Best way to compare two related dependent variables across two groups

[widit]

Hey

I'm in search of a statistical measure to use that can help me measure differences across two phenotypes. My two dependent variables are to a certain extent related. This is neuroscience research and for those of you who sort of know this field im trying to compare spine length and spine head volume across two phenotypes when i compare these two seperately i get some statistically significant results however when i make 3d histograms of the two groups there are CLEAR VISIBLE differences between the two groups when each spines length and corresponding head volume are taken into consideration.

PLEASE HELP ive been stuck on this for the past 4 months and don't know how to show this statistically.