General terms:
* Internal framework: This is the most general, but accurate, option.
* Structural support: This emphasizes the function of the cytoskeleton.
* Cell scaffolding: This focuses on the analogy of the cytoskeleton providing a framework.
More specific terms:
* Microtubule network: If you're specifically discussing microtubules, which are a major component of the cytoskeleton.
* Actin filament system: If you're specifically discussing actin filaments, another major component.
* Intermediate filament network: If you're specifically discussing intermediate filaments.
The best word will depend on the specific context and the point you're trying to make.