So the pharynx is the passageway that connects the nasal and the oral cavity to our windpipe, our larynx and the trachea as well as to our esophagus. It allows not only the movement of air into and out of the lungs but it also allows the movement of our food bowls into our esophagus. Now, in order to actually prevent the movement of the food into our windpipe, a cartilage in this flap called the epiglottis forms a protective barrier that keeps the food out of the larynx. So as the tongue and other voluntary muscles found in the mouth initiate the process of swallowing wing, this reflex creates the movement of that epiglottis and the epiglottis basically shuts close and that prevents the movement of our bolus into our air passageway into the larynx. Now, we have a special type of circular muscle that basically connects, that separates our esophagus as well as the pharynx and this is known as our esophageal sphincter. And this esophageal sphincter relaxes and opens and allows the movement of that bolus into our esophagus.