How is "the innermost child" framed in psychology? In art and literature, the adults are usually depicted as having a trapped child in their hearts:



The child is pure and naive, but is trapped in the adult body who is struggling to survive. I think this would simply be called as repression, and maybe in extreme case it can lead to dissociative identity disorder? I think to give a satisfactory answer literature studies should also be included.
What you are talking about is mentioned in psychology to be the “inner child”.

Inner Child Therapy is used within many different forms of therapy.  The inner child is often characterized as a subpersonality within the framework of psychosynthesis or may also be seen as a central element surrounded by subpersonalities. Virtually every talk therapy approach acknowledges and ascribes some meaning to the inner child, but in some cases they use a different label.  Internal Family Systems Therapy (IFS) has expanded the concept considerably in recognizing that there isn't just one inner child subpersonality, but many.


  Inner child therapy has been designed to help those who, as children, have been hurt by the adults and circumstances around them. They may have been hurt, not just by major, easily recognised traumas such as physical or sexual abuse or death of, or abandonment by, a parent, but also by the daily drip drip traumas such as neglect, rejection, criticism, humiliation, bullying, denial or confusion. (Christopher, 2016)


References

Christopher, J. (2016). Inner child therapy [Online]Retreived from: https://www.counselling-directory.org.uk/counsellor-articles/inner-child-therapy