Waldeyer's tonsillar ring (or pharyngeal lymphoid ring) is an anatomical term describing the lymphoid tissue

Lymphatic system

The lymphoid system is the part of the immune system comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally toward the heart. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated...

 ring located in the pharynx

Pharynx

The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...

 and to the back of the oral cavity.

It was named after the nineteenth century German

Germans

The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

 anatomist

Anatomy

Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...

 Heinrich Wilhelm Gottfried von Waldeyer-Hartz

Heinrich Wilhelm Gottfried von Waldeyer-Hartz

Heinrich Wilhelm Gottfried von Waldeyer-Hartz was a German anatomist, famous for consolidating the neuron theory of organization of the nervous system and for naming the chromosome...

.

The ring consists of (from superior to inferior):

• Pharyngeal tonsil (also known as 'adenoids' when infected)
• Tubal tonsil
  Tubal tonsil
  The tubal tonsil is one of the four main tonsil groups which include the Palatine tonsil, the Lingual tonsil, the Pharyngeal tonsil, and the Tubal tonsil....
  
   (where the Eustachian tube opens in the nasopharynx)
• Palatine tonsils (commonly called "the tonsils" in the vernacular, less commonly termed "faucial tonsils")
• Lingual tonsils
  Lingual tonsils
  The lingual tonsils are rounded masses of lymphatic tissue that cover the posterior region of the tongue.They are located on the dorsal surface at the base of the tongue. Their lymphatic tissue are dense and nodular, their surface is covered with stratified squamous epithelium which invaginates as...
  
  

There also normally is a good amount of mucosa-associated lymphoid tissue (MALT

Mucosa-associated lymphoid tissue

The mucosa-associated lymphoid tissue is the diffusion system of small concentrations of lymphoid tissue found in various sites of the body, such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin.MALT is populated by lymphocytes such as T cells and B cells, as...

) present between these tonsils (intertonsillar) around the ring, and more of this lymphoid tissue can variably be found more or less throughout at least the naso-

Nasopharynx

The nasopharynx is the uppermost part of the pharynx. It extends from the base of the skull to the upper surface of the soft palate; it differs from the oral and laryngeal parts of the pharynx in that its cavity always remains patent .-Lateral:On its lateral wall is the pharyngeal ostium of the...

 and oropharynx

Oropharynx

The Oropharynx reaches from the Uvula to the level of the hyoid bone.It opens anteriorly, through the isthmus faucium, into the mouth, while in its lateral wall, between the two palatine arches, is the palatine tonsil....

.

Some animals, but not humans, have one or two additional tonsils:

• Soft palate tonsil
• Paraepiglottic tonsil