Respuesta :
Bone and limb formation is controlled by the mechanisms of the embryonic development. There is a specific group of genes, called the HOX genes that code for proteins that are transcription factors which precisely control the formation of body segments
All motions must start with an impulse from the brain.
The brain then sends those messages or impulses throughout the body. Once the different parts of the body receive those impulses, in this case the muscles, they contract and perform the action requested by the brain.