The position of (fill in the blank) influences the rest of your alignment. Because our body is interconnected, one structure’s alignment will influence another’s. For example when your pelvis is out of alignment, it pulls your spine out of its natural alignment. The spine’s position effects the position of your ribcage, head and neck, as well as further down your chain in your knee and ankle joints. Basically your center of gravity is thrown off.
When you’re misaligned, muscles pull you in directions you otherwise wouldn’t be in, to fight for “balance” and trick your brain into thinking everything’s positioned where it needs to be. You’re alignment (or lack of) influences how well you stand and move, and that influences how your body responds to its environment, functionally or dysfunctionally. The latter leads to pain and injury.