In the axial plane, the thoracic paravertebral space (TPS) is a triangle with the base turned towards the vertebral spine, the parietal pleura and the endothoracic fascia are the antero-lateral border and the internal intercostal membrane is the posterior border
The apex points into the intercostal space laterally
The TPS communicates with the epidural space via the intervertebral foramina, with the mediastinum antero-medially, and with the intercostal space laterally
The internal intercostal membrane is continuous with the internal intercostal muscle (between the external intercostal muscles and the innermost intercostal muscles) laterally and the superior costotransverse ligament medially
