What signals the contraction of muscles involved in swallowing?

The contraction of muscles involved in swallowing is primarily signaled by nerves from the brain. This process is controlled by the central nervous system, which coordinates the complex sequence of muscle contractions required for swallowing. The brain sends motor signals through specific cranial nerves, particularly the vagus nerve and glossopharyngeal nerve, to the muscles in the throat and esophagus, allowing for the proper movement of food from the mouth through the pharynx and into the esophagus.

Nerves from the brain play a crucial role in this reflex action, as they initiate and regulate the swallowing reflex by sending signals to the various muscle groups involved, ensuring that each phase of swallowing occurs in the correct sequence. This coordination is vital for effective swallowing and preventing aspiration, where food or liquid may enter the airway instead of the esophagus.