Abductor Pollicis Brevis Muscle Anatomy

The abductor pollicis brevis (APB), the short abductor of the thumb, forms the anterolateral part of the thenar eminence.

The thenar eminence of the hand is made up of four muscles:

• The abductor pollicis brevis muscle,
• The opponens pollicis muscle,
• The adductor pollicis muscle,
• The flexor pollicis brevis muscle.

Abductor Pollicis Brevis Muscle Anatomy

The abductor pollicis brevis origin is from the front of transverse carpal ligament, extending into the tubercles of scaphoid and trapezium with an occasional contribution from the tendon of abductor pollicis longus. It inserts onto the radial side of the base of the proximal phalanx of the thumb.

This muscle is innervated by the recurrent branch of the median nerve C8, T1, and gets its blood supply from the Superficial palmar branch of the radial artery.

In addition to abducting the thumb, the abductor pollicis brevis assists the opponens pollicis during the early stages of opposition by rotating its proximal phalanx slightly medially.

See Also: Hand Anatomy, Bones & Muscles

To test the abductor pollicis brevis, abduct the thumb against resistance. If acting normally, the muscle can be seen and palpated.

References & More

1. Cael, C. (2010). Functional anatomy: Musculoskeletal anatomy, kinesiology, and palpation for manual therapists. Philadelphia, PA: Wolters Kluwer Health/Lippincott, Williams & Wilkins.
2. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
3. Clinically Oriented Anatomy – 8th Edition
4. NAPIER JR. The attachments and function of the abductor pollicis brevis. J Anat. 1952 Oct;86(4):335-41. PMID: 12999637; PMCID: PMC1273687. Pubmed