'Knees' in the Bible

And it was so, that when Solomon had made an end of praying all this prayer and supplication unto the LORD, he arose from before the altar of the LORD, from kneeling on his knees with his hands spread up to heaven.

So Ahab went up to eat and to drink. And Elijah went up to the top of Carmel; and he cast himself down upon the earth, and put his face between his knees,

Yet I have left me seven thousand in Israel, all the knees which have not bowed unto Baal, and every mouth which hath not kissed him.