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Waldeyer ring describes a circular structure of lymphoid tissue located in the nasopharynx and the oropharynx. It is formed by the two palatine tonsils, pharyngeal tonsils or adenoids, tubal or Gelach tonsils surrounding eustachian tube opening and lingual tonsils. The lymphoid tissue of Waldeyer tonsillar ring contains B-cell lymphocytes, T-cell lymphocytes, and a few mature plasma cells. This tissue is primarily involved in secretory immunity and regulates immunoglobulin production.
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The cells are organized in lymphoid follicles similar to lymph nodes, but have specialized endothelium-covered channels that facilitate antigen uptake directly into the tissue. The independence of this system from lymphatic drainage is a unique advantage for antigen acquisition. The location of Waldeyer tonsillar ring and its design allow direct exposure of the immunologically active cells to foreign antigens entering the upper aerodigestive tract, which maximizes immunologic memory. These tissues are most active from the ages of 4–10 and tend to involute after puberty. After their involution, the secretory immune function of these tissues remains, but at a lower level.
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The palatine tonsils are the largest component of the Waldeyer ring and are found in the lateral walls of the oropharynx. The tonsils are located within a tonsillar fossa formed by three pharyngeal muscles. The palatoglossus muscle forms the anterior tonsillar pillar, the palatopharyngeal muscle forms the posterior tonsillar pillar, and the base of the tonsillar fossa is formed by the pharyngeal constrictors, primarily the superior constrictor. The fibrous capsule of a tonsil is attached to the fascia of the pharyngeal muscles. The potential space between the tonsil and the pharyngeal muscles is a usual site of a peritonsillar abscess.
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The glossopharyngeal nerve lies deep to the superior pharyngeal constrictor and supplies sensation to the tonsil through the tonsillar branch. The tympanic branch of glossopharyngeal nerve is responsible for a referred otalgia that is commonly present with tonsillar inflammation or following tonsillar surgery. The descending branches of the lesser palatine nerve are another sensory supply to the tonsil. The arterial blood supply is primarily based at the inferior pole, and the tonsillar branch of the dorsal lingual artery, the ascending branch of the palatine artery, and the tonsillar branch of the facial artery enter at this site. The superior pole receives its blood supply from the ascending pharyngeal artery and from the lesser palatine artery. Venous drainage occurs through a venous peritonsillar plexus that drains into the lingual and pharyngeal veins and feeds into the internal jugular vein. Lymphatic drainage is usually to the tonsillar lymph node behind the angle of the mandible, or to other jugulodigastric lymph nodes.
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The tonsillar lymphoid tissue forms deep crypts that are lined with stratified antigen-processing squamous epithelium. These crypts maximize the exposure of tissue to surface antigens. They can also harbor debris and bacteria and become a source for infection, halitosis, and tonsilloliths.
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The adenoids or pharyngeal tonsils and the lingual tonsils are not as well ...