I find your site useful to refer students to.

This is similar to how I teach the figure, but more anatomically accurate is the 8 1/2 head rule. The head points don't exactly correspond so perfectly/coincidentally with the real figure, but it is much more natural looking outcome. for eg. the spine is the same length as the femur (the longest bone in the body). The neck is about 1/3 of a head, with the arm-pit being about 4/5ths of a head below the chin. The extra 1/2 head balances the 3-head width of the shoulders to look less neanderthal. Out of interest I also teach a 9 1/2 head rule for fashion students.