Posterior forearm Flashcards
Muscles of posterior forearm rule
3 to wrist
3 to fingers
3 to thumb
What are all these muscles supplied by?
Radial nerve (superficial and deep/posterior interosseus branch)
2 muscles not to forget about
Aconeus (elbow stability)
Brachioradialis (on border of anterior and posterior, thumb side)
3 wrist muscles
Extensor carpi radialis longus
extensor carpi radialis brevis
extensor carpi ulnaris
3 finger muscles
extensor digitorum communis
extensor digit minimi
extensor indicis
3 thumb muscles
extensor pollucis longus
extensor pollucis brevis
abductor pollucis longus
Function posterior forearm
extensors
What do the thumb muscles create?
Anatomical snuff box
Origin for all posterior forearm
Lateral epicondyle (common extensor origin)
Brachioradialis O and I
O: lateral supracondylar ridge
I: Distal radius
brachioradialis A and I
A: flexes at elbow when mid prone (beer drinking)
I: Radial nerve
Extensor carpi radialis (longus and brevis)
O: supracondylar ridge humerus
I: longus: dorsal base of 2nd metacarpal
brevis: same but third metacarpal base
A: extends and abduct at the wrist
Extensor digitorum communis
O: lateral epi
I: extensor expansions
A: extends fingers at interphalangeal and metacarpophalangeal joints
How 4 tendons linked of EDC?
Juncturae tendinum (fibrous bands) prevents extension of middle/ring finger if other fingers are flexed
Extensor digiti minimi
I: extensor hood of little finger
A: extends little finger and wrist
Extensor carpi ulnaris
O: humeral head: lateral epi
ulnar head: olecranon
I: base of 5th metacarpal
A: adduction and extension of wrist
Deep muscles posterior arm
Supinator
Abductor pollucis longus
Extensor pollucis longus and brevis
Extensor indicis
Superficial posterior arm muscles
Brachioradialis Extensor carpi radialis (longus and brevis) Extensor carpi ulnaris Extensor digitorum Extensor digiti minimi Aconeus
Abductor pollucis longis O and I
O: interosseus membrane of radius and ulna
I: base of 1st metacarpal
abductor pollucis longus A and I
A: Abducts the thumb and extension at carpometacarpal joint
I: radial nerve (posterior interosseus)
Extensor pollucis longus O and I
O: posterior ulna and interosseus membrane
I: Distal phalanx of thumb
A: extends thumb at all joints
I: radial nerve
extensor pollucis brevis
O: posterior radius and interosseus membrane
I: proximal phalanx
A: extends thumb (NOT AT interphalangeal joints)
I: radial nerve (posterior interosseus)
Extensor indicis
O: posterior ulna and interosseus membrane
I: extensor hood index finger
A: extends index finger independently from others
I: radial nerve (posterior interosseus)
Branches radial nerve
Long and lateral triceps brachii
posterior cutaneous arm
Lower lateral cutaneous nerve of arm
posterior cutaneous nerve of forearm
Final branches radial nerve
Deep motor branch
Superficial sensory branch - dorsal lateral 3 digits
When does radial nerve change name and what to?
Through supinator to posterior compartment = posterior interosseus nerve
Whats anatomical snuff box?
Created by thumb muscles
Ulna border - extensor pollucis longus
radial border - abductor pollucis longus and extensor pollucis brevis
floor - scaphoid and trapezium
Snuff box isss?
Has radial artery and cephalic vein inside
Radial nerve over top
Scaphoid bone fracture can be palpated here (easy to miss on x-ray)
