Lecture 2: Outcropping Muscles of deep layer of posterior compartment

What are the three muscles are form the outcropping

-Abductor pollicis longus -Extensor pollicis brevis -Extensor pollicis longus

Abductor pollicis longus: origin (3), insertion, nerve, action (2)

-Origin: posterior and proximal half of ulna, radius, and interosseous membrane -Insertion: base of 1st metacarpal -Nerve: Posterior interosseous nerve C7, C8 (deep branch radial nerve) -Action: Abducts thumb (w/ APB), extends thumb at carpometacarpal joint (EPL and EPB)

Extensor Pollicis brevis: origin (2), insertion, innervation, action (4)

-Origin: posterior surface of distal 1/3rd of radius and interosseous membrane -Insertion: dorsal aspect of base of proximal phalanx of thumb -Nerve: Posterior interosseous nerve C7, C8 (deep branch radial n) -Action: extend proximal phalanx of thumb at metacarpophalalgeal joint, extend carpometacarpal joint, extend and abduct hand

Extensor pollicis longus: origin (2), insertion, nerve, action (4)

-Origin: posterior surface of middle 1/3rd of ulna and interosseous membrane -Insertion: dorsal aspect of base of distal phalanx of thumb -Nerve: Posterior interosseous nerve C7,C8 (deep branch radial nerve) -Action: extend thumb distal phalanx at interphalangeal joint, extend metacarpophalangeal and carpometacarpal joints, adduct extended thumb and rotates it laterally

What muscles uses the dorsal tubercle as a pulley to change its line of pull

Extensor pollicis longus