Answer :
our elbow bends all the time, we bend it when we pick up things, when we eat, when we do mostly everything. Cows on the other hand dont pick up food with there feet, they use there mouths, and they probably only bend when they are walking.
The elbow joint of the cow and the elbow joint of the human are a pair of homologous organs. Homologous organs can be defined as the traits that are inherited by two different organisms from a common ancestor. The structure of these organs are similar in both organisms but their function is different.
The connecting bones of the elbow joint in the humans and the cows are the same, but the radius and ulna of the cow are fused together. In cows, the elbow joint helps them to walk while in humans, the elbow joint helps to lift and carry.