The thyroid gland is an endocrine organ located in the front of the neck. It is shaped like a butterfly. It is located in the upper trachea where the second and third tracheal rings meet the isthmus of the sternum and extends to the fifth tracheal ring. The thyroid gland surrounds the tracheal rings and the cricoid cartilage under the laryngeal thyroid cartilage in two symmetrical lobes.

The thyroid gland is an endocrine organ located in the front of the neck. It is shaped like a butterfly. It is located in the upper trachea where the second and third tracheal rings meet the isthmus of the sternum and extends to the fifth tracheal ring. The thyroid gland surrounds the tracheal rings and the cricoid cartilage under the laryngeal thyroid cartilage in two symmetrical lobes. It is attached to the trachea by berry ligaments. The lobes of the thyroid gland are 5 x 2.5 x 2.5 cm in size and weigh about 25 grams. The thyroid gland is completely surrounded by two capsules. Extensions hanging from these capsules both separate the lobes and separate them into coils and lobules.

The thyroid gland is an organ with a much larger vascular network than the brain or kidney. While it receives blood with two veins from the top, it empties the blood with three veins from the bottom and has a special vascular network within itself. So much so that in hyperthyroidism, the blood flow in the thyroid gland may become audible as a murmur.



The thyroid nervus receives signals from the vagus and nervous system. These nerve connections carry functions related to the vascular structures rather than the hormonal work of the thyroid. Due to the functions of these nerves in the adjacent organs, their anatomical structures are very important during thyroid surgery.

Since the thyroid gland is surrounded or associated with dozens of muscles in the neck, it is a sensitive area that must be considered in terms of thyroid surgery.

The thyroid begins to settle and mature from the 7th week of the fetal period. Due to the differences in these processes, there may rarely be differences in placement or shape. Different locations are called ectopic thyroid. It is very important to detect ectopic locations and physical differences in terms of thyroid treatment and surgery. Ectopic thyroid tissues are discussed in another article.

The laryngeal nerves, which pass almost adjacent to the thyroid gland, are important nerves that must be protected due to their vocal cord functions. It is important to correctly locate and protect these laryngeal nerves before thyroid surgery. Because there is a possibility that they will be cut during surgery or be affected by cautery heat.

Enlarged thyroid glands can extend to the carotid arteries laterally, to the esophagus posteriorly, and to the lungs below. In this case, it will be necessary to pay attention to keep all neighboring structures healthy during surgical interventions.

Parathyroid glands are four glands on the posterior surface of the thyroid gland, two above and two below. The parathyroid glands are usually attached to the thyroid gland. In fact, sometimes abnormal conditions may develop and even settle into the thyroid gland. There is also the possibility that the parathyroid glands are often damaged during thyroid surgery.

Thyroid lobes are divided into thyroid lobules. Thyroid lobules are formed from thyroid follicles. Thyroid follicles are the main functional units of the thyroid gland and consist of follicular cells. Parafollicular cells are found between or in the walls of the thyroid follicles. These parafollicular cells in the thyroid are also called C cells.

Thyroid follicular cells secrete tetraiodothyronine (T4) (Thyroxine) and triiodothyronine (T3) hormones. Tetraiodothyronine (T4) (Thyroxine) is then converted into its active form, triiodothyronine (T3). Parafollicular cells (C cells) secrete the hormone calcitonin. Calcitonin is a hormone that acts as the opposite of parathormone.

Thyroid follicles are filled with a colloid called thyroglobulin, and these thyroglobulin areas are the storage area of the thyroid gland.