They are able to bypass this issue by using very rapid jaw movement to project the tongue forward. Present in all frogs are the two mandibular muscles that are used to control the jaw and, therefore, tongue projection. The m. genioglossus is used to protract the tongue and the m.hyoglossus is the tongue retractor. Both of these muscles have longitudinally oriented fibers, which is in contrast to the spiral oriented fibers of the chameleon. Application in humans In human, ballistic movements involve spontaneous propulsion of the limbs. This can be seen in daily routines such as reach and strike reactions, which are atomic by nature. Pointing gestures and placing an object are reach reactions; they have low acceleration and deceleration. On the other hand, punching and throwing are strike reactions; they are characterized by high acceleration and deceleration. These movements have highly variable target locations, and they are referred to as “ballistic” in kinesiology. During ballistic movement an initial impulse is needed to accelerate the limb (hand/foot) toward the target, then a decelerating impulse act as a brake to stop the movement. These movements are characterized by a bell-shaped velocity profile. The Bayesian Model(see Bayesian network), which was developed to perform recognition without pose-tracking, explains human ballistic movement as a sequence of movements between objects and the environment. Each movement is independent from precedent and subsequent one, in varying context. Fast single joints movement in humans is controlled by a series of activation of agonist, antagonist and then agonist muscles; this process is called triphasic activation. Those movements are executed “with a pattern of bursts in the agonist and antagonist muscles of fairly constant duration but different amplitude…” (Acornero et al. 1984). Any ballistic movement involving two joints will require an agonist and an antagonist burst; this can be viewed as the building blocks for different types of ballistic movements. References Muscular system