The integumentary system of the upper extremities (including the shoulders, arms, hands and fingers) includes the skin and hair, and nails of the upper extremities. The skin of the hands and arms (especially the hands) is more frequently exposed to sunlight and to environmental toxins than other parts of the body. Therefore, the hands are likely to show evidence of accumulated damage from these influences as a person ages.
Fingernails are located at the upper tip of each finger. They protect the fingertips from injury and also enhance the delicate movement and sensitivity of the fingertips, although the nails themselves have no nerve endings.
The integumentary system is made up of the skin and its appendages (such as the nails and the hair). Its primary function is to protect the body from damage; it is also involved in temperature regulation and in the sense of touch. Upon exposure to sunlight, the integumentary system is also the primary vehicle for synthesis of vitamin D.