摘要
The thyroid is a butterfly-shaped organ that sits below the thyroid cartilage and in front of the trachea,in the throat.The thyroid gland serves a vital function through the secretion of thyroid hormone,a substance that is essential to life.Four smaller parathyroid glands are typically embedded in the back of the thyroid gland-these glands do not directly affect thyroid functions,but help control calcium levels in the body.
