Definition of "mediastinum" [mediastinum]

• The region in mammals between the pleural sacs, containing the heart and all of the thoracic viscera except the lungs. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "SATCHER: Well, the spores get into the lungs and they end up in the lymph nodes, in the chest, what we call the mediastinum (ph)."
• "The adjacent sides of the two pleural sacs are central to the thorax, and form that space which is called mediastinum; the heart is located in this mediastinum, U E, Plate 1."
• "It is applied to the tunica vasculosa over the glandular substance of the testis, and, at its posterior border, is reflected into the interior of the gland, forming an incomplete vertical septum, called the mediastinum testis (corpus Highmori)."