Final answer:
The inferior surface of the pericardial sac and the parietal pleura line the thoracic walls and the thoracic surface of the diaphragm, fusing onto the central tendon and contributing to breathing functions.
Step-by-step explanation:
The structures that line the thoracic walls and the thoracic surface of the diaphragm are primarily composed of the pleural membranes (parietal pleura) and the inferior surface of the pericardial sac. These membranes fuse onto the central tendon of the diaphragm, which is surrounded by the skeletal muscle portions that aid in the contraction and relaxation essential for breathing.
The diaphragm is also crucial for separating the thoracic cavity from the abdominal cavity, with its superior surface being convex to provide the floor of the thoracic cavity, and the inferior surface being concave to form the roof of the abdominal cavity.
Additionally, the diaphragm features openings that allow for the passage of key structures such as the inferior vena cava, esophagus, and aorta.