Hands in your pockets
Oblique (oh-BLEEK) means slanted. These muscles run on a slant across your sides.
The outer obliques run down and toward the middle, the same way your fingers point when you slide your hands into your front pockets.
Under them, the inner obliques run the other way. The two layers crisscross, like the threads in a woven basket. That makes them extra strong.
Twist and bend
Try it: put your hands on your sides and twist to look behind you. Feel the muscles tighten?
Now bend sideways, like a teapot pouring out tea. Your side muscles did that too.
You use your obliques when you throw a ball, swing a bat, dance or spin a hula hoop.
A muscle belt
The deepest belly muscle of all is the transverse abdominis (trans-VERS ab-DOM-ih-nis). Its fibers run straight across your middle, like a wide belt.
It hugs your middle tight to hold your insides in place and keep your back steady.
Try it: put your hands on your belly and pretend to blow up a big balloon. Feel your belly pull in? That's your belt muscle.
Four muscles, one wall
The front straps (your abs), the outer obliques, the inner obliques and the belt muscle make your belly wall together.
Each layer runs a different way. Layers going different ways make the wall strong, the same reason a basket's crisscross weave is strong.