Thankfully I have never suffered any major injury from training.  When I was in my first tournament, I was in TDK at the time, I took a kick to the face where I was seeing stars for a few days.  That was probably a concussion though I was never treated for it.  Other than that, no injuries, so I consider myself fortunate.  I've never seen anyone get really injured in class, but in tournaments I've seen people get knocked out and carried out to an ambulance.  There was a TKD tournament I was coaching in where a student turned, hit the opponent in the face with an elbow, breaking his nose, and blood flooded out all over his white Gi and onto the mats.  His nose was smashed, the bloodiest injury I have seen first hand.  Not a match I was coaching, but still. 

Likewise, I have never suffered a serious injury from training. I have been very lucky. However, the worst injury I have received was during my black belt test. We were in the sparring portion and my sensei and I were doing Kyokushin style fighting. He got a really nice punch right to my sternum and I ended up with a contusion. I couldn't lift my arms above my shoulders without pain for a week! My sensei asked if we needed to stop after he had delivered the punch, but he also told me that if I stopped the test at any point that I would fail it so I kept on going. He told me later that if I had stopped at that point for a small break that I wouldn't have failed and apologized for hitting so hard. Mistakes happen! Still, I got my shodan and it's a good story so many years later.

During my JBB training I accidentally stabbed myself in my right knee with one of my Kama’s.

How??

Moved my right foot forward instead of my left foot. 

 

Worst ever was a severely sprained thumb from catching a hard kick directly on it instead of the forearm/wrist area like a block was supposed to be done. Misjudged distance and timing during drill. Took dam near 3 months before the pain/sensitivity got back to normal. 

Worst ever seen was a senior student nearly take his ear off with a kama that wasn’t all that sharp

Eww, not a good sight.

The dumbest thing I managed to do was dislocate my small toe on my right foot, courtesy of the person to my right and their pant leg. I can't remember if I was getting up or down, but my toe for whatever reason snagged their pants and dislocated my toe. 

Otherwise I've had no other injuries because of my training.

I have dislocated my right knee several times in martial arts training. The first time I dislocated it, I was just walking in a straight line down a hallway at school, which should have been a clue that I had something wrong with my joints, but I didn't get a diagnosis about that for about 15 years. The first time I dislocated it in martial arts training, I was working with a throwing dummy in my Judo class, and I was told to work on drop seoi-nage, which resulted in the dummy slamming into the side of my dropped knee. The second time, I was throwing slip kicks on a pad, and my foot slid on the sweaty mat. The third time was attempting a foot sweep at the wrong time when their leg was fully based.

To all of you that have shared your MA injuries…OUCHY!! I feel your pain!! Glad you all survived your injury/injuries.

I broke my left ring finger on my green belt (rokkyu) test when I snagged my finger on my CI's pants leg while blocking one of his kicks - that took a month or two to heal. I also jammed my right thumb at a black belt training session when I tried redirecting a partner's kick and didn't tuck my thumb in properly.  That was sore for a month or two as well.  Also, in my very first seminar with Master Thompson, I was doing ashikitae with my CI's younger brother, and kicked him in his forearm.  I got a bone bruise that lasted about 2-3 months.

Nothing that made me really stop training, but I had to adjust my training to deal with those injuries.