The thyroid gland is found in front of the trachea (wind pipe) in your neck. The thyroid cartilage, which is the largest cartilage of the larynx (voice box) lies just above the thyroid gland. The gland is divided into 2 lobes (right and left) and is connected in the middle by a thin bridge of thyroid tissue, known as the isthmus. Because of the 2 connected lobes, the thyroid has been described as being shaped like a butterfly, or a bow tie.
A normal-sized thyroid gland cannot be seen in the neck, and can barely be felt. It is only when certain conditions result in an enlarged thyroid gland (known as goitre), that a bulge may be seen or felt just underneath the Adam’s apple.
The primary function of your thyroid gland is to secrete thyroid hormones, which are responsible for controlling your body’s metabolism. The 2 main thyroid hormones are T3 (triiodothyronine) and T4 (thyroxine). The amount of thyroid hormones secreted is controlled by another hormone, called thyroid stimulating hormone (TSH), which is released from the pituitary gland in your head.
The thyroid hormones are involved in regulating many of your bodily functions, such as your heart rate, how quickly you burn calories, and digestion. Babies and children need adequate amounts of thyroid hormones for brain development and growth.
Your thyroid needs iodine (a chemical element that’s an essential part of our diet) in order to manufacture these thyroid hormones. Foods that are naturally rich in iodine include seafood and plants grown in iodine-rich soil. Iodised salt is another good source of dietary iodine.
Another hormone that’s produced in your thyroid gland is called calcitonin. This hormone, secreted by a small population of cells known as C cells, is involved in regulating the level of calcium in your blood.
Last Reviewed: 02 July 2009