thanks

A shaft or a ray of light

Hello zhanghongxiang. Nice to meet you. . a "Spearhead" refers to a shaft of light, (or lighter color). So far as I can tell, since this refers to the two bones in the lower half of the human arm and the space (or valley) between them, it does mean a Lighter Color. Unless it means that the tissue is broken, separated, and there is a complete open space through which light can now pass.---Warm Regards, Bruce