oculomotor

When you look at an object, you're using several muscles to move both eyes to focus on it. If you have a problem with the muscles, the eyes don't work properly.

There are many kinds of eye movement disorders. Two common ones are:

• Strabismus - a disorder in which the two eyes don't line up in the same direction. This results in "crossed eyes" or "walleye."
• Nystagmus - fast, uncontrollable movements of the eyes, sometimes called "dancing eyes"

Some eye movement disorders are present at birth. Others develop over time and may be associated with other problems, such as injuries. Treatments include glasses, patches, eye muscle exercises, and surgery. There is no cure for some kinds of eye movement disorders, such as most kinds of nystagmus.

When you play the piano or hit a tennis ball you are activating the cerebellum. The cerebellum is the area of the brain that controls coordination and balance. Problems with the cerebellum include:

• Cancer
• Genetic disorders
• Ataxias - failure of muscle control in the arms and legs that result in movement disorders
• Degeneration - disorders caused by brain cells decreasing in size or wasting away

Treatment of cerebellar disorders depends on the cause. In some cases, there is no cure but treatment may help with symptoms.

NIH: National Institute of Neurological Disorders and Stroke