Cyanide Blocks Cytochrome 4

Methylene blue works on all of the cytochromes. The most important one, this is where I am a bit confused because I know it can work on cyochrome for which is cyochromesiaoxidase. But which I think is blocked, that is what is blocked with cyanide. There is roton-known that can block cyochrome one and methanol-luis seems to be there,. but I am wondering in excluding these pathologic conditions where there is this impairment due to some metabolic challenge in normal conditions, where is methylene blue working?