Between the brain and the heart lies a narrow strait called the neck.
This neck presents a major challenge, because the brain must ponder very deeply to squeeze its thoughts through such tight passage and reach the heart below.
But it is also a great advantage, because when the heart is thrown to and fro by the mighty rapids of life, spinning in circles from the turbulence of desire and fear, the brain can still observe from its perch high above the rapids and direct the heart back on course.

I think the discussion has lost meaning when we ask which part of a human being is more important. In my humble opinion every part of us was created by H' and therefore all parts deserve respect. All of them!. As a person who has had several operations to take out parts that were not helping me anymore, I grasp that, there is a hierarchy of what organs allows to live . Yet, surely. we have assigned more importance to the heart and the brain. How? Only metaphorically, we say that the heart harbors emotions ,and the brain sechel and chochma. The heart, as site of emotions, is an old notion and that is why we marry with a ring in the index finger. Yet, surely it our brain that is control of it all emotions, intelligence, and understanding. As for the neck, it is just a separation necessary to be able to turn around, eat ,and also say No, or Yes, depending in the issue. Actually, the scrutiny of body language permits us to "read" what the person is conveying. It is the whole body