Also found in: Dictionary, Thesaurus, Encyclopedia.
mediastinaPlural of mediastinum.
mediastinum(me?de-as-ti'num) plural.mediastina [L., in the middle]
1. A septum or cavity between two principal portions of an organ.
2. The mass of organs and tissues separating the lungs. It contains the heart and its large vessels, trachea, esophagus, thymus, lymph nodes, and connective tissue.
The thickened portion of the tunica albuginea on posterior surface of the testis. Synonym: corpus highmorianum