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==Introduction==

==Introduction==

The hoof is defined from a physiologic perspective as the modified skin [[Skin - Anatomy & Physiology#Epidermis|(epidermis)]] covering the tip of the digit and all enclosed structures. The hoof provides protection to the distal limb and is formed by keratinisation of the epithelial layer and modification of the underlying dermis. The keratin in the [[Skin - Anatomy & Physiology#Epidermis|epidermis]], when thickened and cornified, is referred to as [[Horn - Anatomy & Physiology|horn]].  Horn makes up the outer surface if the hoof and is particularly resistant to mechanical and chemical damage.

The hoof is defined from a physiologic perspective as the modified skin [[Skin - Anatomy & Physiology#Epidermis|(epidermis)]] covering the tip of the digit and all enclosed structures. The hoof provides protection to the distal limb and is formed by keratinisation of the epithelial layer and modification of the underlying dermis. The keratin in the [[Skin - Anatomy & Physiology#Epidermis|epidermis]], when thickened and cornified, is referred to as [[Horn - Anatomy & Physiology|horn]].  Horn makes up the outer surface if the hoof and is particularly resistant to mechanical and chemical damage.

===Periople===

===Periople===

The periople is a small band of soft tissue found over the proximal surface of the wall of the hoof. The periople represents the junction between the wall and the skin of the limb. The periople is responsible for the production of the outer layer of the wall (above). The periople segment extends around the proximal edge of the wall and in horses covers the bulb of the heel and part of the frog. In ruminants is forms part of the join between both hooves of the foot.  The perioplic corium, proximal to the coronary band and continuous with the skin, it produces the thin, shiny layer (stratum externa) of the hoof wall.

The periople is a small band of soft tissue found over the proximal surface of the wall of the hoof. The periople represents the junction between the wall and the skin of the limb. The periople is responsible for the production of the outer layer of the wall (above). The periople segment extends around the proximal edge of the wall and in horses covers the bulb of the heel and part of the frog. In ruminants it forms part of the join between both hooves of the foot.  The perioplic corium, proximal to the coronary band and continuous with the skin, it produces the thin, shiny layer (stratum externa) of the hoof wall.

==Deeper structures of the foot==

==Deeper structures of the foot==

[[File:Horse_hoof_wild_bare_sagittal.jpg|thumb|200px|right|Saggital section through horse hoof.]]

[[File:Horse_hoof_wild_bare_sagittal.jpg|thumb|200px|right|Sagittal section through horse hoof.]]

Enclosed within the hoof capsule are the bony structures – the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]], distal end of the [[Phalanges_-_Horse_Anatomy#Middle_Phalanx|middle phalanx]], the [[Joints_and_Ligaments_-_Horse_Anatomy#Distal_Interphalangeal_.28Coffin.29_Joint|distal interphalangeal joint]], and the [[Phalanges_-_Horse_Anatomy#Distal_Sesamoid_.28Navicular.29_Bone|distal sesamoid bone (navicular)]].  There are also soft tissue structures including ligaments, cartilage, the digital cushion and the insertions of the [[Tendons_-_Horse_Anatomy#Thoracic_Limb|common digital extensor tendon]] and the [[Tendons_-_Horse_Anatomy#Flexorsdeep|digital flexor tendon]].

Enclosed within the hoof capsule are the bony structures – the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]], distal end of the [[Phalanges_-_Horse_Anatomy#Middle_Phalanx|middle phalanx]], the [[Joints_and_Ligaments_-_Horse_Anatomy#Distal_Interphalangeal_.28Coffin.29_Joint|distal interphalangeal joint]], and the [[Phalanges_-_Horse_Anatomy#Distal_Sesamoid_.28Navicular.29_Bone|distal sesamoid bone (navicular)]].  There are also soft tissue structures including ligaments, cartilage, the digital cushion and the insertions of the [[Tendons_-_Horse_Anatomy#Thoracic_Limb|common digital extensor tendon]] and the [[Tendons_-_Horse_Anatomy#Flexorsdeep|digital flexor tendon]].

===Ungual (collateral) cartilages===

===Ungual (collateral) cartilages===

The ungual cartilages are extensions of the distal phalanx (Plll) that extend caudally and dorsally from the medial and lateral margins of Plll, curving inwards towards each other in the heel region.  The cartilages extend just beyond the confines of the hoof capsule making them palpable just above the coronary band at the lateral and medial edges of the foot.  The ungual cartilages can ossify resulting in ‘side bones’ which have the potential for fracturing.  The cartilages can also become infected resulting in the condition known as ‘quittor’.  

The ungual cartilages are extensions of the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]] (Plll) that extend caudally and dorsally from the medial and lateral margins of the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]], curving inwards towards each other in the heel region.  The cartilages extend just beyond the confines of the hoof capsule making them palpable just above the coronary band at the lateral and medial edges of the foot.  The ungual cartilages can ossify resulting in ‘side bones’ which have the potential for fracturing.  The cartilages can also become infected resulting in the condition known as ‘quittor’.

 

The cartilages are securely attached to the other internal structures of the foot by a series of ligaments that extend from the medial and lateral cartilages to the distal and middle phalanx, the [[Phalanges_-_Horse_Anatomy#Distal_Sesamoid_.28Navicular.29_Bone|distal sesamoid bone (navicular)]], and the digital cushion.

The cartilages are securely attached to the other internal structures of the foot by a series of ligaments that extend from the medial and lateral cartilages to the distal and middle phalanx, the navicular bone, and the digital cushion.

[[File:Lateral view hoof internal structures.jpg|thumb|Internal hoof structures]]

===Collateral ligaments.===

===Collateral ligaments.===

The distal interphalangeal joint is enclosed within the hoof capsule.  It is stabilised by the medial and lateral collateral ligaments which form part of the joint capsule, connecting the distal end of Pll with the proximal edge of Plll.

The distal interphalangeal joint is enclosed within the hoof capsule.  It is stabilised by the medial and lateral collateral ligaments which form part of the joint capsule, connecting the distal end of Pll with the proximal edge of the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]].

 

===Annular ligaments===

===Annular ligaments===

The annular ligament has its origins on the medial and lateral surfaces of distal Pl. It is the most superficial structure in the region, lying just beneath the skin and fusing with the DDFT where it enters the hoof capsule. Once inside the hoof the annular ligament merges with the fibrous attachments of the ungual cartilages and digital cushion, and continues with the DDFT down to its insertion onto Plll.

The annular ligament has its origins on the medial and lateral surfaces of distal Pl. It is the most superficial structure in the region, lying just beneath the skin and fusing with the [[Tendons_-_Horse_Anatomy#Flexorsdeep|digital flexor tendon]] where it enters the hoof capsule. Once inside the hoof the annular ligament merges with the fibrous attachments of the ungual cartilages and digital cushion, and continues with the [[Tendons_-_Horse_Anatomy#Flexorsdeep|digital flexor tendon]] down to its insertion onto the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]].

===Sesamoidean ligaments===

===Sesamoidean ligaments===

The dorsal border of the navicular bone is held securely to the palmar/plantar surface of the distal phalanx by the distal sesamoidean ligament and to the proximal phalanx via the proximal interphalangeal collateral ligaments by means of a pair of medial and lateral collateral sesamoidean ligaments.  

The dorsal border of the [[Phalanges_-_Horse_Anatomy#Distal_Sesamoid_.28Navicular.29_Bone|distal sesamoid bone (navicular)]] is held securely to the palmar/plantar surface of the [[Phalanges_-_Horse_Anatomy#Distal_Phalanx|distal phalanx]] by the distal sesamoidean ligament and to the proximal phalanx via the proximal interphalangeal collateral ligaments by means of a pair of medial and lateral collateral sesamoidean ligaments.  

===Navicular bursa===

===Navicular bursa===

The navicular bone (distal sesamoid bone) lies between the second and third phalanges and the deep digital flexor tendon.  Associated with it is a fluid-filled sac that reduces friction between the bone and the DDFT that lies over the top of it— the navicular bursa.  Inflammation in the region is involved in navicular disease which is a common cause of lameness.  

The [[Phalanges_-_Horse_Anatomy#Distal_Sesamoid_.28Navicular.29_Bone|distal sesamoid bone (navicular)]] lies between the middle and distal phalanges and the deep digital flexor tendon.  Associated with it is a fluid-filled sac that reduces friction between the bone and the [[Tendons_-_Horse_Anatomy#Flexorsdeep|digital flexor tendon]] that lies over the top of it— the navicular bursa.  Inflammation in the region is involved in navicular disease which is a common cause of lameness.  

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[[Category:Integumentary System - Anatomy & Physiology]]

[[Category:Integumentary System - Anatomy & Physiology]]

[[Category:A&P Done]]

[[Category:A&P Done]]