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| | ===Equine Hoof=== | | ===Equine Hoof=== |
| − | <font color ="red">The horny material encasing the distal phalanx is known as the '''hoof'''. It is continuous with the skin at the coronary region. The hoof can be divided into three topographical regions; the '''wall''', the '''frog''' and the '''sole'''. The '''wall''' forms the medial, lateral and dorsal aspect of the hoof. It can be further divided into the '''toe''', '''quarters''' and '''heels'''. At the heel the walls reflect back on themselves at a point called the '''angles''' and in doing so forms the '''bars'''. The bars fade out before they meet cranially. The '''frog''' sits between the bars and has an apex facing dorsally, with 2 crura flanking a central sulcus. Between the crus and bar of each half lies the '''collateral sulcus'''. Opposite the apex the frog expands forming the '''bulbs of the heel'''. The '''sole''' is the area dorsal to the bars and apex of the frog enclosed by the hoof wall. The area where the bars and wall enclose it is known as the '''angle of the sole'''.
| + | [[image: X-section through hoof.jpg|thumb|200px|right|A X-section through a typical hoof. ©Rachael Wallace2008]] |
| | + | As outlined above, the equine hoof can be divided into three topographical regions; the '''wall''', the '''frog''' and the '''sole'''. The '''wall''' forms the medial, lateral and dorsal aspect of the hoof. It can be further divided into the '''toe''', '''quarters''' and '''heels'''. At the heel the walls reflect back on themselves at a point called the '''angles''' and in doing so forms the '''bars'''. The bars fade out before they meet cranially and run along the edge of the frog within the sole. The '''frog''' sits between the bars and has an apex facing dorsally, with 2 crura flanking a central sulcus. Between the crus and bar of each half lies the '''collateral sulcus'''. Opposite the apex the frog expands forming the '''bulbs of the heel'''. The '''sole''' is the area dorsal to the bars and apex of the frog enclosed by the hoof wall. The area where the bars and wall enclose it is known as the '''angle of the sole'''. |
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| | A well-trimmed foot should weight bear on its walls, bars and frog. This occurs as the weight applied to the distal phalanx is then transferred across the interdigitating laminae to the hoof wall. Thus an injury resulting in damage to the laminae is of extreme importance to the horse. | | A well-trimmed foot should weight bear on its walls, bars and frog. This occurs as the weight applied to the distal phalanx is then transferred across the interdigitating laminae to the hoof wall. Thus an injury resulting in damage to the laminae is of extreme importance to the horse. |
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| − | The epidermis of the horny hoof is termed the '''coronary epidermis'''. Its surface has a plantar aspect and newly formed hoof grows distally towards the plantar surface of the structure. Hoof wall is generally 5 - 10 mm in thickness and consists of 3 layers:
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| − | * A thin outer layer or "'''wall'''" of shiny, dense horn, which effectively seals the hoof against dehydration and penetration.
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| − | * A thicker, intermediate layer of '''amorphorous''' horn, interspersed with '''tubular horn''' which provides reinforcement. This layer makes up the bulk of the hoof.
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| − | * An inner, lamellar layer, where epidermis and dermis interdigitate, anchoring the dead portion of the hoof to the living surface of the third phalanx.
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| − | [[image: X-section through hoof.jpg|thumb|200px|right|A X-section through a typical hoof. ©Rachael Wallace2008]]
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| − | The pigmentation in the outer layer of hooves is derived from melanocytes in the coronary epidermis. Deeper layers contain little melanin and therefore appear lightly coloured or white. The unpigmented layer of keratin forms a '''white line''' on the sole of the hoof, which delineates the sole from the wall when the solar surface is viewed.
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| | [[image: Plantar hoof aspect.jpg|thumb|175px|left|A view of the solar surface of an equine hoof. The wall has been removed on the right to show the underlying dermis. ©Rachael Wallace2008]] | | [[image: Plantar hoof aspect.jpg|thumb|175px|left|A view of the solar surface of an equine hoof. The wall has been removed on the right to show the underlying dermis. ©Rachael Wallace2008]] |
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| − | The keratin in the sole is formed by the epidermis of the plantar aspect of the third phalanx and reaches a maximum thickness of 1 cm. It is less resistant to abrasion than that of the outer layer of the hoof. The central '''frog''' of the sole of a horse is located between the sharply inflected '''bars''' of the wall and is softer and less rigid than the keratin of the wall of the hoof. Its elasticity is particulary important in the horse as pressure on the frog changes the angle of the walls when the horse stands on that foot. The change in angle, termed the '''hoof mechanism''' increases the blood circulation in the hoof, increasing the supply of nutrients to the coronary epidermis. This is closely correlated to hoof wall quality.
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| − | A band of soft, pliable horn termed the '''periople''' (analagous with the cuticle of human nails) lies over the proximal outer surface of the wall. This band widens at the back of the hoof to also cover the '''bulbs of the heels''' and part of the '''frog'''.
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| | For further detail see the [[Equine Phalanges - Anatomy & Physiology|equine phalanges]] page. | | For further detail see the [[Equine Phalanges - Anatomy & Physiology|equine phalanges]] page. |
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