Skin sensation
When we cut the skin near the parts of nails of fingers and toes we do not feel pain. Why?
V. BHALAKUMAR
Chennai
The skin consists of two layers — the outer epidermis and the inner dermis. The epidermis contains 5 layers. From bottom to top the layers are named: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.
The bottom layer, the stratum basale, the cells divide and push already formed cells into higher layers. As the cells move into the higher they flatten and eventually die.The top layer of the epidermis, the stratum corneum, is made of dead, flat skin cells that shed about every 2 weeks.
The thickness of the epidermis varies in different types of skin. It is the thinnest on the eyelids at .05 mm and the thickest on the palms and soles at 1.5 mm. Hence removal of outer layer of skin in palm and sole are not painful. The nail folds are no exception.
The skin on the underside of the nail folds sheds constantly as the nail plate grows and rubs (sloughs) against it. These dead skin cells attach to the nail plate and become visible as the nail grows. This attached skin is referred to as the Ptygerium, dead skin cell or the true cuticle. This needs to be removed regularly in order to prevent a build up.
Similarly the external part of hair is made up of dead cells and keratin and hence not painful on removal.
Dr. S. SELVA SEETHA RAMAN
Dept. Of Plastic Surgery
Stanley medical College, Chennai
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