| accessory thyroid | An isolated mass, or one of several such masses, of thyroid tissue, sometimes present in the side of the neck, or just above the hyoid bone (suprahyoid accessory thyroid gland), or even as low as the arch of the aorta. Synonym: glandula thyroidea accessoria, accessory thyroid, prehyoid gland, suprahyoid gland, thyroidea accessoria, thyroidea ima, Wolfler's gland. (05 Mar 2000) |
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| accessory thyroid gland | An isolated mass, or one of several such masses, of thyroid tissue, sometimes present in the side of the neck, or just above the hyoid bone (suprahyoid accessory thyroid gland), or even as low as the arch of the aorta. Synonym: glandula thyroidea accessoria, accessory thyroid, prehyoid gland, suprahyoid gland, thyroidea accessoria, thyroidea ima, Wolfler's gland. (05 Mar 2000) |
| anaplastic carcinoma of the thyroid | <oncology, tumour> An aggressive form and rare form of thyroid cancer that is one of the most rapidly growing and invasive types of thyroid cancer. It commonly occurs in people over 60 years of age and may cause obstruction of the trachea. The cause is unknown but exposure to radiation may be a factor. Thyroid function tests are usually normal. Hoarse voice, cough and coughing up blood are common symptoms. Examination may reveal nodules in the thyroid gland. Diagnosis is made via biopsy. Treatment is surgical with or without radiation therapy. (27 Sep 1997) |
| cancer, thyroid | Cancer of the gland in front of the neck that normally produces thyroid hormone which is important to the normal regulation of the metabolism of the body. There are four major types of cancer of the thyroid gland. Persons who received radiation to the head or neck in childhood should be examined by a doctor every 1 to 2 years. The most common symptom of thyroid cancer is a lump, or nodule, that can be felt in the neck. The only certain way to tell whether a thyroid lump is cancer is by examining the thyroid tissue obtained using a needle or surgery for biopsy. (12 Dec 1998) |
| receptors, thyroid hormone | Proteins, usually found in the nucleus, that specifically bind thyroid hormones and regulate DNA transcription. These proteins, termed c-erba, are activated by hormones and cause differentiation of erythroid progenitor cells which irreversibly lose proliferative potential. Thus c-erba proteins act as growth suppressors. The c-erba proteins are encoded by at least two genes, c-erba alpha and c-erba beta. Each of these has two isoforms. Mutations in the ligand-binding domain of the beta form causes thyroid hormone resistance syndrome. (12 Dec 1998) |
| giant cell carcinoma of thyroid gland | A rapidly progressive undifferentiated carcinoma observed in the thyroid gland, characterised by numerous, unusually large, anaplastic cells derived from glandular epithelium of the thyroid gland. (05 Mar 2000) |
| glandular branches of inferior thyroid artery | <anatomy, artery> Branches of inferior thyroid artery to thyroid and parathyroid glands, anastomosing with branches of superior thyroid artery. Synonym: rami glandulares arteriae thyroideae inferioris. (05 Mar 2000) |
| pharyngeal branch of inferior thyroid artery | <anatomy, artery> Distributed to laryngopharynx. Synonym: rami pharyngeales arteriae thyroideae inferioris. (05 Mar 2000) |
| middle thyroid vein | <anatomy, vein> It passes from the thyroid gland across the common carotid artery with the inferior thyroid arteries to empty into the internal jugular vein. Synonym: vena thyroidea media. (05 Mar 2000) |
| cornua of thyroid cartilage | See: inferior horn of thyroid cartilage, superior horn of thyroid cartilage. Cornu uteri, the portion of the uterus to which the intramural section of the uterine tube enters on either the right or left. Synonym: uterine horn, horn of uterus. (05 Mar 2000) |
| posterior branch of superior thyroid artery | <anatomy, artery> Branch of superior thyroid artery which descends to supply the apical portion of the ipsilateral lobe of the thyroid, continuing along the posterior border of the gland to anastomose with the inferior thyroid artery. Synonym: ramus posterior arteriae thyroideae superioris. (05 Mar 2000) |
| hormone, thyroid | Chemical substance made by the thyroid gland which is located in the front of the neck. The thyroid gland uses iodine to make thyroid hormones. The two most important thyroid hormones are thyroxine (t4) and triiodothyronine (t3). (12 Dec 1998) |
| hormone, thyroid stimulating | A hormone produced by the pituitary gland (at the base of the brain) that promotes the growth of the thyroid gland (in the neck) and stimulates it to produce its thyroid hormones. Normally, the rate of thyroid hormone production is controlled by the pituitary. When there are insufficient thyroid hormones in the body for normal functioning of the cells, the pituitary releases tsh. Tsh in turn stimulates the thyroid gland to produce more thyroid hormones. In contrast, when there is excessive amount of thyroid hormones, the pituitary gland stops producing tsh. The tsh level then falls and thyroid hormone production is reduced. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood. This phenomenon is analogous to a thermostat used for temperature regulation in a room: when the temperature rises, the thermostat shuts the heater off and the room temperature falls back to normal. High levels of thyroid hormones cause the tsh level to fall, resulting in no further stimulation of the thyroid gland. In hyperthyroidism, there are continuously elevated levels of the thyroid hormones. Tsh is also known as thyrotropin. (12 Dec 1998) |
| horns of thyroid cartilage | See: inferior horn of thyroid cartilage, superior horn of thyroid cartilage. (05 Mar 2000) |
| pyramidal lobe of thyroid gland | <anatomy> An inconstant narrow lobe of the thyroid gland that arises from the upper border of the isthmus and extends upward, sometimes as far as the hyoid bone; it marks the point of continuity with the thyroglossal duct. Synonym: lobus pyramidalis glandulae thyroideae, Lallouette's pyramid, Morgagni's appendix, pyramid of thyroid. (05 Mar 2000) |