Your personality type is probably ISFJ (or perhaps ISTJ).
If your personality type is ISFJ then you are interested in knowledge and experience, particularly in relation to family, friends and colleagues. You are a quiet, serious observer of people, listening intently and getting to know a great deal about them. You pay attention to their emotions and feelings, and are keenly aware of the state of relationships between them and you take your responsibilities to them very seriously.
If your personality type is ISTJ then you are interested in clarity and knowledge. You like to observe and listen, and have a particular interest in facts and information which help you to develop as clear a knowledge as possible. You like to know where you stand, e.g.: having clear goals to which you are working, and to know that what you are expected to do is achievable. You value your experience, which serves as a strong guide to your decisions.
Your mental muscle diagram suggests:
* your dominant function is Sensation and very introverted
* your auxiliary (second most important) is Feeling and very introverted
* your tertiary (third) is Thinking and very introverted
* your inferior (fourth) is iNtuition and very introverted