Certified Neuroscience Registered Nurse (CNRN) Practice Exam

What nerve innervates the esophagus at the lower esophageal sphincter to help prevent acid reflux?

1. Vagus nerve

2. Sciatic nerve

3. Phrenic nerve

4. Trigeminal nerve

The correct answer is: Vagus nerve

The vagus nerve is crucial for the innervation of the esophagus, particularly at the lower esophageal sphincter (LES). This nerve is a key component of the parasympathetic nervous system and plays a significant role in controlling various functions of the digestive system. It helps regulate the motility of the esophagus, facilitating the movement of food towards the stomach and also in maintaining the function of the lower esophageal sphincter. The role of the vagus nerve in preventing acid reflux is vital because it influences the contraction and relaxation of the LES. If the sphincter is not functioning properly, it can lead to the backflow of stomach contents, resulting in gastroesophageal reflux disease (GERD). By reinforcing the tone and function of the LES, the vagus nerve helps prevent this unwanted reflux of acid. Other nerves listed, such as the sciatic, phrenic, and trigeminal nerves, do not play a direct role in the innervation of the esophagus or the regulation of the lower esophageal sphincter. The sciatic nerve mainly functions in the lower limb, the phrenic nerve is primarily involved in diaphragm movement and respiration, and the trigeminal nerve is responsible for facial sensation and