| 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) |
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| horns of thyroid cartilage | See: inferior horn of thyroid cartilage, superior horn of thyroid cartilage. (05 Mar 2000) |
| hot thyroid nodule | <radiology> Almost always hyperfunctioning adenoma, vast majority benign, up to 50% are autonomous see also: thyroid carcinoma, cold thyroid nodule (12 Dec 1998) |
| pyramid of thyroid | <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) |
| sternocleidomastoid branch of superior thyroid artery | <anatomy, artery> Branch of superior thyroid artery to sternocleidomastoid muscle. Synonym: ramus sternocleidomastoideus arteriae thyroideae superioris. (05 Mar 2000) |
| superior horn of thyroid cartilage | One of the pair of upward prolongations from the thyroid cartilage to which the lateral hyothyroid ligament attaches. Synonym: cornu superius cartilaginis thyroideae. (05 Mar 2000) |
| superior thyroid artery | <anatomy, artery> Origin, external carotid; branches, infrahyoid, superior laryngeal, sternocleidomastoid, cricothyroid, and two terminal branches. Synonym: arteria thyroidea superior. (05 Mar 2000) |
| superior thyroid notch | A deep notch in the middle of the upper border of the thyroid cartilage. Synonym: incisura thyroidea superior. (05 Mar 2000) |
| superior thyroid plexus | An autonomic plexus on the artery of the same name, derived from the external carotid plexus. Synonym: plexus thyroideus superior. (05 Mar 2000) |
| superior thyroid tubercle | A blunt projection on the lamina of the thyroid cartilage on either side at the superior end of the oblique line. Synonym: tuberculum thyroideum superius. (05 Mar 2000) |
| superior thyroid vein | <anatomy, vein> Receives blood from the upper part of the thyroid gland and larynx, accompanies the artery of the same name, and empties into the internal jugular vein. Synonym: vena thyroidea superior. (05 Mar 2000) |
| discordant thyroid nodule | <radiology> Hot on Tc-99m pertechnetate, cold on I-123 or I-131, indicates trapping, but no organification, same work-up as cold nodule (12 Dec 1998) |
| immunoglobulins, thyroid-stimulating | Autoantibodies that bind to the thyroid-stimulating hormone (tsh) receptor (receptors, thyrotropin) on thyroid epithelial cells. The autoantibodies mimic tsh causing an unregulated production of thyroid hormones characteristic of graves' disease. (12 Dec 1998) |
| inferior horn of thyroid cartilage | One of the pair of downward prolongations at the back of the thyroid cartilage; it articulates on each side with the cricoid cartilage. Synonym: cornu inferius cartilaginis thyroideae. (05 Mar 2000) |
| inferior thyroid artery | <anatomy, artery> Origin, terminal branch of thyrocervical trunk (with ascending cervical artery); branches, inferior laryngeal, and muscular, oesophageal, and tracheal. Synonym: arteria thyroidea inferior. (05 Mar 2000) |