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Thyroid anatomy - Coggle Diagram
Thyroid anatomy
Surgical anatomy
2 lobes connected with isthmus in midline
Extension
Inf.
Isthmus
gland
Sup.
Weight (20-25 gm)
Relations
Superficially
Posteromedially
Medially
Superiorly
posterolaterally
Pretracheal fascia
Arteries
Inf. thyroid a.
Thyroid ima a.
Sup. thyroid a.
Esophageal a.
Veins
Middle thyroid v.
Inf, thyroid v.
Sup. thyroid v.
Lymphatics
Supscapular plexus
Some lymphatics
Emberyological
appears by 3rd week of life
Proliferation of epithelial cells in the floor of developing pharynx (thyroglossal duct)
Thyroid primordium descends and units with ultimobranchial body ( from 4th pharyngeal pouch)
Parafollicular C cells are drived from neural crest >> via ultimobranchial body >> to thyroid gland
Thyroglossal duct obliterate after the thyroid reach its position in the lower neck
Physiological
Brownish red highly vascular endocrine gland
Thyroid lobule is the functional unit (20-40 follicles lined by cubical epith.)
Colloid is stored in resting follicles (contain thryroglobulin)
Thyroid hormone synthesis
Iodide trapping from blood
Oxidation of iodide to iodine
Iodine + tyrozine >>>> mono & di iodotyrozine (tyrozinase)
T3 & T4 formation then binding with thyroglobulin and stored
Release into circulation ( free & total forms)
Not used mono & di are deiodinated by dehalogenase the iodine reused
Hypothalamic - Pitutary axis
Synthesis and liberation is controlled by TSH from ant. pitutary (feed back mechanism)
TRH from hypothalamus also stimulate production
Applied anatomy