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WordNet
middle thyroid vein

n. a vein on each side that drains the lateral part of the thyroid and empties into the internal jugular vein

Wikipedia
Middle thyroid vein

The middle thyroid vein collects the blood from the lower part of the thyroid gland, and after being joined by some veins from the larynx and trachea, ends in the lower part of the internal jugular vein.