: The area between the lungs. The organs in this area include the heart and its large veins and arteries, the trachea, the esophagus, the bronchi, and lymph nodes.
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1. A septum between two parts of an organ or a cavity. 2. [TA] The median partition of the thoracic cavity, covered by the mediastinal part of the parietal pleura and containing all the thoracic viscera and structures except the lungs. It is divided arbitrarily into two major divisions: a superior m. [TA] (m. superus [TA]), which lies directly superior to a horizontal plane intersecting the sternal angle and approximately the T4–5 intervertebral disk, and an inferior m. [TA] (m. inferius [TA]) inferior to that plane; the latter is, in turn, subdivided in 3 parts: a middle m. [TA] (m. medium [TA]), which is coterminus with the pericardial sac containing the heart, a nearly potential anterior m. [TA] (m. anterius [TA]) lying in front, and a posterior m. [TA] (m. posterius [TA]) behind, containing the esophagus, descending aorta, and thoracic duct. SYN: interpleural space, interpulmonary septum, mediastinal space, septum mediastinale. [Mod. L. a middle septum, fr. Mediev. L. mediastinus, medial, fr. L. mediastinus, a lower servant, fr. medius, middle]
- anterior m. [TA] the narrow nearly potential space region between the pericardium posteriorly and the sternum anteriorly containing the thymus or its remnants, some lymph node s and vessels and branches of the internal thoracic artery. SYN: m. anterius [TA].
- m. anterius [TA] SYN: anterior m..
- inferior m. [TA] the region below a horizontal plane transecting approximately the T4–5 intervertebral disk posteriorly and the sternal angle anteriorly, demarcating the inferior limit of the superior m.. It is subdivided into three regions: middle, anterior, and posterior. SYN: m. inferius [TA].
- m. inferius [TA] SYN: inferior m..
- m. medium [TA] SYN: middle m..
- middle m. [TA] the large central portion of the inferior m., which includes the pericardium and the contained heart, as well as the phrenic nerves and cardiacophrenic vessels. SYN: m. medium [TA].
- posterior m. [TA] lies between the pericardium anteriorly and the vertebral column posteriorly and below the level of the plane that interesects the sternal angle and the T4–5 intervertebral disk. It contains the descending aorta, thoracic duct, esophagus, azygos veins, and vagus nerves. SYN: m. posterius [TA], postmediastinum.
- m. posterius [TA] SYN: posterior m..
- superior m. [TA] part of the m. lying superior to the horizontal plane intersecting the sternal angle and approximately the T4–5 intervertebral disc ( i.e., above the pericardium); it contains the arch of the aorta and the vessels arising from it, the brachiocephalic veins, and upper portion of the superior vena cava, the trachea, the esophagus, the thoracic duct, the thymus, and the phrenic, vagus, cardiac, and left recurrent laryngeal nerves. SYN: m. superius [TA].
- m. superius [TA] SYN: superior m..
- m. testis [TA] SYN: m. of testis.
- m. of testis [TA] a mass of fibrous tissue continuous with the tunica albuginea, projecting into the testis from its posterior border; testicular septa radiate as continuations surrounding the testicular lobules. SYN: m. testis [TA], corpus highmori, corpus highmorianum, Highmore body, septum of testis.

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me·di·as·ti·num .mēd-ē-ə-'stī-nəm n, pl -na -nə
1) the space in the chest between the pleural sacs of the lungs that contains all the viscera of the chest except the lungs and pleurae also this space with its contents

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the space in the thorax (chest cavity) between the two pleural sacs. The mediastinum contains the heart, aorta, trachea, oesophagus, and thymus gland and is divided into anterior, middle, posterior, and superior regions.

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me·di·as·ti·num (me″de-ə-stiґnəm) pl. mediastiґna [L.] a median septum or partition. [TA] the mass of tissues and organs separating the two pleural sacs, between the sternum anteriorly and the vertebral column posteriorly and from the thoracic inlet superiorly to the diaphragm inferiorly. It contains the heart and pericardium, the bases of the great vessels, the trachea and bronchi, esophagus, thymus, lymph nodes, thoracic duct, phrenic and vagus nerves, and other structures and tissues. The mediastinum is divided into a superior region and an inferior region that comprises anterior, middle, and posterior parts.

Subdivisions of the mediastinum.

Medical dictionary. 2011.

Look at other dictionaries:

  • Mediastinum — Mediastinum. The division between superior and inferior is at the sternal angle …   Wikipedia

  • Mediastīnum — (lat.), Mittelfell; daher Media stinītis, Mittelfellentzündung …   Pierer's Universal-Lexikon

  • Mediastīnum — (lat.), Mittelfell, s. Brustfell …   Meyers Großes Konversations-Lexikon

  • Mediastinum — Mediastīnum (lat.), das Mittel , Zwischenfell, das die Brusthöhle in zwei gleiche Teile teilt …   Kleines Konversations-Lexikon

  • Mediastinum —   [neulateinisch, zu lateinisch medius »mittlerer«] das, s/, Anatomie: das Mittelfell.   …   Universal-Lexikon

  • mediastinum — [mē΄dē as tī′nəm] n. pl. mediastina [mē΄dē as tī′nə] [ModL < ML mediastinus, in the middle (form infl. by L mediastinus, servant, medical assistant) < L medius, middle: see MID1] 1. a membranous partition between two cavities of the body,… …   English World dictionary

  • Mediastinum — Organe des Mediastinums Das Mediastinum, deutsch Mittelfell, ist ein senkrecht verlaufender Gewebsraum in der Brusthöhle. Es liegt in der Medianebene zwischen den beiden Pleurahöhlen und reicht vom Zwerchfell bis zum Hals. Das angrenzende… …   Deutsch Wikipedia

  • Mediastinum — Mediastine Me di*as tine, Mediastinum Me di*as*ti num, n. [NL. mediastinum, fr. L. medius middle; cf. mediastinus helper, a menial servant, LL. mediastinus equiv. to medius: cf F. m[ e]diastin.] (Anat.) A partition; a septum; specifically, the… …   The Collaborative International Dictionary of English

  • mediastinum — mediastinal, adj. /mee dee a stuy neuhm/, n., pl. mediastina / a stuy neuh/. Anat. 1. a median septum or partition between two parts of an organ, or paired cavities of the body. 2. the partition separating the right and left thoracic cavities,… …   Universalium

  • Mediastinum — Media|sti̱num [nlat. Bildung zu lat. medius = mittlerer] s; s, 1) „Mittelfell“, Mittelteil des Thoraxinnenraumes, der zwischen den beiden Pleurasäcken liegt und das Herz, die großen Gefäße, die Luftröhre und die Speiseröhre enthält. 2) in… …   Das Wörterbuch medizinischer Fachausdrücke

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