[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Head and neck: pharyngeal arches](https://durgical.com/en/embryology/#a-head_neck) › Thyroid gland: from the foramen cecum to the neck [Embryology](https://durgical.com/en/embryology/) · [Head and neck: pharyngeal arches](https://durgical.com/en/embryology/#a-head_neck) # Thyroid gland: from the foramen cecum to the neck - Embryonic structure The thyroid starts at the base of the tongue and travels down the neck to sit in front of the trachea. On the way it can leave cysts or misplaced tissue. Updated 2026-11-01 **See it in 3D:** [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/) · [Tongue](https://durgical.com/en/anatomy/tongue/) · [Hyoid bone](https://durgical.com/en/anatomy/hyoid-bone/) · [Thyroid cartilage](https://durgical.com/en/anatomy/thyroid-cartilage/) · [Cricoid cartilage](https://durgical.com/en/anatomy/cricoid-cartilage/) ## Key points - Origin: floor-of-pharynx endoderm, at the foramen cecum. - Descends tied to the tongue by the thyroglossal duct. - Reaches its final site around week 7. - C cells: from the ultimobranchial body (4th pouch). - Leftovers of the path: thyroglossal cyst, lingual thyroid, pyramidal lobe. ## What it is The thyroid is the first endocrine gland to appear in the embryo: it buds from the floor of the pharynx, at the spot that later becomes the foramen cecum of the tongue. It descends in front of the hyoid and laryngeal cartilages, tied to the tongue by the thyroglossal duct, and reaches the front of the trachea around week 7. Its descent explains the thyroglossal duct cyst, lingual thyroid and pyramidal lobe. ## Key facts - The fetal thyroid works from the end of the first trimester; before that the fetus relies on maternal hormone. - Ectopic thyroid tissue can remain anywhere along the path; the commonest site is the base of the tongue. - The thyroid primordium depends on transcription factors such as NKX2-1, PAX8 and FOXE1. ## Structure - Follicular cells: floor-of-pharynx endoderm; they make thyroxine and triiodothyronine. - Parafollicular (C) cells: arrive with the ultimobranchial body of the 4th pouch; they make calcitonin. - Midline isthmus and two lateral lobes; sometimes a pyramidal lobe, a remnant of the lower end of the duct. ## What it becomes - Adult thyroid in front of the trachea, below the cricoid cartilage. - Foramen cecum at the apex of the terminal sulcus of the tongue. - Pyramidal lobe (in some people). ## Step by step - Weeks 3–4: a thickening of floor-of-pharynx endoderm, between the tuberculum impar and the copula, forms the thyroid primordium. - The primordium becomes a bilobed diverticulum that descends in front of the pharyngeal gut. - During descent it stays tied to the tongue by the thyroglossal duct. - It passes in front of the hyoid and the laryngeal cartilages. - Week 7: it reaches the front of the upper tracheal rings, with an isthmus and two lobes. - The thyroglossal duct disappears; its origin stays marked by the foramen cecum. - Towards the end of the third month follicles with colloid appear and the gland starts to work. ## Markers - NKX2-1 - PAX8 - FOXE1 - HHEX ## Clinical notes - Thyroglossal duct cyst: a midline mass near the hyoid that rises on swallowing or sticking out the tongue. - Lingual thyroid: a mass at the base of the tongue; it may be the patient's only thyroid tissue. - Thyroid dysgenesis (agenesis, ectopy, hypoplasia) is the commonest cause of congenital hypothyroidism, picked up by newborn TSH screening. - Medullary carcinoma arises from C cells, not follicular cells. ## Memory aid The thyroid is a gland that 'left home': it walked out of the tongue's front door (foramen cecum) and down to the trachea, leaving a trail in the midline. ## Test yourself Think of the answer, then tap the question to see it. ## What marks the thyroid's site of origin in the adult? The foramen cecum, at the apex of the terminal sulcus of the tongue. ## What connects the thyroid to the tongue during its descent? The thyroglossal duct, which later disappears. ## What is the commonest cause of congenital hypothyroidism? Thyroid dysgenesis: agenesis, ectopy (especially lingual thyroid) or hypoplasia of the gland. ## Where do the calcitonin-producing cells come from? From the ultimobranchial body, a fourth-pouch derivative that is incorporated into the thyroid. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/embryology/thyroid-gland-from-the-foramen-cecum-to-the-neck/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/) - [Tongue](https://durgical.com/en/anatomy/tongue/) - [Hyoid bone](https://durgical.com/en/anatomy/hyoid-bone/) - [Thyroid cartilage](https://durgical.com/en/anatomy/thyroid-cartilage/) - [Cricoid cartilage](https://durgical.com/en/anatomy/cricoid-cartilage/) ## Related - [Thyroglossal duct cyst and ectopic thyroid](https://durgical.com/en/embryology/thyroglossal-duct-cyst-and-ectopic-thyroid/) - [Tongue: development and innervation](https://durgical.com/en/embryology/tongue-development-and-innervation/) - [Pharyngeal pouches: tonsil, thymus, parathyroids and C cells](https://durgical.com/en/embryology/pharyngeal-pouches-tonsil-thymus-parathyroids-and-c-cells/) - [Foregut: esophagus, stomach rotation and duodenum](https://durgical.com/en/embryology/foregut-esophagus-stomach-rotation-and-duodenum/) - [The pharyngeal apparatus: arches, pouches, clefts and membranes](https://durgical.com/en/embryology/the-pharyngeal-apparatus-arches-pouches-clefts-and-membranes/) ## Related conditions - [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/) - [Goitre](https://durgical.com/en/conditions/goitre/) - [Thyroid cancer (papillary)](https://durgical.com/en/conditions/thyroid-cancer/) - [Thyroid nodule](https://durgical.com/en/conditions/thyroid-nodule/) [← All of embryology](https://durgical.com/en/embryology/) Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given. Sources: [Thyroglossal Duct Cyst - StatPearls - NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK519057/) (StatPearls Publishing (NCBI Bookshelf), 2025); [Embryology, Parathyroid - StatPearls - NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK554580/) (StatPearls Publishing (NCBI Bookshelf), 2023); Langman's Medical Embryology, 13th ed., ch. 17: Head and Neck (Wolters Kluwer, 2015). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/thyroid-gland-from-the-foramen-cecum-to-the-neck/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/thyroid-gland-from-the-foramen-cecum-to-the-neck/