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Abductor pollicis brevis muscle: want to learn more about it?

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Abductor pollicis brevis muscle

Abductor pollicis brevis muscle (Musculus abductor pollicis brevis)

The muscles of thenar are a group comprised of four muscles; abductor pollicis brevis, adductor pollicis, flexor pollicis brevis, and opponens pollicis. They form an elevation located on the radial (lateral) aspect of the palm, named the thenar eminence.

Abductor pollicis brevis is the most lateral and the most superficial of thenar muscles, located underneath the skin. It runs from the scaphoid and trapezium bones, and from the flexor retinaculum to the proximal phalanx of thumb.

The main function of abductor pollicis brevis is the abduction of the thumb at the carpometacarpal joint.

In this article, we will discuss the anatomy and function of the abductor pollicis brevis muscle.

Key facts about the abductor pollicis brevis muscle
Origin Tubercles of scaphoid and trapezium bones, Flexor retinaculum
Insertion Lateral aspect of base of proximal phalanx 1 (via radial sesamoid bone)
Action Carpometacarpal joint 1: Thumb abduction
Innervation Recurrent branch of median nerve (C8, T1)
Blood supply Superficial palmar branch of radial artery

Origin and insertion

Abductor pollicis brevis originates from several locations. The majority of muscle fibers originate from the broadest origin area located on flexor retinaculum. Two smaller origins are located on carpal bones; the first is found on the tubercle of scaphoid while the second is on the tubercle of trapezium bone.

After originating from these locations, the muscle fibers form a single muscle belly that runs distally and radially (lateral) towards the thumb. Near the insertion, the muscle ends in a flat tendon that inserts onto the radial aspect of the base of the proximal phalanx of thumb. Lateral slips of the tendon join the expansion of extensor pollicis longus tendon.

Relations

Abductor pollicis brevis is a fusiform muscle located at the surface of the thenar eminence, directly superior to opponens pollicis and flexor pollicis brevis muscles. These three muscles comprise a gap through which the thenar branch of median nerve passes. The superficial palmar branch of radial artery runs across the superficial aspect of abductor pollicis brevis.

Innervation

Abductor pollicis brevis is innervated by the recurrent (thenar) branch of median nerve (root value C8 and T1).

Blood supply

Abductor pollicis brevis is vascularized by the superficial palmar branch that arises from the radial artery.

Function

The main action of abductor pollicis brevis muscle is the abduction of thumb at the carpometacarpal and metacarpophalangeal joints. This action happens in synergy with abductor pollicis longus muscle. Abductor pollicis brevis also facilitates the movement of the thumb towards the fingertips in the carpometacarpal joint (opposition) and flexion in the metacarpophalangeal joint. All of the aforementioned functions of this muscle are of great significance for the proper functioning of the hand, such as grasping round objects or carrying out tasks that demand precision (e.g. writing and sewing).

Abductor pollicis brevis muscle: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 1,300,460 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
  • Palastanga, N., & Soames, R. (2012). Anatomy and human movement: structure and function (6th ed.). Edinburgh: Churchill Livingstone.
  • Standring, S. (2016). Gray's Anatomy (41tst ed.). Edinburgh: Elsevier Churchill Livingstone.
  • Netter, F. (2014). Atlas of Human Anatomy (6th ed.). Philadelphia, PA: Saunders.

Illustrations:

  • Abductor pollicis brevis muscle (Musculus abductor pollicis brevis) - Yousun Koh
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