The palatine uvula is a small, bell-shaped organ that hangs down in the back of the mouth and blocks the interior nasal passages while swallowing. The uvula has other functions, such as secreting a small amount of saliva, but preventing nasal regurgitation is one of its most important roles.
The uvula is a small process of the soft palate that occupies a spot near the top of the throat between the tonsils. It contains a small muscle that can expand and contract to change the geometry of the uvula or to press it firmly against the back of the throat.
The uvula is usually static, moving only as the throat expands as when swallowing. As a normal part of the swallowing process, the soft palate recedes from the base of the tongue and opens a clear path to the esophagus. The uvula is lifted by this motion and comes to rest against the nasopharyngeal opening, the passage leading from the throat to the nose. By blocking this opening, the uvula prevents food and liquids from surging back up into the nose.
The uvula also plays a role in speech. People with cleft or absent uvulas often have nasal voices, as air is free to move through the nose with speech.