"Tegmentum originates from the Latin for covering."
"The tegmentum is one of the areas of the brainstem. It is a phylogenetically old part of the brainstem and, in adults, is the location of the brainstem nuclei 1. It is located centrally between the distinctive basal (ventral) features of the midbrain, pons and medulla, and the ventricular system (aqueduct and fourth ventricle) dorsally and contains the cranial nerve nuclei and reticular formations and ascending tracts 1,2."