The grouping of four small glands, about 5 mm in diameter, which lie to the side of and behind the thyroid gland. These glands regulate the metabolism of calcium and of phosphorus. If for any reason there is a deficiency of the secretion of the parathyroid glands, the amount of calcium in the blood falls too low and the amount of phosphorus increases. The result is the condition known as tetany characterized by restlessness and muscle spasms sometimes severe. The condition is checked by the injection of calcium gluconate, which causes an increase in the amount of calcium in the blood.
Any of the four tiny endocrine glands located behind the thyroid gland in the neck.