The frontalis muscle is responsible for elevating the eyebrows, while the corrugator supercilii, orbicularis oculi, and procerus play a role in its depression. The function of the forehead is often spared in middle cerebral artery strokes.
The process of dissolving is endothermic when less energy is released when water molecules “bond” to the solute than is used to pull the solute apart. Because less energy is released than is used, the molecules of the solution move more slowly, making the temperature decrease.