Foot Anatomy 101-The Special Skin on Your Feet

In this third post in the Foot Anatomy 101 series I’d like to discuss the unique “feetures” of the skin on your feet. Since so much about the feet are are unlike other parts of the body, it will probably not surprise you at this point to learn that the skin on your feet is also unique, being especially adapted to the demands of walking and running. Here are some of the special features of ‘foot skin’:

• Prints. The skin on the sole of your foot possesses prints. Only the palms of the hands and the soles of the feet possess these tiny undulating folds. The pattern of skin prints on the hands and feet are wholly unique for each person – even genetically-identical twins have unique fingerprints and footprints. Your skin prints are also immutible, meaning they do not change over time. For these reasons fingerprints and footprints can be used for identification. But why do we have these prints on our hands and feet? Answer: To improve grip. The prints on your hands help you to grab and hold objects; the prints on your feet increase traction for walking and running. Like the tread on a car tire, those skin folds augment friction to better enable us to grasp the ground and reduce slipping. Unlike car tires which go ‘bald’ and must be replaced, our skin is self-replenishing, prints and all. Of course, our skin prints are rather useless inside a shoe and many shoe soles are smooth and extrememly slippery by comparison, especially under wet conditions.

• Innervation. The soles of your feet are one of the most nerve-rich parts of your body. The three most highly innervated parts of your body are your hands, your face (particulary the lips) and your feet. Why the feet? The feet (when bare) are the only part of your body that is in constant contact with your environment. With over 100,000 nerve endings per foot, tactile feedback from the soles of your feet provide a wealth of information to your brain about the ground upon which you tread. Whether you are walking or running, that information is used to make adjustments (within milliseconds) to your gait, the goal always being to reduce impact forces on your joints and body. Of course, this information is also used to warn you of dangerous terrain or injurous objects. Unfortunately, most footwear creates a ‘shoe-induced neuropathy’ because the thick outersole and cushioned innersole eliminate sensory feedback.

• Sweat Glands. The soles of your feet have a tremendous number of sweat glands. In fact, the three ‘sweatiest’ parts of your body are your scalp, your hands and your feet. Although rich in sweat glands, these parts of your body rarely sweat enough to produce dripping sweat; that only occurs under extremely hot conditions or during vigorous exercise. Usually those sweat glands are producing micro-droplets of sweat that quickly evaporate and remove heat from the body. Of course our hands and head are almost always bare and we cover them only under extreme conditions, but our feet are regularly locked away in both shoes and socks. The sweat and heat are thus trapped and the dark, moist, warm, stale conditions inside a shoe become a breeding ground for bacteria and fungi. Shoes are the basic cause of athlete’s foot and the best way to avoid or even cure athlete’s foot is to go barefoot as much as possible. Enclosing the feet in shoes and socks may also lead to difficulty in regulating body temperature, a condition I call ‘hot foot syndrome.’

• Attachment. The skin of the sole of the foot is attached to your body exceptionally tightly. The skin on the palms of the hands are similarly attached. You can easily demonstrate this on your hands and feet by pinching the skin. On the top of the foot (and hand) the skin is attached rather loosely to allow flexibility; the skin there can be pinched up and moved about readily. By contrast, the skin of the sole of the foot (and palm of hand) is attached firmly and cannot be easily pinched up or moved side-to-side. This feature increases the skin’s resistance to the high sheer forces experienced when walking and running.

These are just four ways the skin on your foot differs from skin on other parts of your body. There are other differences, too, but these four illustrate the point that the feet are remarkably designed for their functions – standing, walking and running. The skin works best when the foot is bare and kept bare as much as possible. Constantly wearing shoes weakens and softens the skin, making our feet tender and prone to injury. The lack of proper ventilation in closed shoes and socks keeps the skin moist and makes it more vulnerable to invasion by microbes and infection while simultaneously creating the perfect environment for such microorganisms to grow. Going barefoot is healthy for your skin. Callouses and blisters are frequently caused by shoes but rarely result from walking barefoot. With plenty of exposure to sun and air, the skin on your feet will become healthy, strong and beautiful.