adenoids [ad′'n oidz΄, ad′noidz΄]
growths of lymphoid tissue in the upper part of the throat, behind the nose: they can swell up, esp. during childhood, obstruct breathing and speaking, and cause chronic ear infections

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or pharyngeal tonsils

Mass of lymphoid tissue, similar to the (palatine) tonsils, on the back wall of the nasal pharynx.

If the adenoids become infected in childhood, their inflammation can obstruct nasal breathing and sinus drainage (promoting sinusitis) and block the eustachian tubes that connect to the middle ear (setting the stage for otitis). Surgical removal of enlarged or infected adenoids is frequently recommended.

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▪ human anatomy
also called  Pharyngeal Tonsils 

      a mass of lymphatic (lymphatic system) tissue, similar to the (palatine) tonsils, that is attached to the back wall of the nasal pharynx (i.e., the upper part of the throat opening into the nasal cavity proper). An individual fold of such nasopharyngeal lymphatic tissue is called an adenoid.

      The surface layer of the adenoids consists of ciliated epithelial cells covered by a thin film of mucus. The cilia (cilium), which are microscopic hairlike projections from the surface cells, move constantly in a wavelike manner and propel the blanket of mucus down to the pharynx proper. From that point the mucus is caught by the swallowing action of the pharyngeal (throat) muscles and is sent down to the stomach. The adenoids also contain glands that secrete mucus to replenish the surface film. The function of the adenoids is protective. The moving film of mucus tends to carry infectious agents and dust particles inhaled through the nose down to the pharynx, where the epithelium is more resistant. Immune substances, or antibodies, are thought to be formed within the lymphatic tissue, which, combined with phagocytic action, tends to arrest and absorb infectious agents.

      The adenoids usually enlarge in early childhood (childhood disease and disorder). Infections in childhood can cause swelling and inflammation of the adenoids and may permanently enlarge them. Large adenoids obstruct breathing through the nose and interfere with sinus drainage, thus predisposing the person to infections of the sinuses. Chronic respiratory (respiratory disease) obstruction and the resultant mouth breathing produce a characteristic vacant facial expression on a person with enlarged adenoids. The adenoids' infection and enlargement also predispose to blockage of the eustachian tubes (eustachian tube) (the passages extending from the nasal pharynx to the middle ear) and thus to middle-ear infections. Surgical removal, often in conjunction with the removal of the tonsils (tonsillectomy), is frequently recommended for children with enlarged or infected adenoids. Adenoids normally decrease in size after childhood. See also tonsil.

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Universalium. 2010.