11.   Once the brain receives an arousal signal, it sends a message to the penis, which causes tiny muscles to relax.

12.   The muscle relaxed, and I resumed my pace gingerly.

13.   The researchers determined that rapid uptake of calcium ions is what allows the tail-tip muscles to quickly relax in preparation for the next contraction.

14.   With the Baclofen pump, there is hope that, once his muscles relax, he might be able to breathe normally and not require his oxygen bottle.

15.   My muscles relax and I lean back feeling momentarily at peace with the world.

16.   This causes muscles to relax and allows bronchial tubes to dilate, aiding the flow of air to the lungs.