The |thyroid| gland is one of the |glands| of the endocrine system which lies outside of a body cavity. It is a small gland weighing about 1 ounce (28 grams) and is located in the neck, just below the |larynx|. It is somewhat heavier in females and becomes enlarged during menstration and |pregnancy|. The gland is divided into two |lobes|, a right |lobe| and a left |lobe|, each of which is about two inches in length. These |lobes| are connected by a bridge called the isthmus, which is about an inch in length and width. The isthmus connects the lower two-thirds of the |lobes| and covers the second and third rings of the |trachea|.
