrane

The correct answer is: Topical anesthesia of the pyriform fossae, inhalation of nebulized local anesthetic, nerve block through the thyroid membrane

The internal branch of the superior laryngeal nerve is responsible for providing sensory innervation to the laryngeal mucosa above the vocal cords. Blocking this nerve can be advantageous in procedures involving the airway, particularly to prevent reflex coughing and facilitate intubation. The correct approach involves multiple modalities for effective blocking of the internal branch. Topical anesthesia of the pyriform fossae, for example, allows local anesthetic to diffuse and numb the area innervated by the nerve. Inhalation of nebulized local anesthetic is another effective method, enabling widespread distribution of the anesthetic to sensitive areas of the airway. Additionally, performing a nerve block through the thyroid membrane allows for direct targeting of the superior laryngeal nerve, enhancing the effectiveness of the anesthetic blockade. In contrast, other approaches may not provide as comprehensive or effective a result. Direct laryngeal injection could be limited in scope and access. Relying solely on inhalation of general anesthetic does not specifically target the sensory branches of the nerve and would not offer the localized anesthesia needed at the level of the larynx. Nerve block via the cricothyroid membrane is not as suitable for targeting the internal branch, as it may not reach