Exploring the Thyroid Gland: Structure, Blood Supply, and Function

THYROID GLAND GENERAL & BLOOD SUPPPLY

Bilobed, lobulated & 5cm long, extending to tracheal ring 6 •Shield shaped & lies on carotid sheath •Limited extension upwards by sternothyroid Can pass inferiorly into mediastinum Note relationship of branching of arteries to pretracheal fascia Upper pole Lateral lobe Lower pole Isthmus (on rings 2,3,4) Superior thyroid artery from external carotid Behind sympathetic chain Inferior thyroid artery from thyrocervical trunk (other banches are ascending cervical, transverse cervical & suprascapular) Thyroidea ima (3% from aorta) Note intimate relationship of branches of the inferior thyroid artery to the recurrent laryngeal nerve Function: Produces thyroxine and thyrocalcitonin External carotid a Superior thyroid a Internal jugular v Superior thyroid v -Middle thyroid v Inferior thyroid a Thyrocervical trunk Subclavian a Subclavian v Inferior thyroid v Lymph to deep cervical chain nodes Left brachiocephalic v Isthmus is firmly attached to rings 2,3,4 of trachea