Posterior Muscles of Forearm Flashcards
What muscles extend and abduct or adduct the hand at the wrist joint?
Extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris
What muscles extend the medial four digits?
Extensor digitorum, extensor indicis, and extensor digiti minimi
What muscles extend or abduct the thumb?
Abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus
What is the origin of the brachioradialis?
Proximal two thirds of lateral supraepicondylar ridge of humerus
Where does the brachioradialis insert?
Lateral surface of distal end of radius proximal to styloid process
What is the innervation of the brachioradialis?
Radial nerve (C5, C6, C7)
What action does the brachioradialis perform?
Relatively weak flexion of elbow joint, maximal when forearm is in mid pronated position
What is the origin of the extensor carpi radialis longus?
Lateral supra-epicondylar ridge of humerus
Where does the extensor carpi radialis longus insert?
Dorsal aspect of base of 2nd metacarpal
What is the innervation of the extensor carpi radialis longus?
Radial nerve (C6, C7)
What action does the extensor carpi radialis longus perform?
Extend and abduct wrist joint
What is the origin of the extensor carpi radialis brevis?
Lateral epicondyle of the humerus
Where does the extensor carpi radialis brevis insert?
Dorsal aspect of base of 3rd metacarpal
What is the innervation of the extensor carpi radialis brevis?
Deep branch of radial nerve (C7, C8)
What action does the extensor carpi radialis brevis perform?
Extend and abduct wrist joint, active during fist clenching
What is the origin of the extensor digitorum?
Lateral epicondyle of humerus
Where does the extensor digitorum insert?
Extensor expansions of medial four fingers
What is the innervation of the extensor digitorum?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the extensor digitorum perform?
Extends wrist joint and medial four fingers primarily at metacarpophalangeal, secondarily at interphalangeal joints
What is the origin of the extensor digiti minimi?
Lateral epicondyle of humerus
Where does the extensor digiti minimi insert?
Extensor expansion of 5th finger
What is the innervation of the extensor digiti minimi?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the extensor digiti minimi perform?
Extends wrist joint and 5th finger primarily at metacarpophalangeal, secondarily at interphalangeal joint
What is the origin of the extensor carpi ulnaris?
Lateral epicondyle of humerus; posterior border of ulna via shared aponeurosis
Where does the extensor carpi ulnaris insert?
Dorsal aspect of base of 5th metacarpal
What is the innervation of the extensor carpi ulnaris?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the extensor carpi ulnaris perform?
Extends and adducts wrist joint, also active during fist clenching
What is the orign of the supinator?
Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator fossa, crest of ulna
Where does the supinator insert?
Lateral, posterior and anterior surfaces of proximal third of radius
What is the innervation of the supinator?
Deep branch of radial nerve (C7, C8)
What action does the supinator perform?
Supinates forearm
What is the origin of the abdcutor pollicis longs?
Posterior surface of proximal halves of ulna, radius, and interosseous membrane
Where does the abductor pollicis longus insert?
Base of 1st metacarpal
What is the innervation of the abductor pollicis longs?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the abductor pollicis longus perform?
Extends wrist joint and abducts thumb and extends it at carpometacarpal joint
What is the origin of the extensor pollicis longus?
Posterior surface of middle third of ulna and interosseous membrane
Where does the extensor pollicis longus insert?
Dorsal aspect of base of distal phalanx of thumb
What is the innervation of the extensor pollicis longus?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the extensor pollicis longus perform?
Extends wrist joint and distal phalanx of thumb at interphalangeal joint, also extends metacarpophalngeal and carpometacarpal joints
What is the origin of the extensor pollicis brevis?
Posterior surface of distal third of radius and interosseous membrane
Where does the extensor pollicis brevis insert?
Dorsal aspect of base of proximal phalanx of thumb
What is the innervation of the extensor pollicis brevis?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the extensor pollicis brevis perform?
Extends wrist joint and proximal phalanx of thumb at metacarpophalangeal joint, alsoe extends carpometacarpal joint
What is the origin of the extensor indicis?
Posterior surface of distal third of ulna and interosseous membrane
Where does the extensor indicis insert?
Extensor expansion of 2nd finger
What is the innervation of the extensor indicis?
Posterior interosseous nerve (C7, C8); continuation of deep branch of radial nerve
What action does the extensor indicis perform?
Extends wrist joint and 2nd finger, also helps extend hand at wrist
