Tonsil


 * For the structure in the cerebellum, see cerebellar tonsil.

The tonsils are areas of lymphoid tissue on either side of the throat. An infection of the tonsils is called tonsillitis. Most commonly, the term "tonsils" refers to the palatine tonsils that can be seen in the back of the throat.

As with other organs of the lymphatic system, the tonsils act as part of the immune system to help protect against infection. In particular, they are believed to be involved in helping fight off pharyngeal and upper respiratory tract infections.

Tonsils in humans include, from superior to inferior:

Together this set of lymphatic tissue is known as Waldeyer's tonsillar ring.

Tonsils tend to reach their largest size near puberty, and they gradually undergo atrophy thereafter. However, they are largest relative to the diameter of the throat in young children, and tonsillectomy (surgical removal of tonsils) may be indicated if they are obstructing the airway or interfering with swallowing. Also, when tonsils become overly enlarged or inflamed they may need to be surgically removed.