A19 - Digital extensors and flexors of the forelimb

Question 1

Which muscles should be mentioned in the topic?

Answer 1

Extensors of the forelimb phalanges:

1. M. extensor carpi radialis
2. M. extensor carpi ulnaris
3. M. extensor digitorum communis
4. M. extensor digitorum lateralis
5. M. extensor digiti I et II (Ca)
6. M. abductor digiti 1 longus

Flexors of the forelimb phalanges:

1. M. flexor digitalis superficialis
2. M. flexor digitalis profundus
   
   • Caput humerale
   • Caput ulnare
   • Caput radiale
3. M. flexor carpi radialis
4. M. flexor carpi ulnaris
   
   • Caput humerale
   • Caput ulnare
5. M. interflexorii (ø eq)
6. M. interossei
7. M. flexor digitalis brevis

Question 2

Give the extensors of the forelimb phalanges

Answer 2

1. M. extensor carpi radialis
2. M. extensor carpi ulnaris
3. M. extensor digitorum communis
4. M. extensor digitorum lateralis
5. M. extensor digiti I et II (Ca)
6. M. abductor digiti 1 longus

Question 3

M. extensor carpi radialis

Answer 3

• Origin: Crista supracondylaris lateralis of humerus
• Insertion: Mc 2-3
• Action: Extend carpus
• Innervation:
  
  • N. radialis
    
    • r. profundus
    • r. superficialis (med/lat)
    • r. cutaneus antebrachii lateralis

Question 4

M. extensor carpi ulanris

Answer 4

• Origin: Epicondylus lateralis of humerus
• Insertion:
  
  • ​Lateral on Mc 5
  • A**ccessory carpal bone
• Action:
  
  • ​Abducts and lateral rotation of the carpal joint
  • Extends the carpal joint
• Innervation:
  
  • N. radialis
    
    • r. profundus
    • r. superficialis (med/lat)
    • r. cutaneus antebrachii lateralis

Question 5

M. extensor digitorum communis

Answer 5

• Origin: Epicondylus lateralis of humerus
• Insertion: Ph3, digits 2-5
• Action: Extends carpus and digits 2-5
• Innervation:
  
  • N. radialis
    
    • r. profundus
    • r. superficialis (med/lat)
    • r. cutaneus antebrachii lateralis

Question 6

M. extensor digitorum lateralis

Answer 6

• Origin: Epicondylus lateralis of humerus
• Insertion: Ph2/3 of digit 3-5
• Action: Extends carpus and digits 3-5
• Innervation:
  
  • N. radialis
    
    • r. profundus
    • r. superficialis (med/lat)
    • r. cutaneus antebrachii lateralis

Question 7

M. extensor digiti I et II

Answer 7

Ca​

• Origin: Middle third of ulna
• Insertion: Digits 1 and 2
• Action: Extends digits 1 and 2, indicis adducts dew claw
• Innervation:
  
  • N. radialis
    
    • r. profundus
    • r. superficialis (med/lat)
    • r. cutaneus antebrachii lateralis

Question 8

M. abductor digiti I longus

Answer 8

• Origin: Ulna on lateral border and cranial surface
• Insertion: Proximal end of Mc 1
• Action: Abducts and extends digit 1
• Innervation:
  
  • N. radialis
    
    • r. profundus
    • r. superficialis (med/lat)
    • r. cutaneus antebrachii lateralis

Question 9

Give the flexors of the forelimb phalanges

Answer 9

1. M. flexor digitalis superficialis
2. M. flexor digitalis profundus
   
   • Caput humerale
   • Caput ulnare
   • Caput radiale
3. M. flexor carpi radialis
4. M. flexor carpi ulnaris
   
   • Caput humerale
   • Caput ulnare
5. M. interflexorii (ø eq)
6. M. interossei
7. M. flexor digitalis brevis

Question 10

M. flexor digitorum superficialis

Answer 10

• Origin: Epicondylus medialis of humerus
• Insertion: Ph2 of digit 2-5
• Action: Flexes carpus and digits 2-5
• Innervation: N. medianus
• Its insertion tendon divides for the major digits:
  
  • Dog: Into 4
  • Cat: Into five
  • Eq: Undivided
  • Ru. sus: Into two

Question 11

M. flexor digitorum profundus

Answer 11

• Origin:
  
  • ​Caput humerale: epicondylus medialis of the humerus
  • Caput radiale: middle third of the radius
  • Caput ulnare: medial aspect of olecranon
• Insertion: Ph3 or digit 1-5 (palmar)
• Action:
  
  • ​Flexes the carpus and all the digits
  • Un: helps fixing the fetlock joint
• Innervation:
  
  • N. ulnaris
    
    • r. cutaneous antebrachii caudalis

Question 12

M. flexor carpi radialis

Answer 12

• Origin: Epicondylus medialis of humerus
• Insertion: Mc 2-3 (palmar)
• Action: Flex carpus
• Innervation: N. medianus

Question 13

M. flexor carpi ulnaris

Answer 13

• Origin:
  
  • ​Caput ulnare: Olecranon on caudal border and medial surface
  • Caput humerale: Epicondylus medialis of humerus
• Insertion: Accessory carpal bone
• Action: Flexes the carpus
• Innervation: (same as m. flexor digitorum profundus)
  
  • ​N. ulnaris
    
    • r. cutaneous antebrachii caudalis

Question 14

Mm. interflexorii

Answer 14

Ø eq

Binds the bellies or tendons of the superficial and deep flexors together

Question 15

M. flexord digitalis brevis

Answer 15

Car

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

Question 16

Give the short muscles of the digits

Answer 16

• Divide into
  
  1. Common short muscles of the digits
     
     • M. interossei
     • Mm. lumbricales (ø ru)
     • M. flexor digitalis brevis (ca)
  2. Special short muscles of the digits (mainly in carnivores, activates the movement of induvidual muscles)
     
     • 1st digit:
       
       • M. flexor pollicis brevis
       • M. abductor pollicis brevis
       • M. adductor pollicis
     • 2nd digit:
       
       • M. adductor digiti II
     • 5th digit:
       
       • M. flexor digiti V
       • M. assuctor digiti V
       • M. abductor digit V