This series of two articles is structured to provide anatomically accurate functional schematics of the motor and sensory innervation of the lower back, hip, and lower limb. This first paper provides radiographically oriented schematic axial sections of the lower back and hip in which the muscles are appropriately color-coded to match the peripheral nerves. A companion color-coded summary table allows prediction of unique patterns of denervation from 25 lesion sites. These are divided into three categories (roots T12 to S4, four plexal quadrants, and 11 sectional levels). Correlation between an imaging abnormality at one of these lesion sites and the predicted denervation pattern ensures the lesion is, in fact, clinically significant. The next article will continue this color-coded approach into the lower limb.