Abductor pollicis brevis - Upper extremity - Muscles of upper limb - e-Anatomy
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Abductor pollicis brevis

Abductor brevis pollicis

  • Latin synonym: Musculus abductor pollicis brevis
  • Synonym: Abductor pollicis brevis muscle
  • Acronym: APB

Definition

Muhammad A. Javaid

Abductor pollicis brevis

Origin

Flexor retinaculum, scaphoid, trapezium.

Insertion

Base of the proximal phalanx (radial side), extensor expansion.

Innervation

Median nerve (recurrent branch) C8, T1

Action

Abduction of the thumb

Antagonist

Adductor pollicis muscle

Origin

The abductor pollicis brevis muscle is an intrinsic thenar muscle of the hand. It originates primarily from the flexor retinaculum (transverse carpal ligament) and the tubercle of the scaphoid bone, with some fibers also coming from the trapezium.

Insertion

Its muscle fibers extend distally and laterally, inserting into the lateral aspect of the base of the proximal phalanx of the thumb and its extensor hood.

Innervation

Like the other two thenar muscles, the abductor pollicis brevis is innervated by the recurrent branch of the median nerve.

Action

Functionally, the abductor pollicis brevis is the primary abductor of the thumb at the carpometacarpal and metacarpophalangeal joints. This action moves the thumb away from the palm, perpendicular to its surface, making the muscle essential for opposition and precision grip.

References

  • Okwumabua E, Sinkler MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Hand Muscles. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537229/

  • Loss J, Li ZM. Biometry of thenar muscle origins on the flexor retinaculum. Clin Anat. 2020 Nov;33(8):1176-1180.

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