As early as the middle of the 16th century, the Italians in Europe first described the anatomical features of the thyroid gland and saw that it was shaped like the ancient “armor” used for defense in war, hence the name thyroid gland. The thyroid gland is located in the middle of the neck and is shaped like a butterfly with its wings spread out in front of the trachea and close to the larynx. The thyroid gland is located between the sternocleidomastoid muscles on the left and right sides and is divided into two lateral lobes connected by the isthmus, each 2.5-4.0 CM long, 1.5-2.0 CM wide and 1.0-1.5 CM thick. The normal adult thyroid gland weighs about 15 – 25 grams and is the largest of the endocrine glands in the body. The thyroid gland cannot be seen or felt in normal times, but it plays an important role in physiology.