mediastinum
noun
me·di·as·ti·num
ˌmē-dē-ə-ˈstī-nəm 
plural mediastina
ˌmē-dē-ə-ˈstī-nə
: the space in the chest between the pleural sacs of the lungs that contains all the tissues and organs of the chest except the lungs and pleurae
also
: this space with its contents
Examples of mediastinum in a Sentence
Recent Examples on the Web
According to the Dana-Farber Cancer Institute, this type of cancer usually starts in the upper chest area called the mediastinum.
—
Jordan Greene, Peoplemag, 23 Apr. 2024
The mediastinum of your body is a space that keeps your lungs and other chest structures (e.g., heart, esophagus, windpipe) separate.4
For example, two 2020 studies found that patients had swollen lymph nodes in the mediastinum area.
—Korin Miller, Health, 25 Sep. 2023
The swollen lymph nodes in the mediastinum were also associated with a higher risk of admission to an intensive care unit (ICU).
—Korin Miller, Health, 25 Sep. 2023
There was now significant air in the space between his lungs, known as the mediastinum, which had tracked up into his neck under the skin.
—Douglas G. Adler, Discover Magazine, 14 Dec. 2021
The mediastinum is ordinarily a sterile space, but easily becomes infected when an esophageal rupture occurs.
—Douglas G. Adler, Discover Magazine, 14 Dec. 2021
Based on the CT scan results, Matt’s mediastinum only seemed to have air in it and did not look to be infected just yet.
—Douglas G. Adler, Discover Magazine, 14 Dec. 2021
If leaked into the trachea, these contents could have led to pneumonia, or if into the mediastinum, to sepsis and vascular collapse.
—W Roy Smythe, Discover Magazine, 4 Oct. 2011
Limited-stage disease is used to describe lung cancer that’s only found within one lung, and may be found in the mediastinum between the lungs.
—Amanda MacMillan, Health.com, 23 July 2019
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Jordan Greene, Peoplemag, 23 Apr. 2024
The mediastinum of your body is a space that keeps your lungs and other chest structures (e.g., heart, esophagus, windpipe) separate.4
For example, two 2020 studies found that patients had swollen lymph nodes in the mediastinum area.
—Korin Miller, Health, 25 Sep. 2023
The swollen lymph nodes in the mediastinum were also associated with a higher risk of admission to an intensive care unit (ICU).
—Korin Miller, Health, 25 Sep. 2023
There was now significant air in the space between his lungs, known as the mediastinum, which had tracked up into his neck under the skin.
—Douglas G. Adler, Discover Magazine, 14 Dec. 2021
The mediastinum is ordinarily a sterile space, but easily becomes infected when an esophageal rupture occurs.
—Douglas G. Adler, Discover Magazine, 14 Dec. 2021
Based on the CT scan results, Matt’s mediastinum only seemed to have air in it and did not look to be infected just yet.
—Douglas G. Adler, Discover Magazine, 14 Dec. 2021
If leaked into the trachea, these contents could have led to pneumonia, or if into the mediastinum, to sepsis and vascular collapse.
—W Roy Smythe, Discover Magazine, 4 Oct. 2011
Limited-stage disease is used to describe lung cancer that’s only found within one lung, and may be found in the mediastinum between the lungs.
—Amanda MacMillan, Health.com, 23 July 2019
Cite this Entry
“Mediastinum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mediastinum. Accessed 23 Jun. 2025.
Copy CitationMedical Definition
mediastinum
noun
me·di·as·ti·num
ˌmēd-ē-ə-ˈstī-nəm
plural mediastina
-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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