In everyday life we use our anatomical body parts to do some functions and on the basis of those functions some have been assigned as cultural and spiritual significance. For example our brain is associated with mind which is not a anatomical part but a spiritual part of human body , similarly heart is also associated with emotions which directly affect the muscles function like fear , dare and coward so heart is associated with most of emotions but muscle is associated with emotions which require action .
Devils and demons are often described as having characters of an animal that is they have big nails , big horns , tails , big teeth and their skin is often rough and rugged.