Certain members of my immediate family have expressed a weary tolerance for my wondering about words. This being the case I will likely continue to ponder such deep issues as: Why is the Latin name for the common house mouse a rather macho sounding Mus musculus?
This one goes back a ways. Evidently the ancient Greeks, trendsetters that they were in medical matters, noted that the muscles of the upper arm kind of looked like mice.
As a result the Greek word mys means both mouse and muscle. The latter sense comes down to us today as the prefix myo meaning muscle. Inflammatory conditions of muscle tissue are therefor myositis.
The Romans did a lot more borrowing than innovating, so in similar fashion mus is mouse and musculus, although it literally is "little mouse" in Latin, has come down to us as muscle.
Somebody in the depths of Middle English must have been having a little fun when they coined the term lacertous as a synonym for muscular. It means "lizardy" but it seems to me that Medieval England had a lot more mice than lizards.