Opponens pollicis muscle

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Opponens pollicis muscle
1121 Intrinsic Muscles of the Hand Deep LD.png
The deep muscles of the right hand. Palmar surface.
1121 Intrinsic Muscles of the Hand Superficial sin.png
The superficial muscles of the left hand. Palmar surface.
Details
Origin trapezium and transverse carpal ligament
Insertion metacarpal bone of the thumb on its radial side
Artery Superficial palmar arch
Nerve Recurrent branch of the median nerve
Actions Flexion of the thumb's metacarpal at the first carpometacarpal joint, which aids in opposition of the thumb
Identifiers
Latin Musculus opponens pollicis
TA A04.6.02.058
FMA 37379
Anatomical terms of muscle
[edit on Wikidata]

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.

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. https://nervesurgery.wustl.edu/ev/upperextremity/median/thenarbranch/Pages/OpponensPollicis.aspx

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 (yes, with an 'a') the bones (bring them toward each other).

Additional images

References

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

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