Reported first on the Sports Cartel network site Back in Blue, St. Louis Blues left wing Keith Tkachuk will be sidelined indefinitely with three fractured ribs.

What is a fractured rib?

A rib fracture is a crack or break in one of the bones of the rib cage.  The most common cause of a fractured rib is a direct blow to chest - and in Tkachuk's case, it occurred when the blade of his hockey stick got stuck in the pads of a goaltender, jamming the butt-end of the stick into his chest.

Ribs can also be fractured with forceful coughing, most commonly occurring in people with a disease like osteoporosis or when cancer has weakened the bones.

Gilbert Brule of the Columbus Blue Jackets has a broken sternum. Can you say ouch? I know you could.

For those who slept through biology or anatomy class, your sternum is the bone that holds the rib cage together. It's the framework for protecting your lungs. By breaking or fracturing your sternum, you are putting your lungs at risk.

Why is a sternum injury so painful? The sternum helps with your breathing, so each breath causes more pain. This is especially true when breathing is labored or deep.

How do broken sternums happen? Blunt force trauma is always the cause. In this case, Brule was checked in the chest. The compression caused the sternum to break. Almost all sternum injuries end up with pieces of the sternum fractured. It's not a clean break. In most cases you're going to need surgery to pin the pieces together.

A fractured orbital bone, a result of a puck to the face of Toronto Maple Leafs forward Mats Sundin, may have the Toronto captain sidelined for at least four to six weeks -- and possibly more if surgery is required.

"I can go back to when I was on the ice when Bryan Berard's eye injury happened to him - it's certainly something you don't want anyone to go through," said Sundin.