Karna was born to Kunti and a sun god. His unparalleled skills as a warrior earned him the friendship of Duryodhana (the eldest of the Kauravas) and made him the king of Angadesh. In order to save the Pandavas, who were related to Karna by his mother's lineage, Lord Krishna exploited Karna's big heart. He stripped him of all his armor and the boons that made him invincible -- which Karna gave willingly because he was so generous. Thus, the Pandavas won the battle. Karna also refused Krishna's offer to ascend the throne and take what was rightfully his, as the eldest of all the Pandavas.
In yoga, karnapidasana is a posture that requires a fair amount of flexibility. To enter the asana, the practitioner assumes halasana, or plow pose. But rather than extending the legs, they are bent so that the knees rest on the floor beside the ears.