1 :an abnormal pouch<span> or sac opening from a </span>hollow organ<span> (as the colon or bladder)
2 :a blind tube or sac </span>branching<span> off from a cavity or canal of the body. the liver is an anterior diverticulum of the intestine.</span>
I'm not sure, but I think that its your skin that protects the internal tissues.
Muscular strength is how much you can lift/push/pull, ect. Muscular endurance is how long you can do something with your muscles. Like if you have to put your are straight out in front of you and hold a 25 pound dumbbell. Your will get tired and give out. the more Muscular endurance you have the longer you can do something with your muscles.