Editing Adenoid

{{Short description|Type of tonsil}}
{{For|"adenoid" meaning "glandular", "gland-like", or "lymphatic"|glandular|lymphatic}}
{{More citations needed|date=November 2007}}
{{Infobox lymph
| Name        = Adenoids
| Latin       = tonsilla pharyngea
| Image       = Gray994-adenoid.png
| Caption     = Location of the adenoid
| Image2      =
| Caption2    =
| Precursor   =
}}

In [[anatomy]], the '''pharyngeal tonsil''', also known as the '''nasopharyngeal tonsil''' or '''adenoid''', is the [[anatomical terms of location#Superior and inferior|superior]]-most of the [[tonsil]]s. It is a mass of [[Lymphatic tissues|lymphoid tissue]] located behind the [[nasal cavity]], in the roof and the posterior wall of the [[nasopharynx]],<ref name=":0">{{Cite book |url=https://www.worldcat.org/title/on1202943188 |title=Gray's anatomy: the anatomical basis of clinical practice |date=2021 |publisher=Elsevier |isbn=978-0-7020-7705-0 |editor-last=Standring |editor-first=Susan |edition=42nd |location=Amsterdam |pages=703 |oclc=on1202943188 |editor-last2=Gray |editor-first2=Henry}}</ref> where the [[human nose|nose]] blends into the [[throat]]. In [[child]]ren, it normally forms a soft mound in the roof and back wall of the nasopharynx, just above and behind the [[palatine uvula|uvula]].

The term ''adenoid'' is also used to represent [[adenoid hypertrophy]], the abnormal growth of the pharyngeal tonsils.<ref>{{Cite web|url=https://www.merriam-webster.com/dictionary/adenoid|title=Definition of ADENOID|website=www.merriam-webster.com|language=en|access-date=2018-05-05}}</ref>

==Structure==
The adenoid is a mass of [[Lymphatic tissues|lymphoid tissue]] located behind the nasal cavity, in the roof and the posterior wall of the [[nasopharynx]],<ref name=":0" /> where the nose blends into the throat. The adenoid, unlike the [[palatine tonsil]]s, has [[pseudostratified epithelium]].<ref>{{KansasHistology|lymphoid|lymph06}}</ref>  The adenoids are part of the so-called [[Waldeyer's tonsillar ring|Waldeyer ring]] of lymphoid tissue which also includes the palatine tonsils, the [[lingual tonsils]] and the [[tubal tonsils]].

=== Development ===
Adenoids develop from a subepithelial infiltration of [[lymphocytes]] after the 16th week of embryonic life. After birth, enlargement begins and continues until ages 5 to 7 years.

=== Function ===
Part of the immune system, adenoids trap and recognize pathogens such as bacteria and viruses. In response, the adenoid produces [[T cell]]s and [[B cell]]s to combat infection, contributing to the synthesis of IgA [[immunoglobulin]]s, assisting in the body's immunologic memory.<ref>{{cite journal |title=Anatomy, Head and Neck: Adenoids |url=https://www.ncbi.nlm.nih.gov/books/NBK538137/ |website=National Library of Medicine |date=2023 |pmid=30844164 |access-date=2 June 2023 |last1=Mnatsakanian |first1=A. |last2=Heil |first2=J. R. |last3=Sharma |first3=S. }}</ref>

=== Microbiome ===
Species of bacteria such as [[lactobacilli]], anaerobic streptococci, [[actinomycosis]], [[Fusobacterium]] species, and [[Nocardia]] are normally present by 6 months of age. Normal flora found in the adenoid consists of [[alpha-hemolytic streptococci]] and [[enterococci]], [[Corynebacterium]] species, [[coagulase-negative staphylococci]], [[Neisseria]] species, [[Haemophilus]] species, [[Micrococcus]] species, and [[Stomatococcus]] species.{{Citation needed|date=May 2018}}

==Clinical significance==

{{Main|Adenoid hypertrophy}}

=== Enlargement ===
[[File:Adenoid hypertrophy.jpg|thumb|258x258px|3D still showing adenoid hypertrophy.]]

An enlarged adenoid, or [[adenoid hypertrophy]], can become nearly the size of a [[ping pong ball]] and completely block airflow through the nasal passages. Even if the enlarged adenoid is not substantial enough to physically block the back of the nose, it can obstruct airflow enough so that breathing through the nose requires an uncomfortable amount of work, and inhalation occurs instead through an open mouth. The enlarged adenoid would also obstruct the nasal airway enough to affect the voice without actually stopping nasal airflow altogether.

Symptomatic enlargement between 18 and 24 months of age is not uncommon, meaning that [[snoring]], nasal airway obstruction and obstructed breathing may occur during sleep. However, this may be reasonably expected to decline when children reach school age, and progressive shrinkage may be expected thereafter.{{Citation needed|date=May 2018}}

===Adenoid facies===
Enlargement of the adenoid, especially in children, causes an atypical appearance of the face, often referred to as ''adenoid facies''.<ref>{{Cite journal|last=Jefferson|first=Yosh|date=2017-02-01|title=Mouth breathing: adverse effects on facial growth, health, academics, and behavior|journal=General Dentistry|volume=58|issue=1|pages=18–25; quiz 26–27, 79–80|issn=0363-6771|pmid=20129889}}</ref> Features of adenoid facies include [[mouth breathing]], an elongated face, prominent incisors, [[hypoplastic]] [[maxilla]], short upper lip, elevated nostrils, and a high arched palate.<ref>{{Cite web |url=https://radiopaedia.org/articles/adenoid-facies-2 |title=Adenoid facies |series=Radiology Reference Article |website=Radiopaedia.org |last=Wahba |first=Mohammed |access-date=2016-11-06}}</ref>

===Removal ===
Surgical removal of the adenoid is a procedure called [[adenoidectomy]]. Adenoid infection may cause symptoms such as excessive [[mucus]] production, which can be treated by its removal. Studies have shown that adenoid regrowth occurs in as many as 19% of the cases after removal.<ref>{{Cite journal|last1=Lesinskas|first1=Eugenijus|last2=Drigotas|first2=Martynas|date=2009-04-01|title=The incidence of adenoidal regrowth after adenoidectomy and its effect on persistent nasal symptoms|journal=European Archives of Oto-Rhino-Laryngology|volume=266|issue=4|pages=469–473|doi=10.1007/s00405-008-0892-5|issn=1434-4726|pmid=19093130|s2cid=31941117 }}</ref> Carried out through the mouth under a [[general anaesthetic]] (or less commonly a [[topical anesthetic|topical]]), adenoidectomy involves the adenoid being [[curette]]d, [[cauterization|cauterized]], [[Laser surgery|lasered]], or otherwise [[Ablation#Medicine|ablated]]. The adenoid is often removed along with the [[palatine tonsil]]s.<ref>{{cite web |title=Adenoids |url=https://medlineplus.gov/adenoids.html |publisher=MedlinePlus, US National Library of Medicine |access-date=23 July 2023 |date=13 September 2022}}</ref>

== See also ==
* [[Waldeyer's tonsillar ring]]

== References ==
{{Reflist}}

==External links==
* {{cite web|url=http://www.tk.de/rochelexikon/pics/s25420.000-1.html|title=Anatomy diagram: 25420.000-1|work= Roche Lexicon—Illustrated Navigator |publisher= Elsevier|archive-url=https://web.archive.org/web/20150226040726/http://www.tk.de/rochelexikon/pics/s25420.000-1.html|archive-date=2015-02-26}}
*[https://www.gutenberg.org/ebooks/27141 ''Adenoids: What They Are, How to Recognize Them, What to Do for Them'']
* [https://web.archive.org/web/20070106202643/http://bicmra.usuhs.mil/MRA/HSeries/H14/HTMLdocs/H14low.html Histology at usuhs.mil]
* [http://www.udel.edu/Biology/Wags/histopage/colorpage/cly/cly.htm Histology at udel.edu] ({{Webarchive|url=https://web.archive.org/web/20220921084036/http://www.udel.edu/Biology/Wags/histopage/colorpage/cly/cly.htm |date=2022-09-21 }})
* [https://web.archive.org/web/20070708115931/http://www.drtbalu.com/adenoid.html Adenoid] by Dr. T. Balasubramanian M.S. D.L.O. at drtbalu.com

{{Lymphatic organ anatomy}}
{{Nose anatomy}}
{{Authority control}}

[[Category:Lymphatics of the head and neck]]
[[Category:Otorhinolaryngology]]
[[Category:Pharynx]]
[[Category:Tonsil]]