Nails

Published on 13th July 2018

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Structure and Function

Nails are derived from the same cells as the epidermis and hair and are made of hard keratinised dead cells. They provide protection for the ends of fingers and toes as well as helping us to manipulate small objects and to scratch an itch! 

 

At the base of the nail is the living matrix and the lunula  
 

Maxtrix is where the cells of the nail plate and nail bed are produced. The matrix produces Keratin cells for the nail plate and nail bed, pushing older cells forward along the toe or finger to form the nail plate. The dead nail plate is the part of the nail which lies on top of the skin or nail bed.    
 

Lunula the visible half moon shape  

Cuticle closely attached to the lunula is the cuticle which is a fold of skin forming a seal between the matrix and the plate, protecting the matrix from infection.  
 

Eponychium  
The eponychium forms a seal between the skin and the nail plate that protects the underlying matrix from infection  
 

Nail Plate  
The dead nail plate is the part of the nail which lies on top of the skin or nail bed. (commonly called fingernail /toenail). It is a protective shield of translucent keratin for the nail bed beneath

Nail bed  
This nail bed is rich in blood and lymph vessels as well as nerve fibres made up of 3 layers of cells held together with moisture and fat. The blood vessels give the nails their pinkish colour and you can assess the state of a persons circulation by lightly pressing down on a nail and then releasing to see how quickly the blood returns. In anaemia the nail bed would look very pale. 

Nail Fold  
The folds in the skin which protect the matrix and in which the edges of the nail plate sit  

Hyponchium  
The hyponchium forms a seal between the free edge of the nail and the skin of the fingertip

Nail bed

This nail bed is rich in blood and lymph vessels as well as nerve fibres made up of 3 layers of cells held together with moisture and fat. The blood vessels give the nails their pinkish colour and you can assess the state of a persons circulation by lightly pressing down on a nail and then releasing to see how quickly the blood returns. In anaemia the nail bed would look very pale. 

Nail Fold  
The folds in the skin which protect the matrix and in which the edges of the nail plate sit  

Hyponchium  
The hyponchium forms a seal between the free edge of the nail and the skin of the fingertip

Nail Growth

Just like hair, nails start to develop in the foetus- usually about month 4. And just like hair and skin, the growth occurs by the older cells pushing their way upwards to the surface and becoming keratinised as they move further away from their living, growing point. 
Nails grow approximately 3 mm a month –toenails take a little longer. The whole fingernail is replaced two to three times per year and the toenail every year to 18 months. Again like skin and hair, growth can be affected by many other factors such as nutrition, trauma or injury, hormones, age, medication, climate, damage and general health.

Pathologies of the nails

Nails can be prone to infections – mainly bacterial or fungal –which affects their growth and appearance. 

Onychosis

 is the technical term for a nail disease and comes from the Greek for nail or claw

Beau’s line

 deep horizontal depressions on all nails.  Possibly through trauma, diabetes or malnutrition 

Discoloured nails

Blue nail – poor circulation, anaemia or heart problem  
Black nail – bruised – nail may detach from the nail bed  
Stained – stained by a variety of things including nicotine, enamels, hair dyes

Brittle nails (Onychorrhexis)

Poor blood supply, caused by anaemia, illness or use overs-trong detergents removing natural oils. 

Flaking nails

Can be due to biting, incorrect or severe hand and nail treatments , lengthy exposure to hot water 

Kolionychia

Spoon shaped nails commonly associated with any condition which causes thinning of the nail. It is a spoon shape to the nail plate ie the centre of the nail hollows or dips to give a spoon shape when looked at from the side. It is most commonly seen in iron deficiency anaemia but may be hereditary.

Leukonchia  (white nails or spots) 

Abnormality in nail matrix (resulting from trauma, nail varnish, anaemia, renal disease, dermatitis, psoriasis) 

Onychauxis

Thick curved nail resulting from ill-fitted shoes, trauma, fungal infection, psoriasis 

Onychocryptosis

Ingrowing nails - mostly affecting the big toe. The side of the nail plate grows into the flesh of the nail wall. Mainly due to poor or excessive cutting or filing down of the nails or ill fitting shoes.

Onychophagy 

Bitten nails. Nail biting reduces the size of the nails so eventually it has no free edge.

Paronychia

Bacterial infection of the cuticle resulting in inflammation.

Pitting

Pitting or small dents in the nails can be a sign of an underlying problem such as dermatitis or psoriasis.

Pterygium (overgrowth of the cuticle)

The cuticle has a hardened growth which has grown over and stuck to the nail plate.

Tinea Unigium 

A fungal infection of the nails 

Tinea Pedis 

Athletes foot – a fungal infection 

Whitlow

 Is where the area of skin surrounding the nail is red and inflamed. This may be caused by a bacterial infection or else injury to the area. 

 

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