Download - Posterior Aspect of the Forearm
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In two layers:
a superficial layera deep layer.
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Common origin lateral
epicondyle of the humerus
Except for the
brachioradialis and
anconeus, extend as
tendons into the hand.
Brachioradialis
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris
Extensor digitorum
Extensor digiti minimi
Base of 2nd
metacarpal
Base of 3rd
metacarpalBase of 5th
metacarpal
Anconeus
Proximal part of
supraepicondylar ridge of
humerus
Lateral surface of distal
end of radius proximal
to styloid process
Distal part of supraepicondylar
ridge of humerus
Base of 2nd metacarpal
Lateral epicondyle of
humerus
common extensor origin
Base of 3
rd
metacarpals
Lateral epicondyle of
humerus
common extensor origin
Base of the 5th
metacarpal
Lateral epicondyle of
humerus
dorsal aspects of the
bases of the middle
and distal phalanges of
the medial four digits
Lateral
epicondyle of
humerus
Extensor
expansion
(hood) ofthe 5thdigit
Lateral epicondyle
of humerus
Olecranon and proximal
posterior surface of ulna
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Except for the supinator muscle, all these deep layer muscles originate from the
posterior surfaces of the radius, ulna, and interosseous membrane and pass into
the thumb and fingers.
Supinator
Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus
Extensor indicis
Superficial (humeroulnar) head
lateral epicondyle of
humerus
radial collateral and anular
ligaments
Deep (ulnar) headSupinator crest of the ulna
Lateral surface of radius
superior to the anterior
oblique line
Posterior surface of proximal
halves of ulna, radius, and
interosseous membrane
Base of 1st
metacarpal
Posterior surface of middle third of ulna and
interosseous membrane
Dorsal surface of base of distal phalanx of thumb
Posterior surface of distal third of radius and
interosseous membrane
Dorsal surface of base of proximal phalanx of the
thumb
Posterior surface of
distal 1/3 of ulna
and
interosseous
membrane
Extensor
expansion
(hood) of 2nd
digit
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Muscle Main Action
Brachioradialis Relatively weak flexion of forearm; maximal when forearm is in
midpronated position; an accessory of flexor of the elbow joint
Extensor carpi
radialis longus(ECRL)
Extend and abduct hand at the wrist joint; ECRL active during fist
clenching
Extensor carpi
radialis brevis
(ECRB)
Extensor
digitorum Extends medial four digits primarily at metacarpophalangeal joints,secondarily at interphalangeal joints ; can also extend the wrist
Extensor digiti
minimi (EDM)
Extends the little finger
Extensor carpi
ulnaris (ECU)
Extends and adducts hand at wrist joint (also active during fist
clenching)
Anconeus Abduction of the ulna in pronation; accessory extensor of the elbow
joint; assists triceps in extending forearm
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Muscle Muscle Action
Supinator Supinates forearm; rotates radius to turn palm anteriorly or superiorly (if
elbow is flexed)
Extensor indicis Extends 2nd digit (enabling its independent extension); helps extend hand
at wrist
Abductor
pollicis longus
(APL)
Abducts carpometacarpal joint of thumb; accessory extensor of the thumb
Extensor
pollicis longus
(EPL)
Extends distal phalanx of thumb at interphalangeal joint; extends
metacarpophalangeal and carpometacarpal joints
Extensor
pollicis brevis
(EPB)
Extends proximal phalanx of thumb at metacarpophalangeal joint; extends
carpometacarpal joint
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Brachioradialis
Extensor carpi radialis longus
Radial nerve Main nerve)
Supinator
Extensor carpi radialis brevis
Deep branch of radial nerve
Rest
Posterior interosseous nerve
continuation of deep branch ofradial nerve
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Radial artery
Posterior interosseous
artery
origin:
common interosseous branch of
the ulnar artery
recurrent interosseous artery
nd by joining to dorsal
carpal arch of the wrist
Anterior interosseous
artery
origin:
common interosseous branch of
the ulnar artery
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Deep branch becomes posterior interosseous nerve
after emerging from between 2 heads of supinator
Posterior interosseous nerve
passes deep to extensor pollicis longus to reach
the wrist.
http://www.jaaos.org/content/19/7/430/F4.expansionhttp://www.jaaos.org/content/19/7/430/F4.expansion -
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Deep branch becomes posterior interosseous nerve
after emerging from between 2 heads of supinator