Physiology
Muscle contraction
ThePower and energetics
Elastic storage of energy
Ballistic movements are often powered throughPossible benefits
Ballistic systems are capable of power outputs that are significantly greater than that of the muscles associated with the actual movement. One prime example of this is tongue projection in salamanders. This decoupling of muscle work from body/limb work is a major benefit of elastic energy storage mechanisms. Another benefit resulting from this decoupling is decreased thermal dependence of ballistic movement. Deban and Lappin analyzed the prey capture behavior of toads (Bufo terrestris), which involves two types of movement: elastically powered, ballistic movement (mouth opening and tongue projection) and muscle-powered movement (tongue retraction and mouth closing). The toad feeding was observed across a range of temperatures (11–35 °C), and the kinematic, dynamic, and electromyographic variables were measured and analyzed. Over the 11–35 °C temperature range, the ballistic movements had Q10 values very close to 1 (Q10 = 0.99–1.25), signifying thermal independence and supporting the main hypothesis. The muscle-powered movements had a higher temperature coefficient (Q10 = 1.77–2.26), signifying thermal dependence. Another example of a thermally independent ballistic movement is tongue projection in chameleons. It was discovered that veiled chameleons (Chamaeleo calyptratus) were able to perform this high-performance tongue projection, and successful prey capture, across a wide range of temperatures (15 °C–35 °C). Anderson and Deban also found a contrast between thermal dependence of tongue projection and retraction (which is not elastically-powered). This further supports the hypothesis that the elastic recoil mechanism is responsible for the decreased thermal dependence of ballistic tongue projection.Examples
Trap-jaw ants
In trap-jaw ants ( Odontomachus bauri) ballistic movement can be seen in their extremely rapid mandible strikes. The trap-jaw ants mandible has an average closing speed of 38.4 m/s and can produce forces that are 371-504 times the weight of the ant. The ants use these extremely powerful mandible strikes in several novel ways. When the ant attacks a larger animal it will strike the animal and at the same time use the force from the strike to propel itself away from the animal. When facing prey of similar size such as another ant the strike actually results in both animals being propelled away from each other. When the ant is trying to flee from a predator it will strike at the substrate and propel itself vertically into the air.Crickets
In crickets ( Acheta domesticus) ballistic movements can be seen in the way they jump. The kicks that propel the cricket occur over a period of only 2-6ms, but during the 18-40ms prior to the kick the potential energy required is built up by the co-contraction of the antagonistic extensor and flexor tibiae. The crickets can also use these same ballistic movements for swimming.Cone snail
In the cone snail ( Conus catus) ballistic movement can be seen in the way that it fires is harpoon-like radular tooth into its prey. After the cone snail’s proboscis comes in contact with its prey the tooth is ejected 240-295 ms later. It is believed that the propulsion of the tooth is accomplished by pressurizing the fluid space behind the tooth.Salamanders, toads, and chameleons
In Salamanders, Toads, and Chameleons ballistic movement can be seen in their tongue projection which is controlled by an elastic recoil mechanism. The orientation of the muscle fibers is significant because it is what allows ballistic movements to be possible. In chameleons, the muscle fibers used for ballistic tongue movements were found to be in a spiral orientation, with an equal amount of fibers oriented clockwise and anti-clockwise to prevent torsional movement of the tongue during projection. The internal fiber angles are approximately 45 degrees, which is the theoretical optimum to create an equal strain throughout the accelerator muscles. In salamanders of the genus Hydromantes, the pattern of muscle activation has been mapped. The main muscles used for ballistic tongue movements in these salamanders are the subarcualis rectus (SAR) muscles. These SAR muscles can be further divided into anterior (SARA) and posterior (SARP). The first muscle to be activated is the SARA, which is located near the back of the head. The SARA remains active until the tongue makes contact with the prey. Next, the posterior SARP, located further back on the medial and lateral sides of the salamander is activated. Then the middle SARP is activated and the anterior SARP is the last to be activated. The time between activation shortens and duration of activation increases with increasing prey distance. Ballistic tongues have evolved two times previously in the Hemidactyliini and Bolitoglossini genera. The exact mechanisms of tongue projection vary slightly throughout the taxa, but the resulting projections have remained relatively constant. Frogs do not have a specialized muscular structure for tongue projection. 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” inReferences
{{reflist Muscular system