posterior Forearm Muscles

Question 1

Superficial

Answer 1

Origin: * Extensor Carpi Radialis Longus:
Above lateral epicondyle of humerus
* All others: Lateral epicondyle of
humerus (CEO)

Insertion:
* ECRL: Base of second metacarpal
* ECRB: Base of third metacarpal *
ED: Distal phalanx of digits 2-5 via
extensor expansion
* ECU: Base of fifth metacarpal

Actions: * All: extension of wrist and elbow
* ECRL: Abducts wrist * ECRB: Abducts wrist * ED: Finger extension (digits 2-5) * ECU: Adducts wrist (or hand)

Question 2

Deep origin

Answer 2

• Supinator: CEO, the posterior radial notch of
  ulna
• Anconeus: CEO
• Abductor pollicis longus (APL): posterior
  surface of radius & ulna, interosseous
  membrane
• Extensor pollicis longus (EPL): Posterior
  surface of ulna; interosseous membrane
• Extensor pollicis brevis (EPB): Posterior
  surface of radius; interosseous
  membrane
• Extensor Indicis (EI): posterior surface of
  ulna; interosseous membrane

Answer 3

Insertions: * Supinator: Anterolateral radius, distal to radial
tuberosity
* Anconeus: Olecranon
* APL: First metacarpal * EPL: Distal phalanx of thumb
* EPB: Proximal phalanx of thumb
* EI: Distal phalanx of digit 2 (via extensor
expansion)
Actions: * Supinator: Forearm supination, elbow extension
* Anconeus: Elbow extension
* APL: Wrist extension; thumb abduction
* EPL: MCP/IP extension of thumb; wrist extension
* EPB: MCP extension of thumb; wrist extension
* EI: IP extension 2nd digit; wrist extensio