Test 2 Posterior Forearm Muscles Flashcards
Brachioradialis proximal attachment , origin
proximal 2/3 of lateral supraepicondylar ridge of humerus
superficial layer
- Brachioradialis
- Extensor carpi radialis longus
- extensor carpi radialis brevis
- extensor digitorum
- extensor digiti minimi
- extensor carpi ulnaris
Brachioradialis distal attachment insertion
lateral surface of distal end of radius proximal to styloid process
Brachioradialis innervation
radial nerve C5 C6 C7
Brachioradialis action
weak flexion of forearm, maximal when forearm is in mid pronated position
extensor carpi radialis longus proximal attchment origin
lateral supra epicondylar ridge of the humerus
extensor carpi radialis longus distal attachment insertion
dorsal aspect of base of 2nd metacarpal
extensor carpi radialis longus innervation
radial nerve C6 C7
extensor carpi radialis longus action
-extend and abduct hand at wrist joint
extensor carpi radialis brevis proximal attachment origin
lateral epicondyle of the humerus
extensor carpi radialis brevis distal attachment insertion
dorsal aspect of base of 3rd metacarpal
extensor carpi radialis brevis innervation
deep branch of radial nerve C7 C8
extensor carpi radialis brevis action
- extends and abducts hand at wrist
- active during fist clenching
extensor digitorum proximal attachment origin
lateral epicondyle of humerus
extensor digitorum distal attachment insertion
extensor expansion of medial four fingers
extensor digitorum innervation
posterior interosseous nerve C7 C8 = continuation of deep radial nerve
extensor digitorum action
- extends medial four fingers primarily at metacrpophalangeal joints
- secondarily at interphalangeal joints
extensor digiti minimi proximal attachment origin
lateral epicondyle of humerus
extensor digiti minimi distal attachment insertion
extensor expansion of 5th finger
extensor digiti minimi innervation
posterior interosseous nerve C7 C8 = continuation of deep branch of radial nerve
extensor digiti minimi action
- extends fifth finger primarily at metacarpophalangeal joint
- secondarily at interphalangeal joint
extensor carpi ulnaris proximal attachment origin
- lateral epicondyle of humerus
- posterior border of ulna via a shared aponeurosis
extensor carpi ulnaris distal attachment insertion
dorsal aspect of the base of the 5th metacarpal
extensor carpi ulnaris innervation
posterior interosseous nerve C7 C8 =continuation of deep branch of radial nerve
extensor carpi ulnaris action
- extends and adducts hand at wrist joint
- also active during fist clenching
deep layer of posterior forearm muscles
supinator
supinator proximal attachment origin
- lateral epicondyle of humerus
- radial collateral and annular ligaments
- supinator fossa
- crest of ulna
supinator distal attachment insertion
lateral posterior and anterior surfaces of proximal 1/3 of radius
supinator innervation
deep branch of radial nerve C7 C8
supinator action
- supinates forearm
- rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)
“outcropping” muscles of deep layer
posterior forearm
- abductor pollicis longus
- extensor pollicis longus
- extensor pollicis brevis
- extensor indicis
abductor pollicis longus proximal attachment origin
posterior surface of proximal halves of ulna, radius, and interosseous membrane
abductor pollicis longus distal attachment insertion
base of 1st metacarpal
abductor pollicis longus innervation
posterior interoseous nerv C7 C8 = continuation of deep branch of radial nerve
abductor pollicis longus action
- abducts thumb
- extends thumb at the carpometacarpal joint
extensor pollicis longus proximal attachment origin
posterior surface of middle 1/3 of ulna and interosseous membrane
extensor pollicis longus distal attachment insertion
dorsal aspect of base of distal phalanx of thumb
extensor pollicis longus innervation
posterior interosseous nerve C7 C8 = continuation of deep branch of radial nerve
extensor pollicis longus action
- extends distal phalanx of thumb at interphalangeal joint
- extends metacarpophalangeal and carpometacarpal joints
extensor pollicis brevis proximal attachment origin
posterior surface of distal 1/3 of radius and interosseous membrane
extensor pollicis brevis distal attachment insertion
dorsal aspect of base of proximal phalanx of thumb
extensor pollicis brevis innervation
posterior interosseous nerve C7 C8 = continuation of the deep branch of radial nerve
extensor pollicis brevis action
- extends proximal phalanx of thumb at metacarpophalangeal joint
- extends carpometacarpal joint
extensor indicis proximal attachment origin
-posterior surface of distal 1/3 of ulna and interosseous membrane
extensor indicis distal attachment insertion
extensor expansion of 2nd finger
extensor indicis innervation
posterior interoseous nerve C7 C8 = continuation of deep branch of radial nerve
extensor indicis action
- extends 2nd finger (enabling its independent extension)
- helps extend hand at wrist
