30 medical students who have rated visibility of 40 brain anatomical structures (each structure has been rated on a Likert scale of 1-5, where 1 corresponds to "not visible" and 5- "clearly visible").

I am trying to figure out what will be the appropriate statistical test in this situation please to figure out the correlation among the ratings of the different students? I am not sure even if "correlation" will be the right test here, any advice for statistical analysis of this data please?

Thank you.