Animators have to apply some real world knowledge of anatomy to their character designs, or else viewers will be bothered by the totally unnatural way which the characters move.
Characters like Mickey Mouse and Goofy might look more humanistic, but they still retain elements of their animalistic anatomy, such as elongated skulls and metatarsals.
Korean artist Hyungkoo Lee revealed what lies beneath all that cartoon skin and muscle in his series of sculptures entitled “Animatus”, and dem bones look pretty good before they're broken into a million pieces by a falling anvil!
-Via IFL Science!