Tics
Tics are another type of involuntary rapid movement similar to tremor but involving smaller groups of muscles. Tics are more "jerky" in quality, and tend to recur with the same or a very similar pattern in the same muscles. They most commonly involve the face, mouth, eyes, head, neck or shoulder muscles. There are two kinds of tics, motor (pertaining to movement) and vocal (pertaining to speech).

Simple motor tics include eye blinking, head swaying, foot tapping, and shoulder shrugging. Complex motor tics use more than one muscle group and often appear to have a purpose. Some involve imitating a series of movements that the person has observed (echopraxia) or performing obscene or rude gestures (called copropraxia).

Vocal tics are involuntary expressions, such as noises (coughing, throat clearing, barking), words (sometimes obscenities), or repetitive phrases (in some cases with increasing rapidity). In simpler terms, vocal tics are any tics that involve the larynx, tongue, throat sinuses or mouth.

When both motor and vocal tics are present and persist for more than one year, a diagnosis of Tourette's syndrome (TS) is likely. A number of other disorders often occur along with tic symptoms. For example, conditions associated with TS include attention-deficit hyperactivity disorder (ADHD/ADD), obsessive-compulsive behavior, and learning disabilities.