The mediastinum lies within the
thorax and is enclosed on the right and left by
pleurae. It is surrounded by the chest wall in front, the
lungs to the sides and the
spine at the back. It extends from the
sternum in front to the
vertebral column behind.[3][4] It contains all the organs of the thorax except the lungs.[4][5] It is continuous with the loose connective tissue of the
neck.
The mediastinum can be divided into an upper (or superior) and lower (or inferior) part:
The inferior mediastinum from this level to the
diaphragm. This lower part is subdivided into three regions, all relative to the
pericardium – the anterior mediastinum being in front of the pericardium, the middle mediastinum contains the pericardium and its contents, and the posterior mediastinum being behind the pericardium.[6]
Anatomists,
surgeons, and clinical
radiologists compartmentalize the mediastinum differently. For instance, in the radiological scheme of Felson, there are only three compartments (anterior, middle, and posterior), and the heart is part of the middle (inferior) mediastinum.[7][page needed]
inferiorly by the transverse thoracic plane. which is an imaginary plane passing from the sternal angle anteriorly to the lower border of the body of the 4th thoracic vertebra posteriorly;
Middle mediastinum: lymphadenopathy, metastatic disease such as from small cell carcinoma from the lung.
Posterior mediastinum: Neurogenic tumors, either from the nerve sheath (mostly benign) or elsewhere (mostly malignant).
Mediastinitis is
inflammation of the tissues in the mediastinum, usually
bacterial and due to rupture of organs in the mediastinum. As the infection can progress very quickly, this is a serious condition.
Pneumomediastinum is the presence of air in the mediastinum, which in some cases can lead to
pneumothorax,
pneumoperitoneum, and
pneumopericardium if left untreated. However, that does not always occur and sometimes those conditions are actually the cause, not the result, of pneumomediastinum. These conditions frequently accompany
Boerhaave syndrome, or spontaneous
esophageal rupture.
Widened mediastinum/mediastinal widening is where the mediastinum has a width greater than 6 cm on an upright PA
chest X-ray or 8 cm on supine AP chest film.[11]
A widened mediastinum can be indicative of several pathologies:[12][13]
^Cheng, Guang-Shing; Varghese, Thomas K.; Park, David R. (2016-01-01), Broaddus, V. Courtney; Mason, Robert J.; Ernst, Joel D.; King, Talmadge E. (eds.),
"83 - Mediastinal Tumors and Cysts", Murray and Nadel's Textbook of Respiratory Medicine (Sixth Edition), Philadelphia: W.B. Saunders, pp. 1478–1495.e38,
doi:
10.1016/b978-1-4557-3383-5.00083-x,
ISBN978-1-4557-3383-5, retrieved 2020-11-17
^Geusens; Pans, S.; Prinsloo, J.; Fourneau, I. (2005). "The widened mediastinum in trauma patients". European Journal of Emergency Medicine. 12 (4): 179–184.
doi:
10.1097/00063110-200508000-00006.
PMID16034263.
^Gideon P. Naudé; Fred S. Bongard; Demetrios Demetriades (2003).
Trauma secrets. Elsevier Health Sciences. pp. 95–.
ISBN978-1-56053-506-5. Retrieved 19 April 2010.
External links
Look up mediastinum in Wiktionary, the free dictionary.
Anatomy figure: 21:01-03 at Human Anatomy Online, SUNY Downstate Medical Center – "Divisions of the mediastinum."
Anatomy figure: 21:02-03 at Human Anatomy Online, SUNY Downstate Medical Center – "The anatomical divisions of the inferior mediastinum."
thoraxlesson3 at The Anatomy Lesson by Wesley Norman (Georgetown University) – "Subdivisions of the Thoracic Cavity"