serratus posterior inferior

As far as I can tell, that its name. Its a muscle in your back. Unless you lifted 6,000 buckets of cement yesterday, you probably don't even know it exists. I did, and I do. My serratus posterior inferior is a bit angry with me today. He's like, "Dude! What was all that about?" You see, my SPI has grown quite accustomed to a sedimentary lifestyle of stretching slightly during basketball games and leaving pretty much every other activity to the other muscles of the torso. Yesterday, he was put to use. Matt and Lisa are adding a two-story addition to their house. I helped Matt and a bunch of other people pour the floor for the second story. We did it by filling buckets, passing them up and dumping them. We worked with incredible efficiancy and had it finished by noon, even with a late-arriving cement truck (big surprise).