The Chakra systems were developed over a thousand years after the Buddha taught by tantric yogis.
There are many Chakra systems, with different locations and different number of Chakra.
The theory of the subtle body and its energy centers called cakras (or padmas, ādhāras, lakṣyas, etc.) comes from the tradition of Tantrik Yoga, which flourished from 600-1300 CE, and is still alive today. In mature Tantrik Yoga (after the year 900 or so), every one of the many branches of the tradition articulated a different chakra system, and some branches articulated more than one. Five-chakra systems, six-chakra systems, seven, nine, ten, fifteen, twenty-one, twenty-eight and more chakras are taught, depending on what text you’re looking at. The seven- (or, technically, 6 + 1) chakra system that Western yogis know about is just one of many, and it became dominant around the 16th century (see point #4 below).
Also another important point is the following
2. THE CHAKRA SYSTEMS ARE PRESCRIPTIVE, NOT DESCRIPTIVE.
This might be the most important point. English sources tend to present the chakra system as an existential fact, using descriptive language (like ‘the mūlādhāra chakra is at the base of the spine. it has four petals,’ and so on). But in most of the original Sanskrit sources, we are not being taught about the way things are, we are being given a specific yogic practice: we are to visualize a subtle object made of colored light, shaped like a lotus or a spinning wheel, at a specific point in the body, and then activate mantric syllables in it, for a specific purpose. When you understand this, point #1 above makes more sense. The texts are prescriptive — they tell what you ought to do to achieve a specific goal by mystical means. When the literal Sanskrit reads, in its elliptical fashion, ‘Four-petaled lotus at the base of the body’ we are supposed to understand ‘The yogī ought to visualize a four-petaled lotus…’ See point #5 for more on this.
Read more here http://www.tantrikstudies.org/blog/2016 ... he-chakras
So basically the short answer to your questions is that there is just no answer, since Chakra is alien to early Buddhism (but was adopted later by Vajrayana) and there are just as many chakra systems as there are yoga systems.
Vayadhammā saṅkhārā appamādena sampādethā — All things decay and disappoint, it is through vigilance that you succeed — Mahāparinibbāna Sutta
Tārakā timiraṃ dīpo māyāvaśyāya budbudaḥ supinaṃ vidyud abhraṃ ca evaṃ draṣṭavya saṃskṛtam — A shooting star, a clouding of the sight, a lamp, An illusion, a drop of dew, a bubble, A dream, a lightning’s flash, a thunder cloud — This is the way one should see the conditioned — Vajracchedikā Prajñāpāramitā
I have seen all things that are done under the sun, and behold, all is vanity and a chase after wind — Ecclesiastes 1.14