Wich are the guilty ones?

[flerc]

When my daughter is lying down over the concave side, I see her spine straight, but just she is stand up, the curve appears immediately again. Which is the guilty of this impossibility to keep the spine straight?

_Muscles
_ligaments?
_Tendons?
_Vertbras
_Discs
_Rib cage?
_Joints
_Internal organs
_Fascias
_Something else?

Saying in other words, if it would be possible to improve without limits only one of these body parts, which of them you’ll select?
May be a combination of all, but I can not believe that percentages of incidence could be the same for all. Could it be different for everyone?

One surgeon said me that vertebras (and probably she said discs too) are the guiltys without any doubt, another surgeon said me that muscles, other said me 80% muscles 20% joints, internal organs are the guilty for some western therapists. Surely Abr people thinks that it is the pneumatic skeleton.
This week I was thinking ABR people are right. Last week I thought the first surgeon was right, Last month I thought second surgeon was right.. I don’t know what I’ll think tomorrow. Now, I'm thinking about muscles again, but not because strength, as some months ago, but because length. I think that is not a mater of short length in the convex side, as I heard, but it is because muscles of the concave side are much longer.. Or may be because ligaments?
What do you think? Every kind of answer seem to be so reasonable as any other.