Which body cavity can be subdivided into four quadrants and nine regions: ?

The answer is abdominopelvic cavity

Abdomen is divided into four quadrants and nine regions to make diagnosis and examination of a disease easier. Every quadrants/region has a group organ that might be related to the disease. Since liver is normally located in the upper right, it will be less likely to be found on the lower right quadrant/region.

for the points

no i don't feel that humans have oversubscribed some medications