Metathalamus
The metathalamus was a composite structure of the thalamus, consisting of the medial geniculate nucleus and the lateral geniculate nucleus.

In 2366, when Ambassador Sarek was believed to suffer from Bendii Syndrome, Dr. Beverly Crusher suggested the tentative diagnosis could be confirmed by growing a  from the tissue of his metathalamus. Unfortunately, it would have taken several days for the results to have come through, time they didn't have. ()

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Brain anatomy