Editing Thyroid (section)

===Features===
[[File:Illu08 thyroid.jpg|thumb| The thyroid gland surrounds the [[cricoid cartilage|cricoid]] and [[trachea|tracheal cartilages]] and consists of two lobes. This image shows a variant thyroid with a pyramidal lobe emerging from the middle of the thyroid.|alt=Image showing the thyroid gland surrounding the cricoid cartilage]]

The thyroid gland is a butterfly-shaped organ composed of two lobes, left and right, connected by a narrow tissue band, called an "isthmus".{{sfn|Gray's Anatomy|2008|pp=462–4}} It weighs 25 grams in adults, with each lobe being about 5&nbsp;cm long, 3&nbsp;cm wide, and 2&nbsp;cm thick and the isthmus about 1.25&nbsp;cm in height and width.{{sfn|Gray's Anatomy|2008|pp=462–4}} The gland is usually larger in women than in men, and increases in size during pregnancy.{{sfn|Gray's Anatomy|2008|pp=462–4}}{{sfn|Elsevier's|2007|p=342}}

The thyroid is near the front of the neck, lying against and around the front of the [[larynx]] and [[trachea]].{{sfn|Gray's Anatomy|2008|pp=462–4}} The [[thyroid cartilage]] and [[cricoid cartilage]] lie just above the gland, below the [[Adam's apple]]. The isthmus extends from the second to third [[rings of the trachea]], with the uppermost part of the lobes extending to the thyroid cartilage and the lowermost around the fourth to sixth tracheal rings.{{sfn|Elsevier's|2007|pp=342–3}} The [[infrahyoid muscles]] lie in front of the gland and the [[sternocleidomastoid muscle]] to the side.<ref name="isbn0-443-07168-3">{{cite book | last1 = Ellis | first1 = Harold | first2 = Susan | last2 = Standring | last3 = Gray | first3 = Henry David | name-list-style = vanc |title=Gray's anatomy: the anatomical basis of clinical practice |publisher=Elsevier Churchill Livingstone |location=St. Louis, Mo |year=2005 |pages=[https://archive.org/details/graysanatomyanat0000unse/page/538 538–539] |isbn=978-0-443-07168-3 |url=https://archive.org/details/graysanatomyanat0000unse/page/538 }}</ref> Behind the outer wings of the thyroid lie the two [[carotid artery|carotid arteries]]. The trachea, larynx, lower pharynx and esophagus all lie behind the thyroid.{{sfn|Elsevier's|2007|p=342}} In this region, the [[recurrent laryngeal nerve]]<ref name="Netter">{{cite book|last1=Netter|first1=Frank H. | name-list-style = vanc |title=Atlas of Human Anatomy Including Student Consult Interactive Ancillaries and Guides.|date=2014|publisher=W B Saunders Co|location=Philadelphia, Penn.|isbn=978-1-4557-0418-7|page=27|edition=6th}}</ref> and the inferior thyroid artery pass next to or in the ligament.<ref name=PAGE2009>{{cite journal | vauthors = Page C, Cuvelier P, Biet A, Boute P, Laude M, Strunski V | title = Thyroid tubercle of Zuckerkandl: anatomical and surgical experience from 79 thyroidectomies | journal = The Journal of Laryngology and Otology | volume = 123 | issue = 7 | pages = 768–71 | date = July 2009 | pmid = 19000342 | doi = 10.1017/s0022215108004003 | s2cid = 22063700 }}</ref> Typically, four [[parathyroid gland]]s, two on each side, lie on each side between the two layers of the thyroid capsule, at the back of the thyroid lobes.{{sfn|Gray's Anatomy|2008|pp=462–4}}

The thyroid gland is covered by a thin fibrous capsule,{{sfn|Gray's Anatomy|2008|pp=462–4}} which has an inner and an outer layer. The inner layer extrudes into the gland and forms the [[septum|septa]] that divide the thyroid tissue into microscopic lobules.{{sfn|Gray's Anatomy|2008|pp=462–4}} The outer layer is continuous with the [[pretracheal fascia]], attaching the gland to the cricoid and thyroid cartilages{{sfn|Elsevier's|2007|p=342}} via a thickening of the fascia to form the posterior [[suspensory ligament of thyroid gland]], also known as Berry's ligament.{{sfn|Elsevier's|2007|p=342}} This causes the thyroid to move up and down with the movement of these cartilages when swallowing occurs.{{sfn|Elsevier's|2007|p=342}}