lying still atop the bed of serpent which has five heads and mouths —

on the serpent bed (where the serpent-s hoods are expanded due to coming in contact with emperumān) —

on top of the mattress of thiruvananthāzhwān (ādhiṣĕshan) —

atop ādhiṣĕshan —

emperumān who is lying on the mattress of ādhiṣĕshan with thousand hoods —