to the backbone

[Ivo]

Would you tell me whether I am right with my interpretation of the expression in bold in the following sentences?

He’s a Socialist to the backbone, not only in speech, but in his practical everyday life.

The thought made him flush hot with embarrassment even though chilled to the marrow .

The childish words went through and through his mind, blotting out all coherent thought.

to the backbone = entirely, totally, to the marrow, through and through,

Thanks for your efforts.