As the colourful image explicitly demonstrates, each component has its own individual identity and purpose...however, it exists within a larger framework. Although each has its own intrinsic operation and purpose, it essentially serves the larger whole. This is likely intuitive to most, however this intuition seems to be put aside as soon as a therapeutic or rehabilitative context is in play.
Although exponentially more complex, the developmental process can be thought of as a very sophisticated and comprehensive hierarchy.
The most basic and fundamental elements of any human organism (for the simple sake of survivial) are the vital functions. Without coherent establishment of the systems that sustain life, any other consideration(s) are irrelevant. Further, proper functioning (or interaction) of the human organism within the environment REQUIRES that these vital functions be well-established in order to generate productive results.
Mobility and closed-chain can easily be confused and inter-changed within the neurodevelopmental disorder (NDD) context. In more practical terms, it referes to the selective independant mobility (freedom) that exists within each of the diverse segments of the body. This includes ALL of the traditional "joint-like" articulations as well as the equally important fascia larticulations within the body. Therefore, the term "mobility" is used, not to define movement as such, rather to describe some level of intrinsic elasticity and adjustment to positional changes. If we extend this description further, we arrive at the term "closed-chain"...which can understandibly refer to a vast number of specific movements and dynamic activity. But, once again, when we consider the NDD context, a closed chain activity refers primarily to postural characterisitics such as independant sitting, balance, and counterbalance. These considerations MUST be addressed and developed before any consideration or focused strategy regarding more dynamic (open-chain) function.