Jacks test is a test that clinicians often use to check the integrity of the arch of the foot and its associated windlass mechanism. To do the test, you need to get the person standing and then grab the big toe and lift it up. As this happen the arch of the foot should come up naturally. This is how the arch of the foot supports itself during gait. The purpose of Jacks test is to make sure that this process is working properly. It is assumed that the big toe should be easy to lift up, as this means that the arch can establish itself easier and the heel can come off the ground much easier.
Famous Words of Inspiration...
"I've had a wonderful time, but this wasn't it."