Tongue Mechanics





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The hollow tongue sheathes over a long, tapering cartilaginous spike called the hyoid horn. The horn attaches to the center of the hyoid bone. The tongue consists of three primary components: The sticky tip, the retractor muscles and the accelerator muscles. (musculus accelerator linguae). When at rest, the whole assembly sits at the bottom of the mouth, the base placed down in the throat behind the head. Before striking, the lizard moves it toward the front of the mouth and muscles raise the hyoid bone above the lower jaw. After aiming with the entire head, the chameleon is ready to fire.

The accelerator muscles are essentially sphincters. These rings of muscle squeeze against the hyoid horn. Because the horn tapers toward the tip, the muscles drive the entire tongue out of the mouth. Lubricated cavities between the muscles and the bone reduce friction so the tongue can fly with greater speed. The effect is the same as squeezing a watermelon seed to make it fly, except in this case the seed remains stationary and the sqeezer is propelled into space.

The tip of the tongue resembles a club. Covered with a sticky saliva, it's abrasive surface also grips, High speed photographs of the tongue in flight reveal a flap of skin trailing the head of the club. The flaps wrap partially around the prey on impact. Wet worms or slugs, however frustrate the system because the saliva won't adhere to their slimy surface.

Chameleons also chew their food.

