It is not necessary to investigate as far as possible – as I did – on the ba­sis of x-rays of the human structure. Four points of anatomical ge­om­e­try will suffice to suggest that both the possible rotations of the arms aro­und the shoulders and the legs pivoted on the pelvis identify four circles in­de­pen­dent of the navel, two by two symmetrical but dif­fer­ent­ly di­ver­ging from the central axes of the body.
They may be located at mo­re or less unequal distances, according to va­rio­us ra­di­o­log­i­cal sam­ples or qualified schemes, but it is the cir­cum­fer­ence that must be adapt­ed to these, and not the other way around.
In other words are the virtual circle arcs de­scribed by the phys­io­log­i­cal­ly pos­si­ble ro­ta­tions of the limbs, to de­lim­it the max­i­mum ex­ten­sion of the en­tire hu­man body in ev­ery di­rec­tion; and this is what must be con­tained by the cir­cum­fer­ence in­tro­duced by Vi­tru­vius
In a basic scheme, we are fac­ing two arcs cen­tered on the hips, whose ra­di­us is de­ter­mined by, and is evenly car­ry­ing the stand­ing po­si­tion lenght of the legs, not with the ex­tend­ed feet;
even if they overstep im­me­di­ate­ly the giv­en cir­cum­fer­ence, at each leg abduction.