Parathyroid gland

Parathyroid glands

There are two pairs of glands (4 in total):

1. The superior glands: found at the superior pole of the thyroid, at the junction of cricoid and thyroid cartilages.
   
   
2. The inferior glands: found between the inferior poles of the thyroid lobes and the superior mediastinum.

Function:

• The Parathyroid gland monitors calcium levels, and when levels drop, it increases the secretion of parathyroid hormone (PTH).
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• Calcium acts in a negative feedback loop, to control the release of PTH - in normal physiology.

Vascular supply: Inferior thyroid artery

• This vessels course is alongside the recurrent laryngeal nerve and supplying the posterior portion of the thyroid gland and the superior and inferior parathyroid glands.

Embryology:

1. Superior parathyroid glands: derived from the fourth pharyngeal pouch.
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2. Inferior parathyroid gland: derived from the third pharyngeal pouch.

• ~~In DiGeorge syndrome, the third and fourth pharyngeal pouches fail to develop properly = aplastic parathyroid which cannot produce PTH.

Clinically relevant sections (links will be added once uploaded)

1. Hyperparathyroidism
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2. Hypoparathyroidism
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3. Pseudohypoparathyroidism