Which nerve is responsible for the efferent innervation of the stylopharyngeus muscle?

The glossopharyngeal nerve plays a crucial role in the efferent innervation of the stylopharyngeus muscle, which is involved in the elevation of the pharynx during swallowing and speech. This muscle is unique in being the only one innervated by the glossopharyngeal nerve, distinguishing it from other pharyngeal muscles, which are generally innervated by the vagus nerve. The glossopharyngeal nerve not only provides motor function to the stylopharyngeus but also has important sensory functions, especially in taste from the posterior one-third of the tongue and sensory input from the oropharynx. This combination of roles underscores the importance of the glossopharyngeal nerve in both the motor control of pharyngeal muscles and sensory feedback during swallowing and phonation.