From the Guidelines
The thymus is the organ that is located in both the superior mediastinum and the anterior mediastinum. The thymus is a specialized primary lymphoid organ that plays a crucial role in the development of T-lymphocytes, which are essential for cell-mediated immunity. Anatomically, the thymus extends from the lower part of the neck and upper part of the chest, spanning across both the superior mediastinum (the upper portion of the mediastinum above the pericardium) and the anterior mediastinum (the region in front of the pericardium and great vessels). In contrast, the thyroid gland is located in the anterior neck region, wrapping around the trachea just below the larynx, while the parathyroid glands are typically found embedded in the posterior surface of the thyroid gland. Neither the thyroid nor parathyroid glands extend into the mediastinum under normal anatomical conditions.
Some studies, such as those on parathyroid adenoma 1, discuss the evaluation and localization of parathyroid glands, but they do not change the fact that the thymus is the organ located in both the superior and anterior mediastinum. The provided evidence focuses on the diagnosis and treatment of parathyroid-related conditions, but it does not provide information that would alter the anatomical locations of the thymus, thyroid gland, or parathyroid glands.
Key points to consider:
- The thymus plays a crucial role in the development of T-lymphocytes.
- The thymus is located in both the superior and anterior mediastinum.
- The thyroid gland and parathyroid glands have different locations and are not typically found in the mediastinum. The most recent and highest quality studies provided do not offer any new insights that would change the anatomical fact that the thymus is the organ located in both the superior and anterior mediastinum 1.
From the Research
Location of Thyroid Gland, Parathyroid Glands, and Thymus
- The thyroid gland is typically located in the neck, outside of the mediastinum 2.
- The parathyroid glands, including the superior and inferior parathyroid glands, are usually located near the thyroid gland, but can also be found in the mediastinum, particularly in the case of the inferior parathyroid gland which can descend into the anterior mediastinum 3.
- The thymus is an organ that is located in both the superior and anterior mediastinum, extending from the thoracic inlet to the diaphragm 2, 4, 5.
Mediastinum Subdivisions
- The mediastinum can be subdivided into different compartments, including the superior mediastinum, anterior mediastinum, middle mediastinum, and posterior mediastinum 2.
- The anterior mediastinum is defined as the region posterior to the sternum and anterior to the heart and brachiocephalic vessels, and contains the thymus gland, fat, and lymph nodes 2.
Structures Located in the Anterior Mediastinum
- The thymus gland is a characteristic anterior mediastinal structure that can be identified on computed tomographic (CT) scans 4.
- The anterior mediastinum can also contain other structures, including fat, lymph nodes, and occasionally, expansile lesions of the thymus 6.
- The inferior parathyroid gland can be located in the anterior mediastinum, particularly in cases where it has descended from its normal location near the thyroid gland 3.