The brain, spinal cord, and nerves make up the nervous system. Together they control all the workings of the body. When something goes wrong with a part of your nervous system, you can have trouble moving, speaking, swallowing, breathing, or learning.  You can also have problems with your memory, senses, or mood.
There are more than 600 neurologic diseases. Major types include
   Diseases caused by faulty genes, such as Huntington's disease and muscular dystrophy
   Problems with the way the nervous system develops, such as spina bifida
   Degenerative diseases, where nerve cells are damaged or die, such as Parkinson's disease and Alzheimer's disease
   Diseases of the  blood vessels that supply the brain, such as stroke
   Injuries to the spinal cord and brain
   Seizure disorders, such as epilepsy 
   Cancer, such as brain tumors
   infections, such as meningitis