Opponens pollicis muscle

The opponens pollicis is a small, triangular muscle in the hand, which functions to oppose the thumb. It is one of the three thenar muscles, lying deep to the abductor pollicis brevis and lateral to the flexor pollicis brevis.

Opponens pollicis muscle
The deep muscles of the right hand. Palmar surface.
The superficial muscles of the left hand. Palmar surface.
Details
Origintrapezium and transverse carpal ligament
Insertionmetacarpal bone of the thumb on its radial side
ArterySuperficial palmar arch
NerveRecurrent branch of the median nerve
ActionsFlexion of the thumb's metacarpal at the first carpometacarpal joint, which aids in opposition of the thumb
Identifiers
LatinMusculus opponens pollicis
TAA04.6.02.058
FMA37379
Anatomical terms of muscle

Structure

The opponens pollicis originates from the flexor retinaculum of the hand and the tubercle of the trapezium. It passes downward and laterally, and is inserted into the whole length of the metacarpal bone of the thumb on its radial side.

Innervation

Like the other thenar muscles, the opponens pollicis is innervated by the recurrent branch of the median nerve. In 20% of the population, opponens pollicis is innervated by the ulnar nerve.[1]

Blood supply

The opponens pollicis receives its blood supply from the Superficial palmar arch.

Function

Apposition of the thumb is a combination of actions that allows the tip of the thumb to touch the tips of other fingers. The part of apposition that this muscle is responsible for is the flexion of the thumb's metacarpal at the first carpometacarpal joint. This specific action cups the palm. Many texts, for simplicity, use the term opposition to represent this component of true apposition. In order to truly appose the thumb, the actions of a number of other muscles are needed at the thumb's metacarpophalangeal joint. Note that the two opponens muscles (opponens pollicis and opponens digiti minimi) are named so because they oppose each other, but their actions appose the bones.

Additional images
  • The muscles of the thumb
  • The muscles of the right hand. Palmar surface.
  • Opponens pollicis muscle
  • Bones of the left hand. Volar surface.
  • Transverse section across the wrist and digits.
  • Muscles of hand. Cross section.

References
  1. "Opponens Pollicis (OP)". Washington University School of Medicine. Retrieved 2019-07-19.

This article incorporates text in the public domain from page 461 of the 20th edition of Gray's Anatomy (1918)

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