The stratum corneum is the outermost layer of epidermis, which is mainly composed of 5 to 10 layers of flat dead cells without nucleus. When these cells fall off, the cells located in the basal layer will be pushed upward to form a new stratum corneum. If you bleed, the stratum corneum will be broken, but the area will not be too large, and a new stratum corneum will be formed, so it will not cause the stratum corneum to become thinner.