Gland
Inferior parathyroid gland
Calcium-regulating gland with a variable migration endpoint
High-yield
Inferior describes the usual adult position; third-pouch origin explains why an inferior gland can lie away from the thyroid.
Overview
The inferior parathyroids develop from the third pharyngeal pouches and descend with the thymic primordia. They often settle near the lower thyroid poles, but their longer migration helps explain locations within the thymus or upper mediastinum. Most people have four parathyroid glands in total, with variation in both number and position.
Reference facts
- Location
- Usually near the lower thyroid pole, often anterior to the recurrent laryngeal nerve's plane; ectopic positions follow the thymic migration route.
- Hormones
- Parathyroid hormone, mainly produced by chief cells.
- Blood supply
- Usually inferior thyroid arterial branches; ectopic glands may recruit vessels from their local surroundings.
- Innervation
- Autonomic fibers accompany vessels. Circulating ionized calcium, detected by calcium-sensing receptors, is the main secretory regulator.
- Function
- Helps maintain extracellular calcium through kidney and bone effects and increased renal activation of vitamin D; promotes renal phosphate excretion.
Clinical correlation
An ectopic hyperfunctioning gland can produce hyperparathyroidism despite an unremarkable usual location. Loss or poor perfusion of enough parathyroid tissue can instead cause hypocalcemia, sometimes with tingling or muscle spasms.
Frequently asked questions
Where is the inferior parathyroid gland located?
Usually near the lower thyroid pole, often anterior to the recurrent laryngeal nerve's plane; ectopic positions follow the thymic migration route.
What does the inferior parathyroid gland secrete?
The inferior parathyroid gland secretes parathyroid hormone, mainly produced by chief cells.
What does the inferior parathyroid gland do?
Helps maintain extracellular calcium through kidney and bone effects and increased renal activation of vitamin D; promotes renal phosphate excretion.
What is the blood supply of the inferior parathyroid gland?
Usually inferior thyroid arterial branches; ectopic glands may recruit vessels from their local surroundings.