Why is swallowing involuntary

This reflexive phase of swallowing should not be confused with SS. There are differences in the role of the corticobulbar input between VS and SS. Abstract This review examines the evidence regarding the clinical and neurophysiological differences between voluntary and spontaneous swallows. Part of swallowing is voluntary. This means you are aware of controlling the action.

However, much of swallowing is involuntary. The structures involved with the process of swallowing include the tongue, teeth, epiglottis, and esophagus. The teeth are used to grind and chop up food into tiny pieces, while the glands in the mouth moisten the food with saliva.

In the first stage of swallowing, the tongue pushes the food into the throat. In the second stage of swallowing, an important small flap of tissue called the epiglottis, folds over the voice box larynx at the entrance to the windpipe trachea , preventing food from going down the wrong way.

In the final stage, the esophagus contracts and moves food toward the stomach. Problems at any point in the swallowing process including chewing, moving food to the back of the mouth, or moving it to the stomach can result in painful swallowing.

Devault KR. Symptoms of esophageal disease. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. Philadelphia, PA: Elsevier Saunders; chap Nussenbaum B, Bradford CR. Pharyngitis in adults.

As the food bolus reaches the pharynx, special sensory nerves activate the involuntary phase of swallowing. The swallowing reflex, which is mediated by the swallowing center in the medulla the lower part of the brainstem , causes the food to be further pushed back into the pharynx and the esophagus food pipe by rhythmic and involuntary contractions of several muscles in the back of the mouth, pharynx, and esophagus.

Because the mouth and throat serve as an entryway for both food and air, the mouth provides a route for air to get into the windpipe and into the lungs, and it also provides a route for food to get into the esophagus and into the stomach. A critical part of the pharyngeal phase is the involuntary closure of the larynx by the epiglottis and vocal cords, and the temporary inhibition of breathing. The closure of the larynx by the epiglottis protects the lungs from injury, as food and other particles that enter into the lungs can lead to severe infections and irritation of the lung tissue.

Lung infections caused by problems with the pharyngeal phase of the swallowing reflex are commonly known as aspiration pneumonia.

As food leaves the pharynx, it enters the esophagus, a tube-like muscular structure that leads food into the stomach due to its powerful coordinated muscular contractions. The passage of food through the esophagus during this phase requires the coordinated action of the vagus nerve , the glossopharyngeal nerve, and nerve fibers from the sympathetic nervous system.

The esophagus has two important muscles that open and close reflexively as the food bolus is brought down during swallowing. These muscles, called sphincters, allow the food bolus to flow in a forward direction while preventing it from going in the wrong direction regurgitation.

Both esophageal sphincters, first the upper, and then the lower, open in response to the pressure of the food bolus and close after the food bolus passes. The upper esophageal sphincter prevents food or saliva from being regurgitated back into the mouth, while the lower esophageal sphincter ensures that food remains in the stomach, preventing regurgitation back into the esophagus.

In doing so, the esophageal sphincters serve as a physical barrier to regurgitated food. In general, healthy people can swallow with very little deliberate thought and effort. If the nervous system is disrupted due to a stroke or another disease, then problems with swallowing can occur. Swallowing difficulties are referred to as dysphagia. Dysphagia can lead to problems such as choking, lack of appetite and weight loss, and aspiration pneumonia.

If you have experienced a stroke or another neurological illness, you may undergo a swallowing evaluation to determine whether you have dysphagia. If you have signs of dysphagia, you will need to have speech and swallow therapy so that your swallowing muscles can have the chance to improve as much as possible. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life.

Updated March 6, Your Privacy Rights.