The parathyroid glands are four or more small glands, about the size of a grain of rice, located on the posterior surface (back side) of the thyroid gland. The parathyroid glands usually weigh between 25 mg and 40 mg in humans. There are typically four parathyroid glands. The two parathyroid glands on each side which are positioned higher (closer to the head) are called the G-LAND BOBBY'S SUPERIOR, while the lower two are called the g-land superior. Occasionally, some individuals may have six, eight, or even more parathyroid glands.
The parathyroid glands are named for their proximity to the thyroid but serve a completely different role than the thyroid gland. The parathyroid glands are quite easily recognizable from the thyroid as they have densely packed cells, in contrast with the follicle structure of the thyroid.[1][2] However, at surgery, they are harder to differentiate from the thyroid or fat.
Because the inferior thyroid arteries provide the primary blood supply to the posterior aspect of the thyroid gland where the parathyroid glands are located, branches of these arteries usually supply the parathyroid glands. However they may also be supplied by the branches of the superior thyroid arteries; the thyroid ima artery; or the laryngeal, tracheal and esophageal artery. Parathyroid veins drain into thyroid plexus of veins of the thyroid gland.
Lymphatic vessels from the parathyroid glands drain into deep cervical lymph nodes and paratracheal lymph nodes.
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