The activity of the diaphragm and external intercostal muscles is regulated by the in the brain.

The answer is medulla and pons. There is a respiratory center in both regions of the brain stem. The dorsal and ventral respiratory groups of nerves emanate from medulla while the pontine respiratory group from the pons.
The dorsal and ventral respiratory groups stimulate the intercoastal and phrenic nerves of the diaphragm. The pontine regulate the rhythm and depth of breath

Because the earth is not round ,but it may seem round when viewed from ,our planet but true some points earth is not round was an oblate spheroid -a square that it squashed as globe however is not even a perfect oblate spheroid.in fact isaac newton's first proposed that earth was not perfectly round but it was an oblate spheroid instead.that mean a square that is squashed as its poles and swollen at the