It admits vascular and respiratory structures. Convex surface of lung next to ribs called costal surface. Right lung has also a transverse fissure. On left lung the oblique fissure divides upper and lower lobes of lung. So, there are 5 lobes.
Inner layer is pulmonary pleura.
It adheres firmly to the lung. Pleural cavity is the potential, not actual space between the membrane. Serous fluid is secreted by the cells of the serous membrane and provides an antifriction lubricant. Pnuemothorax is the puncture of the lungs pleural lining resulting in its collapse. Atelectasis is collapse of lung or part of it.