Endothoracic fascia

The endothoracic fascia is deep to the intercostal space

The endothoracic fascia is the layer of loose connective tissue deep to the intercostal spaces and ribs, separating these structures from the underlying pleura. This fascial layer is the outermost membrane of the thoracic cavity. The endothoracic fascia contains variable amounts of fat. It becomes more fibrous over the apices of the lungs as the suprapleural membrane. It separates internal mammary artery from pleura.

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)