Why are the left and right lungs two different sizes?
The right lung is larger and has more lobes than the left lung (3 vs 2) because the heart is normally located on the left side, and takes up space where the lung would have been. The right lung, which is heavier than the left, is also shorter (the right dome of the diaphragm being higher) and wider (the heart bulging more to the left). Each lung has an apex, three surfaces (costal, medial, and diaphragmatic), and three borders (anterior, inferior, and posterior). The right lung is divided into upper, middle, and lower lobes by oblique and horizontal fissures, whereas the left lung has usually only upper and lower lobes, separated by an oblique fissure.
