It is obvious that more things may be carried with a pole across the shoulder than on the head or on the shoulder. This also explains deep philosophy. The pole that Idumpan used was a bamboo with seven nodes or joints. These denote the six aathaarams ( ie bases or abodes ) in the human body and the brahmarantharam. These are named moolatharam at the anal region, suvaathishtaanam at the navel, maNipooraham at the abdomen, anaahatham at the chest region, visutthi at the neck, aaknjai between eye-brows and the brahmarantharam at the crown of the head. Of these, moolathaaram is the abode of the kuNdalini sakti. This is the Saktigiri. Brahmarantharam is the abode of Siva and is therefore Sivagiri. Idumpan who, with the help of Sage Agastya’s upathaesam, had connected these two through the spine, saw in the crown of his head the ever Beautiful Murukan. Anyone can see Him with devotion and the upathaesam of a true guru. This is the truth enpounded by the carrying of the kaavadi.
By Dr. Devapoopathy Nadarajah, from the book titled The worship of Murukan (2011)