B22 - Hoof, horn

Question 1

Hoof (eq)

Structures to mention

Answer 1

• Fascies articularis
• Fascies articulari sesamoidea
• Fascies parietalis
• Pars medialis
  
  • ​Sulcus parietalis medialis (eq)
  • Proc. palmaris medialis (eq)
    
    • For. proc. palmaris medialis (eq)
    • Inc. proc. palmaris medialis (eq)
• Pars lateralis
  
  • ​Sulcus parietalis lateralis (eq)
  • Proc. palamris lateralis (eq)
    
    • For. proc. palmaris lateralis (eq)
  • Inc. proc. palmaris lateralis (eq)
• Facies solearis
  
  • ​Facies flexoria (eq, sus)
  • Linea semilunaris (eq)
  • Planum cutaneum (eq, bo, sus)
  • Sulcus solearis medialis (eq)
  • Sulcus solearis lateralis (eq)
  • For. soleare mediale (eq)
  • For. soleare laterale (eq)
  • Canalis solearis (eq)
• Margo coronalis
  
  • ​Proc. extensorius
• Margo solearis
  
  • ​Crena marginis solearis (eq)
• Cart. ungularis medialis (eq)
• Cart. ungularis lateralis (eq)
• Ossa sesamoidea proximalia
• Os sesamoidea distale

Question 2

Hoof (eq)

What is the hoof composed of?

Answer 2

• Distal part of middle phalanx
• Distal interphalangeal joint
• Distal phalanx
• Distal sesamoid bone
• Terminal portion of digital flexor- and extensor tendons

Question 3

Hoof (eq)

Shape

Answer 3

• Angle toe makes with ground
  
  • Forelimb: 45-50˚
  • Hindlimb: 50-55˚
• Ratio between length of wall to height of heels:
  
  • Forelimb. 3:1
  • Hindlimb: 2:1
• Quarters descend to ground more steeply on medial side
• Sole of front hooves are more circular than hind hooves (egg-shape)

Question 4

Hoof (eq)

Division of wall

Answer 4

• Pars dorsalis (​Toe)
• Pars lateralis & pars medialis (​Quarters/sides)
• Pars mobilis lateralis & pars mobilis medialis (​Heels)
• Pars inflexia lateralis & pars inflexia medialis (​Bars)

Question 5

Hoof (eq)

Ground surface

Answer 5

• Margo solearis
• Sikea cornea
• Cuenus corners (frog)
• Torus corners (bulb of heels)

Question 6

Hoof (eq)

Segments

Answer 6

• 3 proximal segements:
  
  • Perioplic (limbus)
  • Coronary (corona)
  • Wall (paries)

Question 7

Hoof (eq)

Suspension of distal phalanx

Answer 7

• Suspended within horn capusle by dermis and epidermis of proximal segements that form hoof wall → are united with periosteum of bone

Question 8

Hoof (eq)

Biomechanics

Answer 8

• Force acting on distal phalanx are transmitted to wall of hoof → trigger hoof mechanicm
• Proximal part of wall is retracted inward, while heels spread
• Sole flattens → frog broadens

Question 9

Hoof (eq)

Layers

Answer 9

• Subcutis:
  
  • ​Ø wall or sole
  • Makes foot pad in limbus and coronary segments → shock absorbes
• Dermis:
  
  • ​Pododerma
  • Divided into:
    
    • Deep papillary layer → dermal papillae
    • Superficial reticular layer
• Epidermis:
  
  • _​_Cutal layers
    
    • ​Stratum basale
    • Stratum spinosum
    • Stratum granulosum
  • ​Horn layer:
    
    • ​Stratum corneum

Question 10

Hoof (eq)

Blood supply

Answer 10

• Aa. digitalis palmaris /plantaris lateralis + medialis
• Aa. digitalis communis plantages
  
  • Rr. tori digitalis
  • A. coronalis lateralis + medialis
  • Arcus terminalis

Question 11

Hoof (eq)

Innervation

Answer 11

Forelimb:

• N. mediana
  
  • ​N. digitalis palmaris communis
    
    • ​N. digitalis palmaris lateralis + medialis
      
      • R. tori

Hindlimb:

• N. tibialis
  
  • ​N. digitalis dorsalis communis
• N. fibularis profunda
  
  • ​N. metatarsea dorsalis lateralis + medialis

Question 12

Hoof (eq)

Draw the hoof

Answer 12

Question 13

Hoof

Name and draw the types of germinal layering

Answer 13

1. Papillary
   
   1. ​Producing columnar horn
2. Lamellar
   
   1. ​Producing lamellar horn

Question 14

Horn

General

Answer 14

• Bony core enclosed in modification of common inernment (horn sheeth)
  
  • Skeletal component: proc. cornualis os frontale
  • Horn sheath formed by horn epidermis
  • Horn:
    
    • Base
    • Body
    • Apex
• Found in both sexes in domestic mammals
• Permanent and grow constantly in domestic mammals

Question 15

Horn

Horn in bovine

Answer 15

• Proc. cornuales
  
  • ​Starts to pneumatise from 6 month of age
    
    • Invension of mucosal lining of sinus frontales into proc. cornualis
    • Continues until all bone is hollow, except for apex
• Horn sheath
  
  • ​Cornual subcutis
    
    • ​Ø subcutis in horn
    • Dermis directly adhere to bone - stable junction between horny enclosure and proc. cornualis
  • Cornual dermis
    
    • ​Distinct papillae
      
      • ​Parallel to dermal surface in base and body
      • More erect towards apex
  • Epidermis
    
    • ​Form tubular horn
    • Growth of horn predominantly at base, and pushes old layers apically

Question 16

Horn

Horn in small ruminants

Answer 16

• Parietal position closer to orbits
• Ov: helical
• Cap: grow caudally
• Proc. cornuales originates from separate ossification center (os corneal)
  
  • ​Maxes secondary fusion to os frontale
• X-section:
  
  • Ov: triangular
  • Cap: oval shape

Question 17

Horn

Blood supply

Answer 17

Arterial:

• A. temporalis superficialis
  
  • ​Aa. cornuales

Venous:

• Vv. cornuales
  
  • ​V. temporalis superficialis

Question 18

Horn

Innervation

Answer 18

• N. trigemini (V)
  
  • N. zygomaticotemporalis
    
    • ​R. cornualis

Clinical importance: anaesthesia for dehorning