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Webster 1913 Edition
Mediastinum
{
Meˊdi-as′tine
, ‖Meˊdi-as-ti′num
, }Noun.
[NL.
mediastinum
, fr. L. medius
middle; cf. mediastinus
helper, a menial servant, LL. mediastinus
equiv. to medius
: cf F. médiastin
.] (Anat.)
A partition; a septum; specifically, the folds of the pleura (and the space included between them) which divide the thorax into a right and left cavity. The space included between these folds of the pleura, called the mediastinal space, contains the heart and gives passage to the esophagus and great blood vessels.