If your palm is facing down to the ground then usually the radius bone will break and the bit nearest your wrist will be pushed upwards.
Can you break your wrist by hitting it. This is called a Colles fracture named after Dr Colles who first described it. Lets simplify your golf swing wrist hinge and take the perfect backswing. Probably the most brutal way.
You need hand wraps and sparring gloves of 14oz to punch the bag. Or go to the doctor for an X-ray. The wrist is made up of eight small bones which connect with the two long forearm bones called the radius and ulna.
They can also occur when your wrist twists severely or. Occasionally you can break your upper arm because you have developed a type of cancer. If you are elderly it is possible you have developed thinning of the bones osteoporosis.
If you want to actually break your wrist the best way is the following. This is called a distal radius fracture by hand surgeons. Then make sure the hammer you are using is not a sledge.
If you break your hand its important to seek medical attention right away because a broken hand can cause a lifelong disability. If you need accuracy more than distance theoretically you should cock your wrists less. Some veins are tied down in such a way that trauma will crack them open.
Without you hit the bag at an angle thats dangerous to these bones -- so dangerous that a particular kind of hand fracture is called a boxers break If you feel sharp pain in the bones of your hand stop punching immediately and check with your trainer or doctor. By simply manipulating the roll in your wrist in the downswing. You can help prevent these injuries by wearing hand wraps.