Boundaries of posterior mediastinum and describe its general topography

Boundaries of the Posterior Mediastinum:

1. Anterior Boundary:
   • The posterior mediastinum is anteriorly bounded by the posterior aspect of the pericardium and the anterior surfaces of the structures in the middle mediastinum, primarily the heart.
2. Posterior Boundary:
   • The posterior boundary is formed by the anterior surface of the vertebral column, including the thoracic vertebrae (T5 to T12) and the intervertebral discs between them.
3. Lateral Boundaries:
   • Laterally, the mediastinum is bounded by the parietal pleura covering the sides of the thoracic cavity.
4. Superior Boundary:
   • The superior boundary is not sharply defined, but it extends upward to the thoracic inlet, which is formed by the first rib, manubrium of the sternum, and the first thoracic vertebra (T1).
5. Inferior Boundary:
   • The inferior boundary is the diaphragmatic surface of the posterior mediastinum, extending to the diaphragm.

General Topography of the Posterior Mediastinum:

1. Location:
   • The posterior mediastinum is located posterior to the pericardium and heart, between the anterior surface of the vertebral column and the posterior surface of the pericardium.
2. Structures:
   • Contains a diverse array of structures including the esophagus, thoracic aorta, thoracic duct, azygos and hemiazygos veins, sympathetic trunks, vagus nerves, and thoracic splanchnic nerves.
3. Esophagus and Aorta:
   • The esophagus runs through the posterior mediastinum in close proximity to the vertebral column, posterior to the trachea.
   • The thoracic aorta descends through the posterior mediastinum, running parallel to the vertebral column.
4. Lymphatic Structures:
   • The thoracic duct, responsible for draining lymph from the lower and left sides of the body, ascends through the posterior mediastinum.
   • Azygos and hemiazygos veins, major venous vessels, course through the posterior mediastinum.
5. Nervous Structures:
   • The sympathetic trunks run along the vertebral column and contribute to the sympathetic nervous system.
   • Vagus nerves travel alongside the esophagus, providing parasympathetic innervation to various thoracic and abdominal organs.
   • Thoracic splanchnic nerves transmit autonomic signals to abdominal organs.
6. Relations:
   • The structures in the posterior mediastinum are closely related to each other, and their positions are influenced by the vertebral column, pleura, and pericardium.

Clinical Significance:

• Disorders affecting the posterior mediastinum, such as esophageal disorders, aortic aneurysms, thoracic duct injuries, and neurological conditions involving the sympathetic and parasympathetic systems, may require evaluation and management.

Understanding the boundaries and general topography of the posterior mediastinum is essential for clinicians, particularly in the context of diagnosing and treating conditions related to this region within the thoracic cavity. Imaging studies, such as CT scans or MRIs, are often utilized for detailed visualization of the structures in the posterior mediastinum.