The Anterior Mediastinum - Podcast Version TeachMeAnatomy 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The mediastinum is the central compartment of the thoracic cavity, located between the two pleural sacs. It contains most of the thoracic organs, and acts as a conduit for structures traversing the thorax on their way into the abdomen. Anatomically, the mediastinum is divided into two parts by an imaginary line that runs from the sternal angle (the angle formed by the junction of the sternal body and manubrium) to the T4 vertebrae: Superior mediastinum – extends upwards, terminating at the superior thoracic aperture. Inferior mediastinum – extends downwards, terminating at the diaphragm. It is further subdivided into the anterior mediastinum, middle mediastinum and posterior mediastinum. In this article, we shall look at the anatomy of the anterior mediastinum – its borders, contents and clinical correlations. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Borders The anterior mediastinum is bordered by the following thoracic structures: Lateral borders: Mediastinal pleura (part of the parietal pleural membrane). Anterior border: Body of the sternum and the transversus thoracis muscles. Posterior border: Pericardium. Roof: Continuous with the superior mediastinum at the level of the sternal angle. Floor: Diaphragm. By TeachMeSeries Ltd (2026) Fig 1The mediastina of the thorax. Contents The anterior mediastinum contains no major structures. It accommodates loose connective tissue (including the sternopericardial ligaments, which tether the pericardium to the sternum), fat, some lymphatic vessels, lymph nodes and branches of the internal thoracic vessels. In infants and children, the thymus extends inferiorly into the anterior mediastinum. However the thymus recedes during puberty and is mostly replaced by adipose tissue in the adult. By TeachMeSeries Ltd (2026) Fig 2The anatomical position of the thymus. It is mostly located in the superior mediastinum, but can extend into the anterior mediastinum. Do you think you’re ready? Take the quiz below Pro Feature - Quiz The Anterior Mediastinum Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 1800 More Questions Available Upgrade to TeachMeAnatomy Pro Challenge yourself with over 1800 multiple-choice questions to reinforce learning Learn More Frequent questions What is the anterior mediastinum? The anterior mediastinum is a subdivision of the inferior mediastinum, located between the sternum and the pericardium. It primarily contains loose connective tissue, fat, lymphatic vessels, lymph nodes, and branches of the internal thoracic vessels. What are the borders of the anterior mediastinum? The anterior mediastinum is defined by the body of the sternum and transversus thoracis muscles anteriorly, the pericardium posteriorly, mediastinal pleura laterally, and the diaphragm inferiorly. Its superior border connects with the superior mediastinum at the level of the sternal angle. What contents are found in the anterior mediastinum? The anterior mediastinum contains minimal major structures, primarily consisting of loose connective tissue, fat, lymphatic vessels, lymph nodes, and branches of the internal thoracic vessels. In children, the thymus can extend into this space, but it diminishes in size during puberty. What is the clinical significance of the anterior mediastinum? While the anterior mediastinum contains no significant organs, its contents can be clinically relevant in conditions involving lymphadenopathy or masses, particularly in paediatric patients where the thymus may be involved. Understanding its anatomy aids in diagnosing mediastinal pathologies. How is the mediastinum divided anatomically? The mediastinum is divided into superior and inferior sections by an imaginary line from the sternal angle to the T4 vertebra. The inferior mediastinum is further segmented into the anterior, middle, and posterior mediastinum, each with distinct anatomical features and contents. Rate This Article