指甲同牙齿与骨头都是人体最坚硬的部分。指甲具有保护脆弱的、布满神经的指尖免于损伤的功能,同时有助于增加指尖的触觉与对小物体的控制。正常的指甲,由于指甲下皮层内布满毛细血管,血液供应充分而呈桃红色。指甲包含有10％的水份。手指一星期平均生长0.5—1.2毫米,大约是脚指生长速度的四倍。手指越长,指甲生长的速度越快。较高的温度有利于加速指甲生长。这样,夏天指甲的 Nails with teeth and bones are the hardest part of the body. Nails have the function of protecting fragile, nerve-filled fingertips from damage while helping to increase finger touch and control of small objects. Normal nails, due to nail capillaries covered with capillaries, the blood supply is full and pink. Nail contains 10% water. An average finger growth of 0.5-1.2 mm a week, about four times the growth rate of the fingers. The longer your finger, the faster your fingernails grow. Higher temperatures help speed nail growth. In this way, summer nails