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Nails, Hair & Teeth

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Nails, Hair & Teeth Nails Components of the Nail system • Free Edge • Hyponychium • Perionychium • Eponychium • Nail Plate • Cuticle • Nail Bed • Nail Folds • Matrix • Mantle • Lunula • Nail Wall • Nail Grove Components of the Nail system Free Edge • The part extending beyond the end of the skin of the fingertip Hyponychium • Forms a seal between the free edge of the nail & the skin of the fingertip Perionychium • The skin that overlaps the sides of the nail. This is the site of paronychial infections, hangnails & ingrowing nails Eponychium • Forms a seal between the skin & the nail plate that protects the underlying matrix from infection. It sits beneath & is protected by the cuticle Nail Plate • The fingernail is the nail plate. It is a protective shield of translucent keratin for the nail bed beneath. Grooves on the underside of the nail plate attach it to the nailbed. Blood vessels in the nailbed give the pink colour Components of the Nail system Cuticle • A layer of skin growing from the base of the nail over the nail plate. It works with the Eponychium to create a seal which protects the Matrix from infection Nail Bed • As the Matrix produces new cells, which pushes the growing nail forward, the nail bed adds cells to the underside of the nail. This thickens & strengthens it as it grows out. The nail bed contains blood vessels, nerves & melanocytes Nail Groove • The grooves at the lateral sides of the nail plate along which the nail grows next to the lateral nail folds (paronychium) Nail Folds • The nail folds are the folds in the skin which protect the matrix. The edges of the nail plate sit into the folds. The root of the nail is protected by the Proximal nail fold and the Edges by the lateral Nail Folds Components of the Nail system Matrix • The Matrix produces the cells of the Nail Bed & Nail Plate. It lies mostly beneath the nail & nail bed. The tip of the root is visible in the Lunula. The Matrix produces Keratin cells & pushes the nail forward Mantle • A deep fold of skin found above the Matrix at the base of the nail before the Cuticle Lunula • The half moon of the nail. It is the visible front end of the Germinal Matrix which extends underneath the Nail Plate. Most visible on Thumb nails Nail Wall • The folds of skin which overlap the sides of the nail plate & provide protection Nail Growth • Rate of Growth varies – may be up to 3mm per week for Fingernails & 1mm for Toes • Whole Fingernail is replaced 2-3 times a year • Toenail is replaced every 12-18 months • Growth rate peaks in teens • May increase in pregnancy, summer or during sleep Factors affecting Nail Growth • Health – Shape, Integrity & Colour of nail can be affected by diseases of the Lung, Heart, Kidney, Liver & Thyroid • Age – The growth rate slows with age & protein structure becomes more brittle and weak • Diet – Vitamin & Mineral deficiency may affect nail development • Medication – Growth rate may be affected by medication • Climate – Hot climates increase growth • Damage – Matrix damage affects growth • Lifestyle – Chemical/detergent exposure Pathologies pg’s 181 - 183 • Ridges & Furrows • Nail becoming smaller • Pitting (Onychatrophia) • White Spots (Leuconychia) • Spoon-shaped Nail (Koilonychia) • Brittle Nails (Onychorrhexis) • Ingrowing Nails (Onychocryptosis) • Hang Nail • Bitten Nails (Onychophagy) • Discoloured Nails • Onchoptosis • Flaking (Lamella Dystrophy) • Onychia • Overgrowth of the Cuticle (Pterygium) • Ringworm • Excessive Thickening (Onychauxis) • Athletes Foot (Tinea Pedis) • Enlarged Nail with increases curve • Paronychia (Whitlow) (Onychogryphosis) • Psoriasis Hair Hair • Hair grows in Follicles which are located in the Dermis which is connected to the blood supply, nerves & lymphatic system Hair Follicle • Rooted in the Dermis & travel through the Epidermis to the surface of the skin • Erector Pili muscles are attached to the follicle & help to control body temperature by pulling the hair upright in cold temperatures. This traps a layer of warm air next to the skin Hair Sebaceous Glands • Each hair follicle has a Sebaceous Gland which produces Sebum, a fatty acid which moisturises the skin to keep it soft & supple • Sweat & Sebum combine on the surface of the skin to form the Acid Mantle which protects the skin from bacterial overgrowth by maintaining PH (4.5-5.6) Hair Structure • Cuticle – The Outer layer which consists of overlapping, transparent, Keratin Scales • Cortex – The Middle layer which consists of elongated cells which contain the pigment Melanin which gives hair its colour • Medulla – The Centre of the hair, composed of loosely connected keratinised cells Hair Structure of the Follicle • There are 4 layers in the follicle • Inner Root Sheath – This layer includes 3 sub-layers: Henle’s layer which is 1 cell thick, Huxley’s layer which is 2 or more cells thick & the Cuticle which interlocks with the cuticle of the hair • Outer Root Sheath – This layer lies outside the inner root sheath & forms the follicle wall. It is a continuation of the growing layer of the Epidermis • Vitreous Membrane – This separates the connective tissue from the outer root sheath • Connective Tissue – Surrounds the Follicle & Sebaceous Gland, providing the nerve & blood supply. The Dermal Papilla supplies the Follicle with nourishment for growth Types of Hair Lanugo • The baby in the uterus begins to develop soft, fine downy hair all over the body from about 3 months gestation • This hair begins to grow at the same time & grow at the same rate • It normally sheds 1 month before birth but premature babies may still have it Vellus • The follicles that produce Vellus hairs have no sebaceous glands • They are distributed over most of the body except – the soles of the feet, palms of the hands, lips & nipples • Pale in colour & only grow 1-2 cm in length Terminal Hair • Produced by hair follicles with Sebaceous Glands • It grows on the head, areas of the face, under arms & pubic area • Congenital/Genetic influence may affect Terminal hair growth, resulting in baldness & areas of hair resembling Vellus hair Hair Growth Cycle • Hair growth has 3 stages. Most hair is a dead shaft of Keratin. Hair grows from its base in the follicle – The Hair Bulb, for many years and then falls out • Hair growth then resumes production of a new hair • The Hair growth cycle incorporates the Anagen, Catagen & Telogen Phases Hair Growth Stages Anagen • The Growing phase. Can last 2-7 years. Hair grows at about 1cm per month • The hair bulb generates the pigment Melanin which gives the hair its colour • The length of the Anagen phase is determined by genetics Catagen • The Resting (intermediate) phase. Can last 2-4 weeks • The bulb produces neither hair cells nor pigment. It shrinks slightly, becoming less deep Telogen • A new hair begins to grow. It lasts about 3 months. The old hair will be shed naturally through brushing & washing • The new hair grows from the follicle & out of the skin – ready to begin its own Anagen Phase Factors affecting Hair Growth Cycle • Hormonal, Dietary, Environmental & Hereditary factors affect hair growth • Stress & Changes in Androgen (Male) Hormones especially affect hair growth • Female Hormones slow hair growth & extend the growing phase of the cycle • Puberty affects the pattern of terminal hair growth during the transition to Adulthood • Pregnancy, Menopause & ill-health all affect hair growth Teeth The Teeth • Teeth perform Mechanical Digestion • Act as a set of tools in digestion • 32 teeth in total ➢Incisors - straight narrow edges for biting ➢Canines - eye teeth - tear food ➢Molars & Premolars - for crushing & chewing Structure of Teeth • Teeth are embedded in the Alveoli (sockets) of the Alveolar Ridges in the Mandible & Maxilla of the Jaw Structure of Teeth • Crown – Visible part of the tooth above the gum line which is covered by Enamel • Root – Lower part of the tooth below the gum line extending into the jaw bone • Incisors/Canines – 1 single Root • Molars – 1/2/3 roots depending on location • Small opening at the end of the root called the Apical Foramen • Blood Vessels & Nerves pass through this opening into the tooth Structure of Teeth • Neck – The narrow region where the Crown meets the root at the gum line • Enamel – The hard outer shell of the Crown. It is hard wearing but easily damaged. It does not heal as bone repairs • Cementum – Covers the root of the tooth. It is not as hard as enamel and not as white. It helps to secure the tooth into the alveolus with tiny fibres in the Jaw bone • Dentin – A bone-like substance found under the layer of Cementum which makes up most of the tooth Structure of Teeth • Pulp & Pulp Cavity – The Pulp Cavity is located below the Dentin • The Pulp Cavity contains Nerves, Blood Vessels & Connective Tissue. This supplies the tooth with nutrients • Parts of the Pulp pointing upwards towards the points of the tooth (cusp) are called Pulp Horns • The Pulp Canal (Root Canal) is located in the root of the tooth Structure of Teeth Pulp Canal (Root Canal) • The open space inside the root is the Root Canal. It is connective tissue containing Blood Vessels & Nerves • Damage from infection/inflammation to the root canal will result in the tooth having a reduced supply of nutrients • Root canal repair may be required to save the tooth from extraction Structure of Teeth • Blood Supply – The Maxillary Arteries branch off to supply the teeth with oxygenated blood. Veins drain into the Internal Jugular Veins to remove Co2 & Waste • Nerve Supply – Maxillary nerves supply the upper teeth and Mandibular nerves supply the lower teeth • Both nerves are branches of the Trigeminal Nerve • The opening in the root tip embedded into the Alveolus of the bone is the Apical Foramen Tooth Disorders Plaque Gingivitis • A soft, clear substance which collects • Formation of a bio-film by bacteria to on the surface of the teeth.
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