Parathyroid Glands

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There are four parathyroid glands located in the anterior neck. They are yellow, oval glands that secrete parathyroid hormone (PTH), which increases serum calcium levels.

Gross Anatomy

The two pairs of parathyroid glands lie on the posterior surface of the lateral lobes of the thyroid gland, within the same fascicular corpuscle. Their location is variable, with the two superior parathyroid glands usual level with the middle of the posterior thyroid border and the two inferior parathyroid glands on the inferior poles of the thyroid.


During development the superior parathyroid glands are derived from the third pharyngeal pouch and the inferior parathyroid glands from the fourth pharyngeal pouch. They translocation during development to their adult location.


The chief cells of the parathyroid gland produce PTH, which increases the activity of osteoclasts in bones, the resorption of calcium in the kidneys and increases calcium from the small intestine to increase serum calcium levels. PTH also decreases reabsorbtion of phosphate in the kidneys. Oxyphil cells are also found in the parathyroid gland, their function is not known.


The main artery supplying the posterior thyroid and parathyroid glands is the inferior thyroid artery. There is also some collateral arterial supply from the superior thyroid artery. The venous drainage of the parathyroid glands is into the thyroid venous plexus.


Fibres innervating the parathyroid glands arise from the superior and middle cervical sympathetic ganglia. The nervous supply is vasomotor in nature, the endocrine secretions of the parathyroid glands are regulated hormonally. Lymphatic  drainage of the parathyroid glands is the same as the thyroid gland, into the cervical and paratracheal nodes.

Clinical Anatomy

Ectopic parathyroid glands - As the parathyroid gland have a highly variable location and develop from the pharyngeal pouches they sometimes can be situated in adults high in the neck or the thorax. These adenomas can be found using a SPECT scan.


Parathyroid damage during surgery - The variable location of the parathyroid glands increases the risk of them being removed or damaged during surgery. During a thyroidectomy surgeons may preserve some of the posterior thyroid gland to prevent damage to the parathyroid glands. Without the parathyroid glands the patient would become hypocalaemic leading to tetany, which can be fatal without urgent medical treatment.

Quick Anatomy

Key Facts


Developmental precursor

Arterial supply

Venous drainage

Nervous supply

Lymphatic drainage

Third pharyngeal pouch (inferior parathyroid glands), fourth pharyngeal pouch (superior parathyroid glands).

Superior and inferior thyroid arteries.

Superior, middle and inferior thyroid veins.

Superior and middle cervical sympathetic ganglia.

Mainly deep cervical nodes. Some into paratracheal nodes.


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The four parathyroid glands lie deep on the posterior surface of the thyroid gland. Parathyroid chief cells produce PTH, which acts on the proximal convoluted tubules of the kidney, the small intestines and osteoclasts to increase serum calcium. Their variable location and translocation during embryological development can lead to problems in surgery or ectopic parathyroid glands. The blood supply, drainage and innervation to the parathyroid glands is similar to the posterior thyroid gland.


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