Abductor Pollicis Longus (APL) Anatomy

Origin: Middle third of the posterior surfaces of the ulna and radius, and the interosseous membrane.

Insertion: Base of the first metacarpal bone of the thumb.

Innervation: Posterior interosseous nerve.

Nerve: Radial nerve (via posterior interosseous nerve branch)

Diagrams & Photos
  • Abductor Pollicis Longus (APL)
    Abductor Pollicis Longus (APL)
  • Note the APL tendon exiting the fascia of the first extensor compartment, passing over the radial artery (yellow arrow), and inserting into the base of the thumb metacarpal at the forceps' tip.
    Note the APL tendon exiting the fascia of the first extensor compartment, passing over the radial artery (yellow arrow), and inserting into the base of the thumb metacarpal at the forceps' tip.
Key Points
  • Abductor Pollicis Longus (APL) typical has 2 to 7 slips. 
  • The multiple slips are frequently seen when opening the first dorsal extensor compartment during surgical release of the compartment for DeQuervain's tenosynovitis. 
  • The Abductor Pollicis Longus (APL) makes the palmar border of the anatomic snuff box of the scaphoid.
Anatomy References
Anatomic Abbreviations
Hand Surgery Resource Anatomy Diagnostic Guide (Chapter)