A15 - The horse’s artt. interphalangeae proximalis et distalis of the forelimb and their muscles

Question 1

What is another name for:

1. Art. interphalangeae proximalis
2. Art. interphalangeae distalis

Answer 1

1. Art. interphalangeae proximalis = Pastern joint
2. Art. interphalangeae distalis = coffin joint

Question 2

Pastern joint

Answer 2

• Saddle joint (diaxial)
  
  • ​Movement: flexion - extension (minimal rotation and side movements)
• Proximal interphalageal joint
• Between: Ph1 → Ph2

Structures:

• ​Capsulae articulares
  
  • ​Recessus dorsales
  • Recessus palmares
• Ligg. collateralia
  
  • ​Two collateral ligaments of each joint
• Ligg. palmaria
  
  • ​Ru, su: on the 3^rd and 4^th digits
  • Eq: 4 palmar ligaments:
    
    • Axial
    • Abaxial
    • Lateral
    • Medial
• Scutum medium is composed of:
  
  • Lig. axiale
  • Straight sesamoidean ligamet
  • Palmar surface of the flexor surface of Ph2

Question 3

Coffin joint

Answer 3

• Saddle joint (diaxial)
  
  • ​Movement: flexion - extension (minimal side movements)
• Art. composita (also include distal sesamoid bones)
• Between:
  
  • Distal end of Ph2
  • Ph3
  • Articular surface of distal sesamoid bone/navicular bone
• Retinaculum flexorum
• Bursa podotrochlearis
• ​Os sesamoidea distale → m. flexor digitorum profundus, tendon

Structures

• Capsulae articulares
  
  • ​Recessus dorsales
  • Recessus caudales
• Ligg. collateralia
  
  • ​2 collateral ligaments of each joint capsule
• Ligg. dorsalia
  
  • ​2 elastic dorsal ligaments of each joint
• Ligg. sesamoidea collateralia (eq, bo)
  
  • Os sesamoideum distale → Ph2
• ​Lig. sesamoideum distale impar (eq)
  
  • Os sesamoideum distale → Ph 3
• Lig. interdigitale proximale (bo, su)
  
  • Between proximal phalanges of digit III and IV
• Lig. chondrocompedalia (un)
  
  • Cartilage ungularis → Ph1
• Lig. chondrocoronalia (un)
  
  • Cartilage ungularis → Ph2
• Ligg. chondrosesamoidea (Un)
  
  • Cartilago ungularis → os sesamoideum distale
• Ligg. chondroungularia collateralia (Un)
  
  • Cartilago ungularis → processus palmaris of the same side (medial or lateral)
• Ligg. chondroungularia cruciata (Un)
  
  • Extends from cartilago ungularis of one side to that of the other side and to the opposite processus palmaris

Ligaments of the distal sesamoid bone / navicular bone:

• ​Ligg. sesamoideum collateralia (eq, bo)
• Lig. sesamoideum distale impar (eq)

Ligaments of the hoof cartilage:

• Ligg. chondrocompedalia
• Ligg. chondrocoronalia
• ​Ligg. chondroungularia collateralia
• ​Ligg. chondrosesamoidea
• ​Ligg. chondroungularia cruciata

Question 4

Draw the phalangeal joints of the horse and the bovine

Answer 4

Question 5

Retinaculum flexorium

Answer 5

• Transverse fibers on the palmar aspext at the level of the carpal joint
• Retinaculum extensorium: corresponding structure on dorsal side
• On the palmar side, the sheat comprice:
  
  • Lig. anulare palmare
    
    • ​Surrounding flexor tendons
  • Fetlock plate
    
    • ​Cartilage plate attached to Ph1, unites flexor tendons to Ph1
  • Ligg. annularia digit
    
    • ​Sheet forming a “sock” around flexor tendons

Question 6

Give the muscles of the forelimb phalanges

Answer 6

Digital extensors of the forelimb (craniolateral):

• M. extensor digitorum communis
• M. extensor digitorum lateralis
• M. extensor digiti I. et II. [pollicis et indicis] (ca)
• M. abductor digiti I. [pollicis] longus

Digital flexors of the forelimb (mediocaudally):

• M. flexor digitorum superficialis
• M. flexor digitorum produndus
  
  • ​Caput humerale
  • Caput radiale
  • Caput ulnare
• Mm. interflexorii (ø eq) (On hindlimb, only in ca)
• M. interossei
• Mm. lumbricales (ca)
• M. flexor digitalis brevis (ca)

Question 7

M. extensor digitorum communis

Answer 7

• Origin: Epicondylus lateralis of humerus
  
  • Eq: Caput radiale
• ​Insertion:
  
  • Ca: Processus extensorius of Ph3, digit 2-5
  • Eq: Ph1 (with m. extensor digitorum lateralis
• Action: Extends carpus and joints of digits
• Innervation: N. radialis

Question 8

M. extensor digitorum lateralis

Answer 8

• Origin:
  
  • Ca:
    
    • Epicondylus lateralis of humerus
    • Lateral collateral ligament
  • ​Eq: Radius and ulna, proximal
• Insertion:
  
  • Dog:
    
    • Goes to digits III-V., at the level of first digit it unites with tendons from m. extensor digitorum communis and m. interosseous
    • Inserts on Ph3, processus extensorius
  • ​Eq:
    
    • Ph1, proximal (with m. extensor digitorum communis)
• Action:
  
  • Ca: Extend carpus and joints of digits 3, 4 and 5
  • Eq: Extends carpus
• Innervation: N. radialis
• Tendon of insertion splits in
  
  • Dog: 3 → goes to digits 3,4 and 5
  • Cat: 4 → 2nd to 5th digits
  • Eq: 1 → 3rd digit, attached on proximal phalanx
  • Ru: 1 → 4th digit, attached on 2nd phalanx
  • Sus: 2 → 4th and 5th digit

Question 9

M. extensor digiti I. et II. [pollicis et indicis]

Answer 9

Ca

• Origin: Middle third of ulna (laterally)
• Insertion:
  
  • Pollicis: Mc 1, head
  • Indicis: unites with m. extensor digitorum communis, together inserts on Ph3 of digit 2
• Action:
  
  • Extends digits 1-2
  • Indicis adducts dew claw
• Innervation: N. radialis

Question 10

M. abductor digiti I. [pollicis] longus

Answer 10

• Origin:
  
  • Ca:
    
    • Adjacent lateral surface of radius and ulna
    • From interosseous membrane
  • Eq: Middle of radius, craniolateral
• Insertion: Mc, base (medially)
  
  • Ca: Mc 1
  • Eq, su : Mc 2
  • Ru: Mc 3
• Action:
  
  • Ca: extends and abducts digit 1
  • Other animals: extend the carpal joint
• Innervation: N. radialis

Question 11

M. flexor digitorum superficialis

Answer 11

• Origin: Epicondylus medialis of humerus
• Insertion: Ph2, palmar surface
  
  • Dog: digits 2-5
• Action:
  
  • Ca: To flex the carpus and affected joints of digits II-V
  • Eq:
    
    • Flex digits and carpus
    • Extends elbow joint
• Innervation:
  
  • ​Ca: N. medianus
  • Eq: N. ulnaris
• Its insertion tendon divides for the major digits:
  
  • Dog: Into 4
  • Cat: Into 5
  • Eq: Undivided
  • Ru. sus: Into 2

Question 12

M. flexor digitorum profundus

Answer 12

• Three heads of origin:
  
  • Caput humerale: epicondylus medialis of the humerus
  • Caput radiale: radius, caudal surface
  • Caput ulnare: olecranon, medial
• Insertion:
  
  • Ca: Ph3 of digits 1-5, palmar on tuberculum flexorium
  • ​Eq: Ph3, facies flexoria
• Action:
  
  • Flexes carpus and joints of digits
  • Extends elbow joint (eq)
• Innervation:
  
  • ​N. ulnaris
  • N. medianus (ca)
• Vagina synovialis communis mm. flexorium: around the flexor tendons, at the level of the carpus

Question 13

Mm. interflexorii

Answer 13

Ø eq

Small muscular or tendinous bundles which binds the bellies or tendons of the superficial and deep flexors together

Question 14

M. interossei

Answer 14

• Origin: Proximal part of the metacarpals
• Insertion:
  
  • Ca: On the sesamoid bones of the first digital joint
  • Eq: Proximal sesamoid bones
• Action:
  
  • To flex the metacarpalphalangeal joint of the supporting digits in ca and sus
  • Eq: counteracts overextension of fetlock joint (suspensory ligament)
• Innervation:
  
  • ​N. ulnaris

Question 15

Mm. lumbricales

Answer 15

Ca

• Action: To flex the first digital joint

Question 16

M. flexor digitalis brevis

Answer 16

Ca

• Origin: M. flexor digitorum superficialis
• Insertion: Digit 5
• Action: To assist in flexing the digit(s)

Question 17

Give the special short muscles

Answer 17

• Activates the movement of the induvidual digits
• Mainly in carnivores

1^st digit:

• M. flexor pollicis brevis
• M. abductor pollicis brevis
• M. adductor pollicis

2^nd digit:

• M. adductor digiti II

5^th digit:

• M. flexor digiti V
• M. assuctor digiti V
• M. abductor digiti V