|Lymph: Waldeyer's tonsillar ring
|Regional lymphatics. Waldeyer ring labeled at center top.
||anulus lymphoideus pharyngis
Waldeyer's tonsillar ring (also pharyngeal lymphoid ring or Waldeyer's lymphatic ring) is an anatomical term collectively describing the annular arrangement of lymphoid tissue in the pharynx. Waldeyer's ring circumscribes the naso- and oropharynx, with some of its tonsillar tissue located above and some below the soft palate (and to the back of the oral cavity).
Waldeyer's ring was named after the nineteenth century German anatomist Heinrich Wilhelm Gottfried von Waldeyer-Hartz.
The ring consists of the (from superior to inferior):
There also normally is a good amount of mucosa-associated lymphoid tissue (MALT) present between all these tonsils (intertonsillar) around the ring, and more of this lymphoid tissue can variably be found more or less throughout at least the naso- and oropharynx.
Some animals, but not humans, have one or two additional tonsils:
- Soft palate tonsil
- Paraepiglottic tonsil
- ^ Some authors speak of two pharyngeal tonsils/two adenoids. These authors simply look at the left and right halves of the pharyngeal tonsil as two tonsils.
- ^ which is more common in children and can obstruct respiration
- ^ Many authors also speak of lingual tonsils (in the plural), because this accumulation of lymphoid tissue consists of a number of little prominences – many smaller rounded masses. Whether to collectively call all these a single tonsil or separate tonsils is to an extent an arbitrary decision.