I don’t know the exact location, but I think just know the Mana Indriya located in the brain is enough. Careful when going too deep into these kind of “spiritual” subjects, it may veer you away from the Path to Nibbana.
Better take the precious time to contemplate on the Dhamma itself. The Buddha was said (according to Thanissaro Bhikkhu) “Every morning, looking at the rising sun, think about it as if this is your last morning, what you will do?”. There is so much of the Path to practice and contemplate, start from the very basic levels toward the realization of Nibbana (Dana, Sila, Sagga, Adinava, Nekkhamma and Cattari Ariya Saccani at the end of the gradual training process).
This is the first time I see you in this forum, may you attain Arahant stage in this very life. This is totally possible.