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== Parathyroid ==

In most individuals there are four parathyroid glands lying on the dorsal portion of the thyroid, embedded in a true capsule, thus separate from the thyroid. Ectopic parathyroids may be found anywhere from the base of the skull to the arch of the aorta, specifically in the thymus, in the cervical area external to the thyroid and in the mediastinum. The parathyroids have a rich blood supply although not as extensive as the thyroid. Developmentally, the superior pair of parathyroids forms from the endodermal 4th pharyngeal pouches (these parathyroids referred to as parathyroids IV); the inferior pair develop from the 3rd pharyngeal pouches (parathyroids III), as does the thymus. This fact explains the ectopic or aberrant occurrence of parathyroids in the thymus.

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== Suprarenal (Adrenal) Glands ==