it is one this, there resides 'Aagnya Chakram' of Kundalini yoga. It is in 'Puruva Maddhi' or between the eye brows. Maditating on this part is belived to give omplete control over once mind.
to my knowledge there are two types of Kunadlini.. one which is talked about by our sidhdhars and the other which is talked about by vallalar and aurobindo ghosh...
the first one talked by sidhdhars is situated in moolaadhaaram and by practice it has to be moved from the bottom to each chakram step by step where the kundalini will stay for some time before moving up...
the second as told by vallalar and aurobindo is kundaini which is on top of the head.. yes it is said that there is a kundalinin which is on top of the head
vallalar talks extensively about this in "tiruvarutpa".. he says that the kundalini will come from above and land in puruvamadhdhi.. then it will go down in the front part of the body to the moolaadhaaram and again will rise through the spinal cord.. it will not stay anywhere
aurobindo ghosh also talks about this only and not the sidhdhar's kundalini.....
"valluvar karpam 300" a book supposed to be written by tiruvalluvar also talks about this..
Sidhdhar's exactly talk about the same kundalini as told by lalitha sahasranamam or the ancient one...
but aurobindo ghosh and vallalar differ on that...but inspite of talking about "aayiram idhazh thamaraipoo' on the head they still maintain that the kundalini energy drops from above the thamraipoo.... and they say that they have experienced it..
he says that kundalini is there in "niraadhaara" state.. which is quite differen from what sidhdhar's say....
and vallalar goes on to reiterate that the kundalini shakti which he talks about can be easily obtained just by jeevakarunyam....by avoiding no veg and other things....
it might be "chitkundalini" or any other type of kundalini..
a book called "Vignana bhairavam" also talks extensively about "chitkundalini"
tiruvalluvar also says that jeevakarunyam is the key