Skeletal System
The bear's skeleton looks more like that of a dog. That is why they are related to the dogs, wolves, and foxes. The only difference between the bones of a bear and a dog is the weight. Also, the grizzly's teeth and skull are not as adept as a dog's for biting and shearing. Nonetheless, the grizzly's raw strength more than makes up for that. Although bears have short limbs, the sheer strength of their bones allows for great support.
Muscular System
Advanced muscle systems in the legs allow the bear to run, jump, swim, and climb better than most species. The massive hump in their backs is a muscle that allows the bears to move quicker by building up momentum. Muscles are controlled by connected tendons, much like that of a human. Their muscles also act in pairs (one muscle pulling on another).