Passive dorsiflexion and plantar flexion?

Hey, I don't understand the mechanism behind passive dorsiflexion and plantar flexion at all. I can read that "In passive dorsiflexion in the anke joint, the muscles ventrally of the movement axis will relax and those dorsally of the axis will contract". That does not make any sense. If tibialis anterior relaxes (ventrally), then gastrocnemius (dorsally) will contract? That would give a plantar flexion and not a dorsiflexion. I'm seriously confused.
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums