This is not funny. Uncontrollable backhand syndrome (UBS) is a serious medical condition that affects many people (particularly those living with stupid people). It results in severe injury to the back of one's hand from repeated impacts with various surfaces. Jk. Excellent effect. Very realistic and painful to look at.
Your work is lovely! But I hope you wont mind a few suggestions for better realism? The bones in the hand need to be just a little wider, and the area around the edges of the wound need to be a brighter more irritated red. The damaged area of the flesh looks strange to me. Might I ask what type of wound you intended? I may be able to give you some insight on certain types of wounds, having experienced some rather nasty first hand damage myself. Though you are quite free to disregard me entirely. @_~
These are not the bones, they are the tendons. At least, I am not the artist, but as you can see in the image, only the skin came off, and the next layer would be the tendons. You'd need to take those off too before seeing the bones.
Oh, suck it up you big baby! Ugh. Men are such bad patients when it comes to pain, huh? Just kidding, you've done a wonderful job! That actually looks extremely painful. But seriously, just sleep it off. It'll be fine in the morning.