The thyroid gland, glandula thyroidea, the largest of the endocrine glands in an adult, is located on the neck in front of the trachea and on the side walls of the larynx, partially adhering to the thyroid cartilage , from where it got its name. It consists of two lateral lobes, lobi dexter et sinister, and an isthmus, isthmus , lying transversely and connecting the lateral lobes near each other near their lower ends. A thin process called lobus pyramidaiis departs from the isthmus    that can extend to the hyoid bone. The upper part of the lateral lobes go to the outer surface of the thyroid cartilage, covering the lower horn and the adjacent portion of the cartilage, down to the fifth to sixth ring of the trachea; the isthmus with the posterior surface adjacent to the second and third rings of the trachea, sometimes reaching its cricoid cartilage with its upper edge. The posterior surface of the lobe is in contact with the walls of the pharynx and esophagus. The outer surface of the thyroid gland is convex, internal, facing the trachea and larynx, concave. In front, the thyroid gland is covered with skin, subcutaneous tissue, the fascia of the neck, giving the gland an external capsule, capcula fibrosa, and muscles: mm. sternohyoideus, sternothyroideus et omohyoideus. The capsule sends processes into the gland tissue, which divide it into lobules consisting of follicles, folliculi gl. thyroideae containing colloid (iodine-containing substance thyroidin in its composition).

In the diameter of the iron, it has about 50-60 mm, in the anteroposterior direction in the region of the lateral lobes 18-20 mm, and at the level of the isthmus 6-8 mm. The mass is about 30 – 40 g, in women the mass of the gland is slightly larger than in men, and sometimes periodically increases (during menstruation). In the fetus and in early childhood, the thyroid gland is relatively larger than in an adult.

Thyroid function.

The importance of the gland for the body is large. Her congenital underdevelopment causes myxedema and cretinism . The proper development of tissues, in particular the skeletal system, metabolism, functioning of the nervous system, and so on, depend on the hormone of the gland. In some places, a violation of the thyroid gland function causes the so-called endemic goiter. The hormone thyroxin produced by the iron accelerates the oxidation processes in the body, and thyrocalcitonin regulates the calcium content. With hypersecretion of the thyroid gland, there is a symptom complex called bazedovy disease.