Anatomy & Embryology: Thyroid Gland Flashcards
when does the thyroid gland start to develop
in the 4th week of embryogenesis
describe the origin and start of development of the thyroid gland
starts as midline thickening at the back of the tongue, and then stretches downwards
where does the thyroid gland migrate to
migrates inferiorly in front of the larynx, where it is in close proximity to the parathyroid glands
describe the thyroid gland at 7/8 weeks of embryogenesis
the 2 lobes are formed and joined by the isthmus, in front of the trachea and just below the larynx
describe what happens to the thyroglossal duct
usually duct loses contact with thyroid gland(except in 15% of people), where the pyramidal lobe of the thyroid remains
what happens if the thyroglossal duct fails to regress
thyroglossal duct cysts can form, anywhere along the migratory path of the thyroid gland
describe what happens at 12 weeks of embryogenesis at the thyroid gland
primitive follicles are visible as simple epithelium surrounding a central lumen, now able to trap iodide and and respond to TSH
what does the thyroid gland usually consist of
2 lateral lobes(right and left) and the isthmus(narrow connecting band between 2 lobes)
where do the lobes of the thyroid gland attach
to the lateral aspects of the thyroid and cricoid cartilages, and to the trachea
where does the isthmus usually sit
anterior to the 2nd and 3rd cartilages of the trachea
what is the prevalence of the pyramidal lobe of the thyroid gland
28-55%
where are the parathyroid glands located
located on posterior surfaces of the lateral lobes of the thyroid gland, 2 on each lobe one superior and one inferior
what is the parasympathetic innervation of the thyroid gland
vagus nerves
what is the sympathetic innervation of the thyroid gland
superior, middle and inferior ganglia of the sympathetic trunk
describe the blood supply to the thyroid gland
superior thyroid arteries, branch from external carotids
inferior thyroid arteries, branch from subclavian arteries
