The Nerves. a nerve is a collection of fibres that send messages from the organs of the body to the central nervous system. The skin is the largest organ of the body and as one of the major organs therefore contains many nerve fibres. There are two types of nerves within the skins structure.
1. Motor nerves 2. Sensory nerves
Four sensations are experienced through the skin.
1. Pressure 2. Touch 3. Pain 4. Temperature
The sensory nerves and receptors lie deep within the dermis but those that sense pain are to be found in the lower epidermis. As sensations from outside the body, such as heat and cold are picked up by the nerves, a message is sent along the central nervous system and the brain decides how to act on this information. If the brian decides action is needed it sends a message along the motor nerves to the necessary organ or muscle. A example would be that if the brain sensed cold it would send a message to the arrector pili muscle to contract which would raise the hair on the skin and so trap air next to the body for warmth, what we know as goose bumps.
Hair Follicle. A hair follicle is a depression of epidermal cells pushed deep into the dermis responsible for the production of the keratinised structure called hair. Blood vessels in the dermal papillae supply the food and oxygen necessary for hair growth. The arrector pili muscle is attached to the follicle and pulls the hair upright when the muscle is contracted.
Sebaceous Glands. These glands are found all over the body with the exception of the palms of the hand and the soles of the feet.They usually open out into the hair follicle but some are found on the surface of the skin, they help to keep the skin soft and supple by preventing moisture loss from the dermis. An acid mantle is formed by sweat and sebum protecting the skin from harmful bacteria. As the sebaceous gland increases activity, seborrhea or oily skin occurs, which can lead to blocked pores and other skin conditions. The reverse will cause dry and flaky skin. e.g. dandruff.
Sweat Glands.Two types of sweat glands deep in the dermis consist of long narrow tubes or ducts that pass up through the epidermis to the surface, where sweat is excreted through an opening in the skin called a pore.
1. Eccrine. These glands only secrete water and salts and are found all over the body. Their only function is to regulate body temperature.
2. Apocrine. These glands are found in the armpits and genital areas and open into hair follicles instead of the surface of the skin. These secrete water, urea and fats. It is the breakdown of this type of sweat that causes body odour.
The dermis lies immediately beneath the epidermis and this layer contains blood vessels, lymph vessels, nerves, sweat and sebaceous glands, hair follicles, arrector pile muscles and papillae. The dermis is comprised of two separate layers.
1. The papillary layer 2. The recticular layer.
The papillary layer contains the small cone-like projections which extend upwards into the epidermis, called papillae. Papillae contain small blood vessels or nerve endings. This layer also contains some melanin.
The recticular layer is the lower area of of the dermis where the blood and lymph vessels, sweat and sebaceous glands, hair follicles and the arrector pili muscles are situated.. It also has a dense network of collagen fibres which run parallel to the surface. These fibres give the skin its elasticity and can be damaged by ultra violet light.
The Subcutaneous tissue
This layer is made up of fatty tissue known as adipose tissue. It is not technically skin, but anchors the skin and acts as a protective cushion to the body. It also stores fat to be burnt for energy. It can vary greatly in thickness according to age, sex and health of the body. Sitting beneath the dermis layer it contains:-
Blood Supply is through a network of arteries that run parallel to the surface of the skin contained in the subcutaneous layer. These branch into smaller capillary networks around hair follicles, sebaceous and sweat glands.The capillary network is responsible for transporting food and oxygen to the living cells. The amount of blood flow is controlled by the nerve endings in the capillary walls.
Lymph. The lymphatic capillaries drain away the tissue fluid which contain waste products from cell activity and foreign bodies such as bacteria. Throughout the dermis there is a network of fine lymph vessels.
* The structure of the skin
* The grow pattern of the natural nail
* Contra indications to nail treatments
* Contra actions arising because of treatments
The Epidermis, the top most layer is made up of 5 layers of tissue that contain no blood vessels and very few nerves.Going from the top layer down the 1st layer is:-
Stratum Corneum (horny Layer) this is the outermost layer and is composed of several layers of flattened irregularly shaped cells.They take this flattened shape due to evaporation of their fluid content.This layer consists almost entirely of Keratin.
Stratum Lucidum This layer has cells with no Nuclei, which are narrow, transparent and have little outline. The cells at this stage are nearly at the end of their life cycle and are becoming dyhydrated.The keratohyalin granules that are present are being turned into keratin.
Stratum granulosum (granular layer) As the cells from this layer gradually rise to the surface they flatten, become larger and accumulate granules containing keratohyalin which helps in the production of epidermal keratin.
Stratum spinosum. This layer is composed of several layers of cells varying in shape and size.The upper portion of this layer is known as the prickle cell layer. The cells are linked by way of fine threads which give them a spiky appearance.
Stratum germinativum (basal layer) These cells are tightly packed together and constantly being reproduced. As cells are pushed upward toward the surface they become components of other layers. This cellular regeneration can be increased or decreased by a number of factors including ill health or age. This layer also contains the pigment-bearing cells known as melanocytes which produce melanin, a necessary process when trying to get a suntan. The
The importance of dermatology( the study of the human skin) to the nail technician is so that we can educate our clients on the processes they can use to maintain healthy skin on their hands and feet.
The professional nail technician must know when not to perform treatments, recognise, but not diagnose conditions and be able to advise clients in the event of any contra indications occurring. The study of anatomy and physiology may be boring but it is an integral part of your job and will help to protect us and your clients from bad practices.
At fourteen weeks the foetus in the womb has developed the area where the nail plate will grow and the nail plate can be seen growing out of the proximal nail fold. Around 21 weeks the nail plate will be completely formed and tiny fragile free edges can be seen.
The cells of the nail are flattened and filled with Keratin. They have no nuclei and are thought to to be similar to the cornified or uppermost layer found in the epidermis. Nails begin their life in the Matrix which extends to include the deep layers of the underside of the Proximal nail fold. This area is where the cells divide and produce keratinocytes, capable of producing rapid keratinisation. Keratin is a tough fibrous protein polymer made up of amino acids and on average the fingernail plate is 100 cells thick. As the cells leave the Matrix most are already bonded. Inside each cell are long fibrous keratin tissues that bond into the next cell along each of its three to six sides. There is very little lipid or fat between the cells of the nail plate which is why the nails are more permeable to water than the skin.
Although nail technicians work on the nail itself, we need to be aware of the surrounding areas. The diagram to the left shows these areas.
The Nail Bed is under the nail plate and extends from the front edge of the matrix to the hyponychium which is just below the free edge. Two types of tissue make up the nail bed. 1. epidermis: is attached to the nail plate 2. dermis: is attached to the bone underneath. It contains many thousands of tiny blood vessels to carry food, oxygen and nutrients to the nail whilst also taking away toxins and waste.
The Hyponychium is found directly below the free edge of the nail and forms a watertight seal that prevents bacteria and viruses from attacking the nail bed. It also attaches to the two lateral nail folds, if the seals are broken or damaged there is a possibility of infection.
The Eponychium sometimes wrongly referred to as the cuticle acts as a seal to the matrix. Care should be taken when pushing back the cuticle not to damage the eponychium as infection can occur.
The Perionychium are curved folds bordering the sides of the nail plate, referred to as lateral folds. They extend marginally onto the nail plate and form a watertight seal.
The Nail Grooves guide the nail plate down the finger.
The Mantle or proximal nail fold is a deep fold of skin at the base of the nail where the root is embedded. This area should not allowed to become dehydrated as the skin may split and tear and infection can occur. Regular use of hand creams will keep the area in good condition.
The Matrix is a small area of living tissue directly below the Mantle. This is where the nail is made creating the cells to make the nail plate. The cells are white as they leave the matrix and this can be seen on the nail plate as a curved area called the Lunula. If the matrix is damaged the nail often will grow malformed. The length and width of the matrix will determine the shape and thickness of the nail plate.
The Lunula is the thinnest part of the nail plate, transparent as the cells have not yet fully keratinised. The lanula is half moon in shape.
The Cuticle just above the eponychium and acts as a watertight seal to prevent harmful bacteria from invading the soft tissue of the matrix. The true cuticle constantly sheds a thin layer of skin which attaches itself to the nail plate as it emerges from the matrix. This skin must be removed from the nail plate otherwise the acrylic will lift from the nail.