Extensors and Supinators of the antibrachium and manus

Question 1

extensor carpi radialis m.

Answer 1

origin: lateral supracondylar crest of the humerus (cat has two muscle heads)
insertion: dorsal surfaces of base of metacarpals 2 & 3 (cat - long tendon on MC 2, short tendon on MC 3)

Innervation: radial n.

actions: extension of the carpus, flexion of the elbow

Question 2

common digital extensor m.

Answer 2

origin: lateral epicondyle of the humerus
insertion: extensor processes of distal phalanges of digits 2-5
innervation: radial n.
action: extension of the carpus, extension of digits 2-5

Question 3

lateral digital extensor m.

Answer 3

origin:
dog - lateral epicondyle of the humerus
cat- lateral supracondylar ridge

insertion: joins the common digital extensor tendons

dog - extensor processes of distal and middle phalanges of digits 3-5
cat - extensor processes of distal and middle phalanges of digits 2-5

Innervation: radial n.

action: extension of the carpus, extension of the joints of digits 3-5

Question 4

extensor carpi ulnaris m.

Answer 4

origin: lateral epicondyle of the humerus

insertion:
Dog - proximal end of metacarpal 5 and accessory carpal bone
cat - MC 5

Innervation: radial n.

action: primarily supports the carpus (anti-hyperextender), abduction of the carpus

Question 5

abductor pollicis longis m.

Answer 5

origin: lateral border and cranial surface of the body of the ulna, interosseous membrane; also arises from the radius in the cat
insertion: proximal end of MC 1
innervation: radial n.
action: abduction of digit 1, extension of the carpus

Question 6

brachioradialis m. (dog)

Answer 6

origin: lateral supracondylar crest of the humerus
insertion: distal fourth of the radius
innervation: radial n.
action: supination of the antebrachium

Question 7

brachioradialis m. (cats)

Answer 7

origin: middle fifth of the humerus
insertion: styloid process of the radius
innervation: radial n.
action: supination of the antebrachium

Question 8

supinator m.

Answer 8

origin: lateral epicondyle of the humerus
insertion: cranial surface of the proximal fourth of the radius
innervation: radial n.
action: supination of the antebrachium, flexion of the elbow