Not sure what to see in the 1st photo so no opinion on it. The 2nd photo, my opinion is it is a scratch stretching left to right. The reason I say that is at the left end, it appears that a two "features" on the left merge at a very shallow angle, which I interpret as a short scratch merging into a longer scratch. But if you think they are cracks I would not suggest not using it; from what I hear a breaking a crankarm can lead to a serious crash. You could try to find a lab that can do an ultrasonic inspection to see if it is a crack.