Thyroid Gland Anatomy Overview

Thyroid Gland Anatomy

The thyroid gland is a butterfly-shaped endocrine gland located in the anterior neck, surrounded by the hyoid bone and the trachea. It consists of two lateral lobes connected by a central mass called the isthmus, which comes into continuity with the thyroglossal duct remnants. The thyroid gland plays a crucial role in regulating metabolism through its synthesis of three hormones: triiodothyronine (T3), tetraiodothyronine (T4), and calcitonin.

Structure

Follicular Cells

Follicular cells constitute about 95% of the total cell population of the thyroid gland. They are responsible for the production and secretion of T3 and T4 hormones, also known as thyroid hormones. These hormones play essential roles in maintaining basal metabolic rate, growth development, body temperature, heart function, etc..

Parafollicular Cells

Parafollicular cells, also known as parathyroidoid-producing cells or C cells, represent less than 5% of the total cell population and are more abundant in the upper part of the thyroid gland. These cells produce and secrete calcitonin, a peptide hormone involved in calcium homeostasis and regulation of insulin and glucagon levels.

Blood Supply

The thyroid gland receives blood from both sides via the superior thyroid artery and the inferior thyroid artery. The superior thyroid artery branches off the external carotid artery, while the inferior thyroid artery originates directly from the thyrocervical trunk. Both these blood vessels supply oxygen and nutrients to the thyroid gland, facilitating the various cellular processes within it.

In summary, the thyroid gland is a complex organ composed of follicular and parafollicular cells, each playing unique roles in the production of thyroid and calcitonin hormones. Its structure allows for efficient blood flow to support these vital functions, making it an integral component of human physiology.