How to model a table in a relational database where all attributes are foreign keys to another table?
Frame challenge: unless this is a toy project not intended for a real-life application I suggest you study existing models that represent healthcare data instead of reinventing the wheel. There are more complexities in this area than you might think. One example would be the HL7 FHIR model, which, incidentally, has multiple open-source server implementations that are ready to be used.
This intro on Coursera might be helpful too.