The Principal Bronchus is the Center

The Vishnu Purana: Book II: Chapter II

Jambu-dwipa is in the centre of all these: and in the centre of this continent is the golden mountain Meru.

Mt Meru is located at the very center of Jambudvipa, the innermost sheath of the earth-lotus,

The principal bronchus is Meru

Meru, the principal bronchus, is regarded as "center" of the Jambu continent. The secondary bronchi ("mountains") that emanate / project outwards from Meru, and the other lower-level bronchi, must therefore be seen as becoming increasingly remote from this center. A clue is obtained from this passage regarding the situation of the continents beginning with Jambu. Jambu must be the region containing the main-stem and upper-level bronchi; the other continents--Plaksa and the rest--should be regions containing the lower-level bronchi. [proximal to distal movement along the bronchial tree / the unfolding of the respiratory lotus]