The parathyroid glands are embedded in the posterior surface of the thyroid gland. There are usually four parathyroid glands—two pairs—on each side of the thyroid. The parathyroid glands are tiny, pea-shaped glands weighing only a total of 0.06 ounces (1.6 grams) together. Each measures approximately 0.1 to 0.3 inches (3 to 8 millimeters) in length, 0.07 to 0.2 inches (2 to 5 millimeters) in width, and 0.05 inches (1.5 millimeters) in depth.