Essential Knowledge

Hairdressers learn about the structure of hair, how it grows and where it comes from; beauty therapists learn about the structure of the sin, the underlying muscles and bones and basic workings of the human body. They do this in order to understand the area that is being treated, how to vary treatments for individuals, how to recognise potential problems and how to put right something that has gone wrong. Nail technicians must do the same. They must learn about the area of the human body they deal with. This will ensure that they work safely, understand when and how to adapt treatments, give the best possible advice to their clients and know how to deal with problems.
Areas of the body are not isolated. The body functions because several systems within the human body work together. When one of these systems does not work properly, many areas of the body and other systems are affected. The main 'systems' in the human body are; nervous system; cardiovascular system (heart, lungs and circulation); digestive system; skeletal system; endocrine system (glands); urinary system; and reproductive system. Many organs are concerned with and form part of these systems and, when they all function correctly and efficiently, we have a healthy body.
Although it is not necessary to have an in-depth understanding of all the workings of the human body, it is useful to have a basic understanding of how all areas affect the parts relevant to a nail technician. It can help to explain such things as how a poor diet can affect nail growth, why a systemic disorder (a disorder of the body as a whole but arising from one of the systems) can be noticed in the nail condition.
A natural nail is an adaptation of skin cells and is surrounded by skin. Like hair and sweat glands they are considered to be appendages of the skin. Understanding how the skin is formed and why, helps us to understand how a nail is created and what may be happening if the nail is growing less than perfectly. The hands and feet are a collection of bones connected by muscles, nourished by a blood supply and surrounded by skin. A thorough knowledge of this part of the body is a good basis for a nail technician because it will; 
  • Help you to recognise any disorders and understand what may have caused them.
  • Assist your understanding of how these specific parts of the body function.
  • Demonstrate a knowledge and understanding of the area being worked on during treatments by answering any questions the client may ask; this will promote professionalism and generate confidence.
  • Help you choose the most suitable products for the client and understand their effects on the skin and nails.
The Cardiovascular System
(heart, lungs and circulation)
The Nervous System
The Digestive System
The Integumentary System
Human Body
The Reproductive System
The Urinary System
The Endocrine System
The Skeletal System
The skin is the largest organ of the human body and plays many essential roles. It weighs 3-4kg and measures approximately 2 square metres in an adult. It is a protective, helps with temperature control and is involved in one of the senses - touch. It is a giant, washable, stretchable, tough, waterproof sensory apparatus covering your whole body.
A body's skin has basically the same structure all over, but with some local variations, e.g. thickness, blood and nerve supply, colour etc. Hair and nails are modified skin cells.

The Skin

Classes of skin
There are two main classes of skin - hairless and hairy skin: both of which can be found on the hands and feet. (The other types are the mucous membrane that lines the inside of the body's orifices and mucocutaneous skin, which is found at the junction of the mucous membrane, e.g. lips and nostrils) We are mainly concerned here with the two major types.
Thick, hairless skin. Hairless skin is found on the palms of the hands and the soles of the feet. As the name suggests, this type does not have any hair follicles and therefore has no oil-producing glands, which makes it prone to dryness. It has many sweat glands, which assist in gripping objects and heighten sensitivity. Certain layers of the skin in this type are thicker and ridged to allow for wear and tear and to give a 'non-slip' surface. It has an epidermis of about 1.5mm in thickness and a dermis of about mm.
Thin, hairy skin. Hairy skin covers much of the body and, along with many structures found in all skin, has hair follicles. Its epidermal layer is about 0.07mm in thickness (half the thickness of hairless skin) and a dermis of about 1-2mm.
Layers of skin
It can be seen from the earlier diagram that there are three main layers of the skin; the epidermis, the dermis and the subcutaneous layer. In carrying out hand, feet and nail treatments, we are more concerned with the structure of the epidermis although the dermis does play some part.
The epidermis. The epidermis is of special interest as nails are evolutionary adaptations of this cell-producing area, as are hair, hooves, horns, scales and feathers. It is this layer that is treated in Manicures and Pedicures and an improvement to the condition of this layer is what is most sought by clients who request a Manicure.
The epidermis consists of layers of skin cells in various stages of development, growth, adaptation and death. The adaptation will depend on where in the body the skin is situated:
  • In a hair follicle the cells will form a hair.
  • In the matrix of the nail, they will form a nail plate.
  • In areas exposed to UV light, they will produce more melanin.
  • On the palms of the hands and soles of the feet, the clear layer (stratum lucidum) will be much thicker.
This progression of cells takes place from the lower level of the epidermis up through to the surface of the skin. The cells go through many changes during this journey. The progression of a skin cell in an area of skin that does not require any adaptations and is normal and healthy takes around four to six weeks. Skin disorders or other general health problems can influence this process. The skin cell ends up keratinised, flat and non-living and part of the protective stratum corneum. It is eventually shed from the skin and often found in house dust (or the inside of a pair of tights!).
The skin performs six main functions for the body.
1. Sensation. There are several different nerve endings found in the skin that respond to heat, cold, touch, pressure and pain. These are the sensory nerve fibres that end in the skin and detect the various sensations, sending messages to the brain. Motor nerve fibres are connected to the arrector pili muscles of the hair follicles. These cause the muscles to contract and lift the hair when the person is cold or frightened, causing 'goose bumps'.
2. Heat Regulation. The skin helps to keep the body at a constant temperature of 36.8-37 degrees. It is able to do this in several ways. One way is by dilation or constriction (vasodilation or vasoconstriction) of the blood vessels (capillaries) near the surface of the skin, thus retaining heat (in the case of vasoconstriction) or allowing it to escape (vasodilation). Another way is through sweat, produced by the sweat glands, which evaporates and cools the body. In addition, by having fat in the subcutaneous layer this can insulate the body. Sensory nerve fibres control the heat regulation process (as well as the skin's reaction to the 'fright, fight or flight' mechanism that results in sweaty palms).
3. Absorption. Some substances can be absorbed through the skin and will stay in that area or, more usually, enter the bloodstream and be carried throughout the body. (The effect of over-absorption can be seen after a good soak in the bath!) This absorbency can be useful when applying nourishing products to the skin but it can also be quite the reverse: the  skin can sometimes allow penetration of harmful substances. Absorption through the skin is one of the routes of entry of the human body for chemicals, together with inhalation and ingestion. The skin should be protected when using potentially harmful substances so that the chances of absorption are minimised.
4. Protection. Skin provides a waterproof coat that acts as a barrier to protect the body from dirt, minor injuries, bacterial infection and chemical attack. It does this is a number of ways.
  • The first barrier is a mixture of oil (sebum) and swear, which forms a slightly acidic film over the skin's surface. This discourages the growth of unwanted bacteria and fungus. (Plenty of bacteria live very happily on the skin but this is of the friendly or 'wanted' variety.) The sebum, the natural oil produced by sebaceous glands in the hair follicles of the skin, creates a waterproof coating that helps stop the skin losing essential water and, to a certain extent, also prevents the skin from absorbing too much water. The effect is minimal, as the skin can be quite absorbent, especially when it suffers from dryness, i.e. a lack of natural oil and moisture due to a skin condition or due to a lifestyle that destroys or removes too much oil ad moistures.
  • The second barrier is the uppermost layer of the skin (stratum corneum) that can act as a filter against invading bacteria. The healthy construction of this barrier provides good protection but it is very easily damaged. It relies on a good level of natural moisture to hold the keratinised skin cells together. On the hands, especially, this moisture is very often lost through environmental damage (detergents, water and so on).
  • The third barrier is the production of a pigment called melanin in the skin; this protects lower-level tissues against ultraviolet (UV) light damage. Darker skins have more melanin, which is a generic modification. Darker skins have evolved from hot countries where the skin needs a lot of UV protection. Paler skins evolved from cooler countries. Whatever the melanin content, the skin needs extra protection in the sun. Even on an overcast day there are plenty of UV rays around so a minimum of sun protection factor (SPF) 15 should be used. Hands are especially susceptible to UV damage and are often forgotten in  a sun protection regimen. 
  • In addition to these barriers, the skin has an early warning system against invasion by a chemical that the body will not tolerate or is sensitive or allergic to. Irritation on any part of the skin is usually a sign that an allergic reaction is starting. If the allergen (substance that is causing the reaction) is promptly removed, the reaction should subside. This reaction is more common when a substance is applied to the skin as part of a treatment, as it can be absorbed by the skin, but can also be the result of a substance getting inside the body either by ingestion (via the mouth) or inhalation (by breathing it in).
5. Excretion. Perspiration and some waste products, such as water and salt, are lost through the skin.
6. Secretion. Sebum, which moisturises and protects, is produced in the sebaceous glands.
Vitamin D formation. The skin is able to produce vitamin D through the action of UV light. This vitamin is essential to the absorption of calcium in the digestive system.
Storage. The skin stores fat and water that can be used by any part of the body as necessary.
Common conditions of the skin
  • One of the most common skin conditions as a nail technician is likely to come across is dermatitis. This literally means an inflammation of the skin and is non-specific (meaning the cause of the inflammation is not necessarily known). It is caused by an irritant to the skin or other part of the body activating the body's immune system so that white blood cells fight the invasion. Removing the cause can cute it.
  • Eczema, on the other hand, has symptoms very similar to dermatitis, in that it is an inflammation of the sin, but it is usually a generic condition.
  • Psoriasis is a condition where there is an over-production of skin cells and scaly patches of dry, dead skin can be seen.
Layers in the epidermis
1. The basal layer or stratum germinativum is where the skin cells are formed and is responsible for the growth of the epidermis. The cells contain the early stages of keratin, which is a protein, and will eventually form either a protective layer in the top of the skin or be adapted to form nails or hair. Some of the cells are melanocytes forming melanin. The cells here are continually dividing and reproducing themselves. This is a process called mitosis. The cells are plump, surrounded by the porous cell membrane, full of cellular fluid called cytoplasm and with an active nucleus that is responsible for cell reproduction and function and carries the genes inherited from our parents.
As these cells divide and reproduce themselves, they are pushed up and into the next layer of the epidermis.
2. The stratum spinosum, or prickle-cell layer, is where most of the cells have developed spines that connect them to surrounding cells. The nucleus is becoming less active as reproduction has slowed down or stopped.
Some of the cells, melanocytes that produce the pigment melanin, are extending through the spines to other ells. These are the cells that helps protect the lower layers of the skin from UV damage from the sun. Black skins that have evolved from very hot countries, for example, have significantly more melanin for maximum protection. Fair-skinned people who have been colder countries have much less pigment. Fair-skinned people who have been sunbathing or using a sunbed have produced extra melanin for their protection and this is what appears as a suntan. All skin colours will develop some degree of colour unprotected exposure to UV radiation. Sunburn is where too much radiation from the sun has been on the skin before more melanin has been formed to protect it. This radiation has been able to penetrate to lower levels and could cause problems in later life. There is a great deal of advice becoming available now as the effects of overexposure to the sun's radiation are further understood.
The amount of melanin can vary in the same area of skin. Patches of darker skin can be evident, sometimes on the back of the hands, face or chest. This can be due to an over-production of melanin and is stimulated by UV radiation, or caused by a hormone imbalance, for example during pregnancy or when taking a contraceptive pill. In older people, 'liver spots' on the back of the hand are caused by minor sun damage through their life. Freckles are triggered by exposure to sunlight and the numbers of them can be genetic. They can also be the result of sun damage and are often found on lighter skin as this type is more prone to suffer from exposure.
An opposite effect to the over-production of melanin results in lighter patches on the skin. This is called vitiligo or leucoderma, and it is where the skin has lost its ability to produce melanin. There is also a condition where the whole of the skin is unable to produce melanin, called albinism. People with this condition have very light skin and their hair and eyes lack colour.
None of these conditions is infectious, but the skin often needs extra protection and the hands are the areas that tend to suffer the most.
3. The stratum granulosum, or granular layer, is where the cells are beginning to die. They appear much less plump and the nucleus begins to break up. The cytoplasm (or cellular fluid) is thickening and becoming granular where keratin is beginning to form.
4. The stratum lucidum, or clear layer, is an adapted layer that is found only on the palms of the hand and soles of the feet - that is, the thick hairless class of skin. This extra layer gives specific characteristics to these areas. The hands and feet need to grip: the hands to hold things and the feet to grip to the ground. This clear layer helps to form the dips and ridges in our hands and feet that are known as our finger or hand prints (or feet also have the same prints). The skin in these areas does not produce sebum (natural oil) as it does not have any hair follicles: oil would make our hands and feet slippery. This area of skin only produces sweat from millions of sweat glands. A small amount of sweat, together with the ridges and dips, help our grip. Too much sweat makes our skin slippery and is usually a hormonal effect arising from an emotional moment such as fright or nervousness. Some people produce an excess amount of sweat on the palms of their hands. If such slippery hands are noticed, then the technician should take extra care in preparing the nail.
5. The stratum corneum, or cornified layer, is the uppermost layer of the skin. The cells have flattened, lost their nucleus and all the cytoplasm and have become keratinised. The flat cells are held together in a type of brick-wall arrangement by intercellular cement, which is mostly composed of lipids, a natural fat produced by the skin, together with sebum and sweat and keratin bonds. This forms a wonderful barrier and protection for the skin but it is easily damaged, especially on the hands. As newly keratinised cells are pushed up, the older flakes of the dead skin are shed in a process called desquamation in which the bonds are broken down. This will happen naturally but can be speeded up by environmental excesses such as pollution or hard water that break down he intercellular cement.
There are many conditions that affect this while cycle and there are skin disorders that can speed up the process, such as psoriasis, or others that can slow it down. It is very important for a nail technician to understand this process just described, for two reasons. First it shows us why the skin surrounding the nail and that on the hand must be cared for and, second, it is the basis of how nails are formed. Below the epidermis is another part of the skin that is very different and much thicker; this is called the dermis.
The epidermis
This layer carries the many structures that exist within the skin, such as nerves, blood capillaries, nerve endings, sweat ducts that open onto the surface of the skin as pores and sebaceous glands that open into hair follicles. It helps to serve the epidermis by carrying a vast network of capillaries and it gives the epidermis structural support.
Fibres in the dermis. One of the main features of the dermis is the network of strong fibres, of which there are two types; collagen and elastin. They are both made of a protein.
Collagen acts as a support to the skin, keeps it firm and gives it a plump, youthful appearance. Elastin gives the skin its elastic properties, allowing it to move and stretch but then return to its original position. In young skin, both types of fibres are plentiful, but as the skin ages, the fibres start to breakdown and are not replaced so readily. A lack of collagen allows the skin to form into wrinkles between muscles and a lack of elastin allows the skin to become softer and less firm.
The skin on the back of the hands does not always demonstrate a person's exact biological age as it is prone to misuse and damage and can look older than it is. The skin of the face is usually given more care and can often appear younger than the person's actual age. The skin on the backs of the hands has very little support in the way of muscles and stored fat. It does, however, have some very strong tendons that move the fingers and large blood vessels that supply the hand. As elastin and collagen become less effective, owing to age and damage from UV light and weather, the tendons and blood vessels become more apparent and thus add to the ageing appearance.
Other structures in the dermis
  • Nerves. The dermis carries a vast network of nerve endings that send a whole host of messages back to the brain where the messages are decoded and any work that the body needs to do is undertaken. Nerves give us our sense of touch and our fingertips are some of the most sensitive areas of our body because they have a large number of sensory nerves. In addition to the ability to feel, the nerves also provide a form of protection. If extreme heat is felt, sensory nerves, send an emergency message to the brain; the brain recognises the emergency and sends another message, via the nervous system and motor nerves, to the muscles that will then contract and move the relevant area of the bod away from danger. The type of nerve that sends a message to a muscle is a motor nerve. This whole procedure can take place in a fraction of a second.
  • Blood vessels. These make up a network of fine arteries, veins and capillaries that carry blood around the body to maintain the health of all the organs, including the skin. Blood carries nutrients (food) and oxygen to every cell in the body and removes waste products. The blood plays several essential roles in the working of the whole body. With regard to the skin, in addition to supporting cellular activity, its main role is connected with heat regulation. If the body is becoming too hot, the blood vessels in the skin dilate (become bigger). This assists heat loss. The reverse happens if the body is becoming cold: the vessels constrict, keeping, the blood deeper within the body to conserve heat.
        Increased blood supply in the skin causing redness without any obvious damage could be the body's 
        defence mechanism in action. A harmful item (such as a splinter) or chemical could have entered the skin
        and be causing an irritation. Cells within the dermis called mast cells release a chemical called histamine
        that increases the blood supply to the area and attempts to destroy the invader. This defence mechanism
        can progress from a slight redness, to itching and even to blisters and swelling. If the allergen (the
        substance that is causing the allergic reaction) or irritant is removed at the first hint of trouble, the
        reactions will often subside. If not, the condition can continue and result in a painful and distressing type of
  • Lymph vessels. Like the network of blood vessels, another system carries a fluid called lymph around the body. Lymph is similar in many ways to blood, in that it circulates to all the cells and carries a certain amount of nutrients, but its main role is as our body's defence mechanism. The lymph fights and removes bacteria and other invasive substances and carries excess fluid away from cells and surrounding tissue. The lymphatic fluid is 'filtered' by lymph glands situated all over the body. When the body is fighting an infection, glands often in the neck, can feel swollen and tender. 
       The lymphatic system does not have a pump to move it around in the way that blood has the heart. It relies,
       instead, on muscular movement to push it along. The flow of lymph can sometimes be sluggish and excess
       fluid and waste can build up in certain areas. There are no lymph glands sited near the feet and gravity will
       often cause excess fluid to collect in this area. The nearest glands are at the top of the leg in the groin and
       behind the knee. The nearest glands to the hands are on the inside of the elbows. Massage in these areas,
       with movements towards the glands, can help to increase circulation and reduce excess fluid in the hands
       and feet.
  • Sweat glands, with their own blood supply, are sited in the dermis and tube, or duct, leads directly from the  gland through the dermis and epidermis to open onto the surface and is seen as a pore in the skin. There are more swear glands on the palms of the hands and soles of the feet than anywhere else on the body. The most common type of gland, eccrine glands, are found all over the body and help regulate the body's heat by secreting small amounts of sweat all the time. This function also helps to regulate the body's salt levels and eliminates some waste products. Sweat helps to keep the skin hydrated and is part of the acid mantle that helps protect the skin. The level of sweat produced can be affected by the nervous system, for example emotions can raise the level, you may have noticed how anxiety often makes your palms very
        sweaty. Another, less common type, are apocrine glands, which are situated under the arm and groin. The            sweat secreted from these has been different chemical composition and hormones control its production.
  • Hair follicles. Another structure found in the dermis of the skin are hair follicles (with the exception of the palms of the hands, the soles of the feet and the lips). A follicle is a long sac-like shape where epidermal tissue extends from the surface of the skin down through the epidermis and dermis to its own blood supply. At the base of the follicle is an area called the germinal matrix where certain epidermal cells are instructed by their nucleus to adapt their growth and form together to create a hair. As in the epidermis, the new cells push the older ones upward and the hair grows up the follicle and out through the surface of the skin, with the cells completely keratinise and hardened, to become the hair shaft. Different types of hair grow on different areas of the skin. Although the same structure, the hairs have different characteristics, for example hair on the head has a longer life span than the hair of an eyelash. This is why eyelashes only grow to a certain length before falling out.
  • Sebaceous glands. Connected to the follicle is another structure: the sebaceous gland. This secretes a natural oil, sebum onto the hair shaft and the skin's surface. The oil helps to lubricate the hair shaft and plays an important role in the skin's protective functions. It helps create a waterproof barrier and therefore keep moisture in the cells of the skin and it also, together with sweat, creates a slightly acidic covering on the skin that acts as a bactericide and discourages the growth of unwanted microorganisms. This covering is known as the acid mantle.
  • Another structure attached to the hair follicle is a tiny muscle, the arrector pili muscle. When this contracts it causes the hair to stand upright in the skin. It does this to help trap heat (only effective in mammals with hair or fur covering their bodies) and also as a response to some emotional reactions. The effect is usually known as goose bumps.
Below the level of the dermis is a layer of stored fat. This fat is a supply of energy for the body and also helps contain heat within the body.
pH values. For the skin to remain healthy it needs to maintain the degree of acidity created by the sebum and sweat. If this changed too much the skin can become dry and if it changed drastically the skin is damaged. A scale called the pH scale measures acidity and alkalinity. Low pH number (1-6) are acidic, pH 7 is neutral and pH numbers (8-14) are alkaline. Examples of acids can be found in citrus fruits, such as lemons. This level of acidity would not damage the skin unless it were left on it for a period of time. Fruit acids are usually the base of a popular ingredient in skincare: alpha hydroxy acids (AHA). These can be useful in skincare as they help to remove dead skin cells and debris from the surface of the skin and generate cell renewal in areas that need assistance, such as the face and backs of the hands. Acids with low pH values would burn the skin, causing extreme irritations and blisters. 
At the other end of the scale are the alkalines that can have a similar effect on the skin. The milder alkalines are often used in skin treatments. Sodium hydroxide is sometimes used to soften and remove unwanted skin cells, for example in a cuticle remover. Soap is alkaline and is very drying to the skin. Extreme alkalines, such as household bleach, will damage skin in the same way that acids will.
The pH value of the skin is naturally 5.5-5.6 - that is, slightly acidic, and skin preparations that are labelled 'pH balanced' will have a similar pH value.

Blood Circulation

Blood needs to be carried to every cell of the body. It is the internal transport system that keeps the body functioning. It links every part of the body with every other part.
  • The blood carries food in the form of nutrients extracted from the digestive system and oxygen (in red blood cells) from the lungs to every cells, where they are converted into the fuel necessary to the functioning of the cell.
  • Waste products produced by every cell are carried away: carbon dioxide to the lungs, and the other waste products to the liver and kidneys where they are extracted from the blood.
  • Many different glands around the body secrete hormones. These are controlled by the brain and are the chemicals messengers that instruct the organs and tissues how and when to function. Hormones are transported by the blood system.
  • The body's defence mechanism to fight the invasion of foreign bodies, such as bacteria, viruses, harmful chemicals, etc. is also a major function of the blood . White blood cells are able to recognise any invasion and decide whether it needs fighting or whether it is harmless. If it needs to be fought, other cells in the blood attack and, if necessary, bring other systems of the body into the fight to help defend against disease or damage.
  • Blood circulation also helps with the control of heat. It distributed heat evenly around the body and, when necessary, helps it to cool down by dilating (opening) vessels near the skin's surface to lose some heat, or contracting those vessels to keep the heat nearer the centre of the body.
  • If the skin is damaged by a superficial cut, the tiny capillaries are served and the skin bleeds. Some of the cells (platelets) that form blood are capable of forming together and creating a clot that blocks the ruptured vessels and prevents further blood loss. The redness seen around a cut or other damage is an increase in the blood supply as it helps the cells to repair themselves.
The heart
The circulation of the blood needs a pump: the heart, a four-chambered, muscular organ. The muscles of the heart are a special type; instead of being individual fibres bundled together, they are connected so that the contraction in one are stimulates a wave of contractions throughout. Its muscle function is controlled by the autonomic nervous system, that is, it happens without any conscious effort on our part.
The upper right chamber (right atrium) of the heart receives deoxygenated blood that has travelled all around the body providing oxygen to the cells via two major veins: the superior and inferior vena cava. This travels into he lower right chamber (right ventricle) where strong muscles pump it directly to the lungs, close by, via the pulmonary arteries. The blood, low in oxygen but high in carbon dioxide that has been collected from the cells, collects oxygen from the tiny air sacs in the lungs that are filled when we breathe in and releases the carbon dioxide into the air sacs that is then dispersed when we breathe out.
When the blood has passed through the lungs, it is delivered back to the upper left chamber of the heart (left atrium) via the pulmonary veins. This blood, high in oxygen and low in carbon dioxide, passes into the lower left chamber (left ventricle) where very powerful muscles send it on its journey around the body again via a huge blood vessel, the aorta.
The heart beats on average 70-80 times a minute in a healthy body. This pumps starts when we are an embryo in the womb and continues until we die. Quite literally, our lives depend on it!
The blood travels along three main types of vessels: arteries, veins and capillaries.
1. Arteries are the vessels that carry the blood away from the heart (remember: A= artery and away). The blood is oxygenated and bright red. The artery has a thick muscular wall that helps maintain the pressure of blood in order for it to travel to all areas of the body. If an artery is cut, this pressure causes the blood to pump out with each heartbeat. Arteries are usually situated deeper within the body to protect them from this kind of damage.
2.Veins carry blood that is returning from all parts of the body to the heart. These vessel do not have the muscular wall of arteries but they do have non-return valves to keep the blood flowing in one direction, that is to the heart. The movement of the blood is mainly affected by the movement of the muscles in the areas around the veins and by the flow generated by the heart. This is one important reason why exercise and movement are essential for the healthy body. There are more veins than arteries and many are situated closer to the surface of the skin. If a vein is cut, the blood is seen to well out rather than the way it pumps out of an artery.
3. Capillaries are the link between the arteries and veins and allow the blood to reach every cell in the body. They are tiny, thread-like vessels with very thin walls and they branch out to every extremity. Their walls are so thin that the nutrients and oxygen carried in the blood are able to pass through the wall and into the tissue fluid that bathes the spaces between cells. Red blood cells are too large to pass through the capillary walls, just the clear blood plasma carrying the nutrients is transferred. These substances, which are essential for life, flow naturally through the wall from an area of high concentration (the blood) into an area with a lower concentration (the tissues). Waste materials from the cells, in the same way, flow from the tissues into the blood to be carried away for elimination.
For the purposes of Manicure and Pedicure, an understanding of how the blood circulation works is requires. However, you will only need to remember the main arteries and veins in the hand, arm, leg and foot.
Hand and arm
The artery that serves the arms branches indirectly from the aorta and is know as the brachial artery. It runs down the middle of the inside of the upper arm, quite deep, to just below the elbow where it branches into:
  • The radical artery running down the thumb side of the lower arm where it supplies oxygenated blood to that side of the hand and the back of the hand. it is commonly used as a pulse point as it is quite close to the surface in the wrist and the beat of the heart can be felt.
  • The ulnar artery that runs down the other side of the lower arm, crosses the wrist and supplies that side of the hand and the palm.
There are interconnections between the radial and ulnar arteries that from the palmar arches: known as the deep and superficial arches. Branches from these serve the main areas of the hand (metacarpal arteries) and more branches run down the fingers (digital arteries) to end under each nail to supply the nail unit with blood.
The hand and arm are served by more veins than arteries to carry away the deoxygenated blood from the area. The deeper veins have the same names as the relevant arteries, that is the radial vein serving the thumb side of the hand and lower arm and the ulnar vein serving the outside of the hand and lower arm, plus the digital, metacarpal and palmar veins.
In addition to the major vessels, there are veins closer to the skin, known as superficial veins. Many of these can be seen through the skin on the back of the hand (dorsal venous network) and the palm (palmar venous plexus) and lead into the main superficial veins:
  • Basilic vein, seen on the back of the hand on the little finger side and up the centre of the forearm.
  • Cephalic vein seen on the back of the hand around the thumb and up the forearm to the elbow.
  • Median vein from the palm of the hand up the forearm where it joins the basilic vein.
Foot and lower leg
A large and important artery branches into each leg around the groin area: the femoral artery. It goes behind the knee where it becomes the popliteal artery and branches into the main lower leg arteries:
  • The anterior tibial artery passes between the bones of the lower leg towards the front of the leg to the ankle and from there to the top of the foot at the dorsal pedis artery. This branches to form the dorsal arterial arch and dorsal digital arteries. It then passes through the foot to from part of the plantar arch on the sole of the foot.
  • The posterior tibial artery passes down the centre of the back of the leg, past the ankle to the inside of the sole. Here it branches to form the lateral and medial plantar arteries, which in turn supply the arteries to the toes. It also branches near the knee to form the peroneal artery running down the outside of the leg towards the heel.
Like the hand and arm, there are deep and superficial veins serving this area. The deep veins follow and have the same names as the main arteries. The two main superficial veins are the long saphenous vein, which begins at the dorsal venous arch on the top of the foot and runs up the inside of the lower leg and thigh to join the femoral vein, and the short saphenous vein from the ankle up the back of the calf to the popliteal vein at the knee. Obviously, there are many branches and smaller veins in the area that remove the deoxygenated blood and take it on its journey back to the heart and from there to the lungs.
Some common conditions involving the blood system
  • Heart disease, even if it is minor, can cause a problem with circulation, leading to poor circulation at the extremities of the body. Weak nails and dry skin can result and nails can appear bluish in colour due to poor delivery of red, oxygenated blood.
  • A lack of essential vitamins and minerals in the blood can affect the condition of skin and nails.
  • Anaemia: this is a condition that results in a shortage of red blood cells, that is the cells that carry oxygen. This shortage affects the whole body. The most common symptoms are extreme tiredness and pale skin (and nail beds). In some instances, the body just needs extra iron. This condition is especially common in young girls who don't have a proper diet and woman whose periods are heavy (for example during early stages of the menopause).
  • Varicose veins: this is an impaired functioning of the valves in the veins. The veins can become swollen and tender and can result in ulcers in extreme cases. They should be avoided during a leg massage.
As with all conditions, a nail technician must never diagnose for their client. Understanding how the systems of the body work helps technicians to decide the best type of treatment for their client together with informed aftercare advice.

The Lymphatic System

The lymphatic system is a second system of circulation, closely associated with the blood circulation. It is just as complex and just as essential to the survival of the human body.
The system carries a fluid known as lymph. Lymph is a clear fluid that bathes every cell in the body and is the carrier of all the cellular requirements and waste products. Lymph carries white blood cells that are transported in and out of the bloodstream as necessary. It is the main ingredient of the human body's immune system. Like veins in the blood system, the vessels carrying the lymph do not have muscular walls and the pressure of a heart to act as a pump. The movement of the lymph relies on movement in nearby muscles and close arteries.
The main functions of the lymphatic system are to:
  • Drain the intercellular fluid; approximately 15 per cent of this fluid is not reabsorbed by the capillaries.
  • Be responsible for the transportation and absorption of dietary fats.
  • Initiate and regulate the immune responses.
The network of lymphatic vessels contains approximately 100 lymph nodes around the body and lymph passes through at least one of these before eventually draining into venous blood. The nodes are small, kidney-shaped structures and have two main functions:
1. They are filters of the fluid and will remove any unwanted microorganisms and other foreign materials. The unwanted organisms are stored here and specialist cells (called macrophages) engulf and destroy the invaders.
2. They store several types of white blood cells needed for the fight and destruction of infections and release them as required.
When a harmful microorganisms enters the body, the lymph nodes usually become swollen with large amounts of the white blood cells (lymphocytes) that are ready to be released to destroy the invader.
If lymph nodes or vessels become blocked or the movement of lymph becomes sluggish for any reason (for example, lack of exercise, low metabolism, etc.) then local swelling may be noticed: known as oedema. Excess fluid is not being efficiently removed from the tissues and is very often experienced around the ankles. Massage techniques provided during a Manicure and Pedicure can encourage an efficient circulation of lymph and help remove excess waste productions from the area.
All of the organs and systems of the human body are connected with and are influenced by each other. Some of the organs that are specifically associated with the lymphatic systems are:
  • The spleen, which is located in the abdomen. It filters the blood by breaking down old red blood cells and also manufactures the lymphocytes essential to the immune system.
  • The tonsils, which are patches of lymphatic tissue at the back of the throat. Their function is to help trap harmful materials trying to enter the body via breathing, eating and drinking.
  • Peyer's patches - similar in function and structure to the tonsils - are located in the small intestine to destroy the bacteria that could thrive in that environment. 
Some common conditions concerning the lymphatic system
  • The condition that a technician is most likely to come across is dermatitis, where the immune system rushes to protect the body at one of its routes of entry, that is absorption through the skin.
  • Blisters are usually filled with a clear fluid; this is lymph where it collects to protect the skin.
  • Oedema is a condition where fluid collects in certain areas. This is often seen in the feet and ankles as they are so far away from the heart. Exercise and stimulation by lymph drainage massage will help.
  • Lymphoedema is similar to oedema but is due to an obstruction of the lymph vessels draining the area.
The skeleton of the human body is a living structure and the framework that supports and protects the whole body. It functions in the following ways.
  • Support: the skeleton creates the shape of the body allowing it to function, that is stand erect and move via the attachment of muscles. There are also other types of connections that provide support for the organs of the body.
  • Protection: sections of the skeleton create cavities that encase and protect some essential structures of the body. The skull provides an exceptionally strong cavity for the brain; the spine provides a canal for the spinal cord that connects the brain to all other parts of the body; the ribcage provides a cavity and protective structure for some of the most important and delicate organs, e.g. the heart, lungs, spleen. 
  • Manufacturers red blood cells. The central part of many bones is filled with a substance called bone marrow and is where red blood cells are manufactured. 
  • The skeleton also stores minerals.
The bones of a very young person are relatively soft and slightly bendy. Babies are born with 270 soft bones (64 more than an adult). Many of these will fuse together by their early twenties into the 206 hard, permanent bones.
All the bones articulate (move) against each other in order that the body can move. The areas where two or more bones come together are called joints. There are three types of joint:
1. Immoveable joints or fibrous joints. These are the skull and the pelvis. Each of these skeletal structures is created from several separate bones that are joined together with strong fibrous tissue. There are certain times when these need to have some movement. The skull needs to change shape during birth and a woman's pelvis can sometime slightly enlarge during pregnancy and birth.
2. Slightly moveable joints or cartilaginous joints. The joints are found between the many bones in the spine where some movement is needed but is restricted.
3. Moveable joints or synovial joints. There are many more of these and they also fall into different categories depending on their range of movement:
- Ball and socket joints allow circular movement, for example the shoulder and hip joints.
- Hinge joints allow a movement of approximately 90 degrees; these are found in the elbows, knees and fingers.
- Gliding joint allow surfaces to glide over each other, for example the wrist and ankle joints.
- Pivot joints allow rotation around an axis, for example the movement allowed by the bones in the lower arm (radius and ulna) that gives the hand its circular movement when the palm is turned up and down.
For the purposes of the hand and foot treatments, it is only the moveable (synovial) joints that are relevant.
The ends of the bones need protection from articulating against each other and a system in each joint allows this movement and offers protections. The joint is surrounded by the synovial membrane that secretes synovial fluid and lubricates the joint to allow free movement. The bones are protected by cartilage, gel-like substance, that also provides some cushioning. 
There are several disorders and diseases that affect joints and therefore have implications during a hand or foot treatment. One of the most common is arthritis that can be caused by an illness or by wear and tear. Arthritis can cause the joints to become inflamed, painful and, in later stages, deformed.
For the purposes of massage, it is necessary to understand the positioning of the bones in the hands, lower arms, feet and lower legs and how they move against each other.

The bones of the hands and feet

The forearm
The elbow joint is where the large upper arm bone, the humerus, articulates mainly with one of the two forearm bones, the ulna, creating a hinge joint. The other forearm bone is the radius, attached to the ulna at the elbow.
The presence and positioning of two bones in the forearm allows the hand to rotate, that is, the palm can be turned uppermost or it can rotate at the wrist so the back of the hand is uppermost. This is achieved by the articulation of the bone on the thumb side of the arm, the radius, which rotates over the bone on the little finger side of the arm, the ulna. This is a pivot joint,
The end of the radius articulates with the bones in the wrist, which, together, provide a wide range of movement for the hand.
The hand
A the wrist there are several small bones, carpals, that glide over each other (gliding joint) allowing a great range of movement for the hand. There are eight carpals arranged in two rows of four. These bones fit closely together and are held in place by ligament's.
The palm of the hand has five bones, the metacarpals, which can be felt along the back of the hand and these articulate with the finger bones, the phalanges.
The hand has four fingers, each with three phalanges, and a thumb with two phalanges. Each bone of the fingers and thumb articulates with its neighbour in a hinge joint, which allows for the vast amount of dexterity a human hand can demonstrate. There is a certain amount of rotation at the joint between the metacarpals and the phalanges that allow further movement for the fingers and thumb. The hand has in total 27 bones.
Our nearest relations in the animal kingdom, the apes, are very close to us in terms of anatomy and physiology. One of the main differences, which some evolutionists believe is the main reason humans evolved much further than the apes, is the movement we have in our thumb. A human thumb has a wide range of movement allowing us to become much more dextrous. An ape, as indeed a young baby learning to control their hands, can only move their thumb towards the hand and away in a pincer movement. The full movement of the human thumb allows for minute control and dexterity.
The lower leg
The arrangement of bones in the lower leg is, on many ways, similar to the lower arm. The longest bone in the human body, the femur, or thigh bone, extends from the hip to the knee. The femur articulates with one of the lower leg bones, the tibia, at a hinge joint, the knee. The knee has an extra bone that acts as protection, the patella.
The lower leg, like the lower arm, has two bones that allow a certain amount of rotation of the foot. The larger one, the tibia, runs down the centre and the inside of the leg and is the one you can feel with a sharp edge as the shinbone. This articulates with the talus (one of the ankle bones) at the ankle. The smaller bone, the fibula, articulates with tibia at the knee then runs down the outside of the leg to articulate, like the tibia, with the talus. It is the knobbly ends of these bones that stick out on either side of the ankle.
In the ankle, there are a collection of seven bones, the tarsals, that glide over each other. The largest of them, the calcaneus, forms the heel of the foot. On top of this is the second largest, the talus, which articulates with both the tibia and fibula. There are then two rows of two and three bones, respectively.
The five bones that can be felt on the upper foot are the metatarsals. These articulate with the phalanges and, like those in the hand, there are three bones for the smaller toes and two for the big toe. Unlike the fingers, the movement in the toes is more restricted. Their main functions are concerned with grip and balance.
The foot
The foot is obviously essential to the balance and walking movement of the human body. Consider its a shape as being similar to a tripod, with the points of contact being the heel, under the big toe and under the little toe. This structure is able to support the weight of the body when standing, walking, running, etc. and gives it balance when the body weight shifts to the various contact points. The arches in the middle of the foot, while being part of this structure, also allow for the free flow of the blood to all parts of the foot without any pressure from contact with the surface.
Some common conditions concerning the bones
  • Arthritis is a very common condition affecting the joints.
  • Broken bones are relatively common and a technician is likely to come across this condition.
  • Bunions are a painful condition affecting the base of the big toe. The big toe leans towards the second toe and there is a deformity of the joint, sometimes with a painful, fluid-filled swelling. There are several causes, even heredity, and poorly fitting shoes is just one of them. If severe the only solution is surgery.
  • Rheumatoid arthritis is an inflammation of the connective tissue in the joints similar to arthritis but often more aggressive.

The muscles of the hands and feet

We have looked at the structure of the skin, the blood and lymph circulation systems and the skeleton. Every system in the body relies on every other system to function. Think about how muscles affect the anatomical areas we have looked at so far.
The skin has muscles lying directly beneath it. These muscles in the face provide us with the wide range of facial expressions that are so important to human communication. The loss of muscle tone or substance creates visible signs of ageing and illness. This is especially visible on the face, the backs of the hands and the neck.
Muscles play a very important part in the circulation of blood and lymph. The heart mainly comprises a specialised muscle tissue that keeps it beating and pumping the blood around our body. It is muscle movements in associated areas that encourage the flow of lymph around the body. The skeleton can support and protect but it needs the vast array of muscles to allow it to move.
It would be impossible for a human body to do anything without muscles. Everything you conceive in your brain is expressed in muscular motion: talking , walking, drawing, reading, laughing, etc. Muscles turn energy from nutrition into movement. They are long-lasting, self-healing, and are able to grow stronger with practice.
There are three different types of muscle in the human body:
1. Skeletal muscle. This is the type we can see and feel. We are usually aware that they are moving and that we are controlling them. They are attached to the skeleton and work in pairs, that is one muscle moves the joint one way and the other moves it back. Muscles can pull but cannot push. The only times we do not control them voluntarily is when our nervous system sends an emergency message of self-protection, such as touching something hot or blinking if something approaches our eye. Skeletal muscles are the body's most abundant tissue and comprise approximately 23 per cent of a woman's body weight and 40 per cent of a man's.
2. Smooth muscle. This is the muscle associated with our organs and blood vessels. It is found in the digestive system (e.g. stomach and intestines for churning food and moving it along), blood vessels (for pumping blood along the arteries), bladder, airways and uterus. The body is largely unaware of its control over this type of muscle; it is triggered automatically by signals from the brain.
3. Cardiac muscle. This is only found in the heart and is a specialised muscle where the fibres are connected together and are controlled by the brain.
For the purposes of treatments, only skeletal muscle is relevant, although an understanding of the basic system of the body is important.
The basic action of a muscle is contracting. An example of this can be seen in lifting your lower arm. The muscle on the front of your upper arm, the bicep, contracts and lifts the lower are, and can hold it there. When this action is no longer needed, the bicep relaxes, but the arm needs to be returned to its original position. This is when the tricep, on the back of your upper arm, contracts to bring the lower arm back. This example shows how skeletal muscles work in pairs because their basic action is to contract.
The order to a muscle to contract comes from the brain via the nervous system. The motor nerves situated in all muscle fibres initiate what is actually a chemical reaction that causes the minute fibres to contract and shorten. The chemical reaction needs specific nutrients and oxygen, which are carried to them via the blood system. There are two types of contraction: isotonic and isometric contraction.
Isotonic contraction is where the length of the muscle shortens, as in the lifting of the forearm. Isometric contraction is where the muscle is put under tension but is not necessarily shortened. An example of this would be carrying a heavy bag. The force generated by the muscle allows the arm to do this. The toning of a muscle needs to be repetitive movements with little associated weight, while the building of muscle needs the tension and force required to move or support heavy weights.
Skeletal muscle is made up of bundles of fibres. It is also called striated muscle as stripes can be seen when viewed under a microscope. The fibres can be thought of as long cylinders called myofibrils (muscle protein) that surround filaments. It is the filaments that actually contract the myofibrils and therefore the fibres that are connected in parallel bundles.
Tired, overworked or slightly, damaged muscles have myofibrils that are not fully relaxed and feel like knots in the muscle. Stress often causes a contraction that does not relax. A good massage, using techniques that stroke the fibres and encourage them to relax and return to their resting position, is very helpful and pleasant for the client. This is relatively easy to achieve on the lower arms, hands, lower legs and feet, as the muscles are not large and are close to the surface of the skin. On other parts of the body, such as the back and upper leg, the muscles are large and a much firmer pressure is needed to reach the deep muscles.
Associated with the muscles are two other types of tissue:
1. Ligament. This is a short band of fibrous tissue that binds bones together.
2. Tendon. This fibrous tissue attaches the muscle to the bone. An example of tis is found in the Achilles heel, the tough ridge at the back of the heel that joins the heel to the calf muscle.
Both of the above can be damaged, usually by overstretching. For massage purposes, it is necessary to know and have a basic understanding of how muscles work and their positions in the arm, hand, leg and foot.
The lower arm and hand 
The muscles in the lower arm are concerned with the movements of the hand (the upper arm has the muscles that raise and lower this part of the arm). The muscles work in pairs, as explained above.
  • One of the muscles that extends (or straightens) the wrist ad helps to turn the hand is the extensor carpi ulnaris. Its name should suggest to you where it is and what it does. It starts at the humerus, runs down the ulna side of the arm to the little finger side of the carpals.
  • The opposing muscle to this, which bends the wrist and turns the hand in the other direction, is the flexor carpi ulnaris.
  • There is another muscle that extends the wrist and helps turn the hand that runs down the radius side of the arm: the flexor carpi radialis.
  • Its opposing muscle is the flexor carpi radialis.
  • The muscle that rotates the hand to bring the palm downwards starts at the humerus and extends down the top of the ulna to the base of the radius and is known as the pronator teres.
  • Its opposing muscle, the supinator teres, follows a similar route and connects with the other side of the radius.
Tendons from these muscles run down the hand to each finger:
  • Extensor digitorum tendons run down the back of the hand, right along the fingers and allow the fingers to extend. These can be seen and felt as the fingers move and are particularly obvious in older hands as the skin loses its support.
  • Flexor digitorum tendons are the opposing tendons that are in the palm of the hand and fingers and allow fingers to bend.
The hand also has a group of muscles in the palm that gives the thumb and little finger their range of movement. The wrist has four important ligaments that hold the carpals together, while allowing them to slide over each other during the movements of the wrists.
The lower leg and foot
The muscle groups in the leg and foot have similarities to those in the arm and hand. However, in addition to the range of movements, these muscles are important for walking and balance.
  • The large calf muscle, which starts at the femur behind the knee, runs down the lower leg to where it joins the heel (calcaneus) via the Achilles tendon and is known as the gastrocnemius. This muscle flexes the ankle to straighten the foot.
  • Its opposing muscle, the anterior tibailis, flexes the foot to bring it up towards the leg. It attaches at the upper tibia, runs down the front of the leg to join the metatarsals.
  • The muscle that helps to stabilise the body when standing and flexes the foot inwards is the soleus. This starts with the upper tibia and fibula and joins the tendon of the gastrocnemius.
The muscles of the foot that lift the toes are the extensor digitorum brevis and they continue onto tendons for each toe: the extensor digitorum tendons. Under the foot is the flexor digitorum brevis leading to the flexor digitorum tendons.
Some common conditions concerning muscles
  • Sprains and strains are a frequent problem with muscles. They mainly involve the ligaments, which can be overstretched and sometimes torn.
  • A torn muscle, especially in the leg, is quite common, as are strained muscles that have been overworked.

The Nervous System

The organs and tissues that make up the nervous system are the brain, spinal cord, sense organs (eye, ear, skin, nose, tongue) and the nerves. The systems can be differentiated into two main structural areas:
1. The central nervous system (CNS) comprising the brain and spinal cord.
2. The peripheral nervous system (PNS) with all the sensory and moto neurones.
The functions of the nervous system can also be differentiated into two categories.
1. The voluntary nervous system. These movements are under our conscious control, for example walking, speaking, etc.
2. The autonomic nervous system. These movements are out of our conscious control, for example blinking, breathing and movements in the digestive organs. This system regulates the muscles in the skin (around the hair follicles and the smooth muscle of our internal structures), blood vessels, the iris of the eye and the cardiac muscle of the heart.
Messages to and from the brain and spinal cord use the peripheral nervous system and are transmitted along nerve fibres. Along these fibres are neurones. These are cells like tiny batteries that power the electrical circuits in the body (the method by which messages are transmitted). They transmit from cell to cell for communication, control and interpretation of the sensory input.
The main types of nerves are:
1. Sensory nerve fibres carry impulses from the nerve endings in the sensory organs (for example the skin) back to the brain via the spinal cord. This keeps the brain informed about our external environment.
2. Motor nerves fibres relay messages from the brain and spinal cord to instruct relevant parts of the body to respond, for example bending an arm or jerking away from unexpected heat.
3. Mixed nerves that function as both a sensory and motor nerve.
4 The autonomic nerves are working al the time to control the subconscious workings of the body. This includes temperature control that affects the skin.
The skin is the largest sensory organ and responds to touch, pressure and heat. Receptors in the epidermis and dermis can detect pressure, vibration, mechanical stimulation, thermal and noxious (harmful) stimulation. The hands have a plentiful supply of nerves, especially on the fingertips. Although all skin is involved in the sense of touch, the fingers are especially sensitive. There are some fairly common disorders, either permanent or temporary, that can affect the nervous system in the hands and feet. They can cause phenomena such as a loss of sensation in the skin and an inability to feel or quickly respond to extreme temperatures. This is why care must be taken when using heated products or equipment. Their temperature must be tested before the client uses them.
Some disorders involving the nervous system
  • Parkinson's disease affects more than 1 person in 1000 and 1 in 100 of those over 60. It results in shaking, tremors and muscular rigidity. It is a progressive disease.
  • Multiple sclerosis affects the nerve fibres resulting in a progressive impairment of muscular control.