Which nerve is responsible for mediating information from the carotid bodies?

The glossopharyngeal nerve is primarily responsible for mediating sensory information from the carotid bodies, which are specialized chemoreceptors located at the bifurcation of the common carotid arteries. These chemoreceptors play a crucial role in detecting changes in blood chemistry, specifically levels of oxygen, carbon dioxide, and pH, which are essential for regulating respiratory and cardiovascular functions.

The information gathered by the carotid bodies is transmitted through the glossopharyngeal nerve to the brainstem centers that regulate autonomic responses, such as adjusting breathing rates and heart function based on the body's metabolic needs. This neural pathway is vital for maintaining homeostasis in response to fluctuating blood gas levels.

In contrast, other nerves such as the vagus nerve, while also involved in autonomic functions, do not carry sensory information from the carotid bodies. The accessory nerve primarily innervates certain muscles of the neck and shoulder and does not have a sensory function related to blood chemistry. The trigeminal nerve is mainly responsible for sensory information from the face and does not involve chemoreception in the carotid region. Thus, the glossopharyngeal nerve is specifically linked to the function of the carotid bodies, making it the correct answer.