Lab Value


Which of the following statements is true regarding the origin of the parathyroids?

The anatomy of the parathyroid gland is variable, and a thorough understanding of the embryologic and adult anatomy is essential in locating the glands during difficult preservations or resections (see the image).
The usual pattern for parathyroid glands is two superior parathyroid glands and two inferior thyroid glands, with each gland weighing 30–50 mg. The glands are normally oval and flat but change into a more globular state when abnormal. The superior glands arise from the fourth pharyngeal pouch with the lateral thyroid. Their location tends to be more uniform; they are located on the posterior surface of the capsule of the upper pole of the thyroid in proximity to where the recurrent laryngeal nerve enters the larynx. The inferior glands arise from the third pharyngeal pouch. These glands are more variable and can be found from the pharynx to the mediastinum but are most often located near the inferior thyroid margin. Occasionally, the parathyroid gland will be found completely embedded in the body of the thyroid.