Thyroid Gland
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Original Editor - Niha Mulla
Top Contributors - Niha Mulla, Lucinda hampton, Kim Jackson and Carina Therese Magtibay
Introduction[edit | edit source]
Thyroid gland is a part of human endocrine system. Thyroid gland works together with the nervous system and the immune system to regulate the body metabolism by secreting hormone and releasing it into the blood stream . [1]
Anatomy[edit | edit source]
Thyroid gland is a butterfly shaped organ and is situated at the front of the neck in the lower part of the throat and consists of two connected lobes on either side of the wind pipe. Lower end of the lobes is connected by thyroid isthmus which is a thin band of connective tissue. [1][2] [3]
It weighs 25 grams in adults, with each lobe being about 5 cm long, 3 cm wide, and 2 cm thick. The thyroid gland is comparatively larger in women as compared to men and also increases in size during pregnancy. The infrahyoid muscles lie in front of the gland and the sternocleidomastoid muscle to the side. Behind the outer wings of the thyroid lie the two carotid arteries whereas the trachea, larynx, lower pharynx and esophagus all lie behind the thyroid. Four parathyroid glands, two on each side, lie on each side between the two layers of the thyroid capsule, at the back of the thyroid lobes.[2]
Blood supply of thyroid gland[edit | edit source]
The thyroid gland is supplied with arterial blood from:[2]
- The superior thyroid artery - a branch of the external carotid artery.
- The inferior thyroid artery - a branch of the thyrocervical trunk.
- And sometimes, by an anatomical variant the thyroid ima artery which has a variable origin.
- The superior thyroid artery splits into anterior and posterior branches supplying the thyroid, and the inferior thyroid artery splits into superior and inferior branches.
The venous blood is drained via superior and middle thyroid veins, which drain to the internal jugular vein and via the inferior thyroid veins. Both arteries and veins form a plexus between the two layers of the capsule of the thyroid gland.[2]
Nerve supply of thyroid gland[edit | edit source]
The gland receives sympathetic nerve supply from the superior, middle and inferior cervical ganglion of the sympathetic trunk whereas the gland receives parasympathetic nerve supply from the superior laryngeal nerve and the recurrent laryngeal nerve.[2]
Lymphatic drainage[edit | edit source]
Lymphatic drainage frequently passes through:[2]
- Pre-laryngeal lymph nodes which is located just above the isthmus
- Pre-tracheal and
- Paratracheal lymph nodes.
Function of thyroid gland[edit | edit source]
Clinical significance[edit | edit source]
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References[edit | edit source]
- ↑ 1.0 1.1 The thyroid gland. Government of Western Australia, Department of Health. Available from https://www.healthywa.wa.gov.au/Articles/S_T/The-thyroid-gland
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Thyroid. Wikipedia. Wikimedia Foundation; Available from: https://en.wikipedia.org/wiki/Thyroid
- ↑ Hoffman M. The thyroid (human anatomy): Picture, function, definition, location in the body, and more. WebMD. WebMD; 2021. Available from: https://www.webmd.com/women/picture-of-the-thyroid
