Forget your anatomy for artists, Art has the upper hand.
Drawings are most meaningful when they disagree with theory because accuracy is not be art despite being very useful.
Head/body ratio is larger in children,
Mother and son have had their head drawn at approx. same size.
Beware of the dangerous facial proportions rules ("drawing exactitude is never truth") because size of ear, nose and mouth are more dependent on head orientation, than on human anatomy.
On the Fabric of Human Body (Andreas Vesalius makes no bones about osteology).
The average human has about one testicle and one breast.
A fugitive model from the law of averages. Forget science : Art has the upper hand. Useful artistic Anatomy should be kept simple. Drawing turns this symbolism on its head.