Why does tuberculosus lodge at the apex of the lungs?

More oxygen at apex: There is more ventilation and less blood flow at the apex of the lung. Since tuberculosis is a strict aerobe it grows better in the better oxygenated upper lobe where less of the oxygen is carried away be the blood. The lower lobes of the lung have more blood flow and less ventilation so there is less oxygen to feed the TB because the blood carries more of the oxygen into the body.