personal trainer on your iPhone or iPod, to guide you through vestibular rehabilitation for dizziness. Dermatomes is a handy reference map of which spinal nerve roots relay sensation from particular areas of the skin. OptOK is a universal toolkit for eye examination that includes acuity, reading, and optokinetic nystagmus tests. Myotomes is a quick reference guide to the neurological motor examination. It lists the commonly tested movements of the upper and lower limbs, and the nerve roots, muscles, and nerves that they test.