What anatomy is relevant in hyperparathyroidism?

Updated: Dec 24, 2020
  • Author: Lawrence Kim, MD, FACS, FACE; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Usually, 4 parathyroid glands are situated posterior to the thyroid gland. A small number of patients have 3, 5, or, occasionally, more glands. The glands are identified based on their location as right or left and superior or inferior.

The inferior glands are derived from the third pharyngeal pouch. This structure is also the embryologic origin of the thymus. Therefore, the inferior glands originate more cephalad than the superior glands, but they migrate along with the thymus to finally become situated more inferiorly than the superior glands. Because of their embryologic association with the thymus, the inferior glands are often found adjacent to or within the thymus. They are usually located near the inferior pole of the thyroid.

The superior glands are more consistent in location, usually found just superior to the intersection of the inferior thyroid artery and the recurrent laryngeal nerve. The superior glands are derived embryologically from the fourth pharyngeal pouch. This structure also gives rise to the C cells of the thyroid gland. Because of their embryologic origin, the superior glands are occasionally found within the substance of the thyroid gland. Ectopic locations of parathyroid glands are discussed in more detail in Surgical care in Primary Hyperparathyroidism.

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