The parathyroid glands
Parathyroid glands · glandulae parathyroideae
Four grain-sized glands behind the thyroid that control the calcium in your blood.
What it does
Usually four tiny parathyroid glands sit on the back of the thyroid. When blood calcium falls, they release parathyroid hormone, which draws calcium from bone, saves it in the kidneys and boosts its absorption from food via vitamin D.
Surprising fact
They were one of the last major organs to be identified in humans, and each is only about the size of a grain of rice.
Why it matters
Calcium controls nerves and muscles, so if the parathyroids are accidentally removed during thyroid surgery, low calcium can cause tingling and muscle cramps.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.