Opponens Pollicis
Hand · Upper Limb
The opponens pollicis is a deep thenar muscle central to the human capacity for opposition. It arises from the tubercle of the trapezium and the flexor retinaculum and inserts along the whole length of the radial border of the first metacarpal. Acting on the carpometacarpal joint, it opposes the thumb, flexing and medially rotating the first metacarpal so the thumb pad can meet the pads of the other fingers. It is supplied by the recurrent branch of the median nerve (C8, T1) and so is weakened in carpal tunnel syndrome.
Origin, Insertion, Action & Nerve
Origin
Tubercle of the trapezium and flexor retinaculum
Insertion
Whole length of the radial (lateral) border of the first metacarpal
Action
Opposes the thumb (flexes and medially rotates the first metacarpal)
Nerve
Recurrent branch of the median nerve (C8–T1)
Attachments explained
The Opponens Pollicis is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Tubercle of the trapezium and flexor retinaculum
Insertion
Whole length of the radial (lateral) border of the first metacarpal
Action & function
When the Opponens Pollicis contracts, it produces the following movement: Opposes the thumb (flexes and medially rotates the first metacarpal).
As part of the Hand group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Opponens Pollicis receives its nerve supply from the Recurrent branch of the median nerve (C8–T1). This nerve carries fibres from spinal segment(s) C8, T1.
Because a muscle can only contract when its nerve is intact, injury to the Recurrent branch of the median nerve or to its spinal roots (C8, T1) can weaken or paralyse the Opponens Pollicis, impairing the movements it normally produces (opposes the thumb (flexes and medially rotates the first metacarpal)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Opponens Pollicis (the OIANS method)
The name is the action: opponens pollicis produces opposition, the rotation and flexion of the first metacarpal that lets the thumb pad touch the fingertips. Note that it inserts on the whole metacarpal rather than a phalanx, which is why it rotates the entire thumb column rather than bending a single joint.
Opposition is the defining human hand movement, so its loss in carpal tunnel syndrome is functionally serious. Group it with the other thenar muscles on the recurrent branch of the median nerve, and remember that testing opposition (thumb pad to little-finger pad) checks this muscle and that nerve directly.
Frequently asked questions
Where is the Opponens Pollicis located?
The Opponens Pollicis is a muscle of the Hand group, located in the Upper Limb.
What is the origin of the Opponens Pollicis?
Tubercle of the trapezium and flexor retinaculum
What is the insertion of the Opponens Pollicis?
Whole length of the radial (lateral) border of the first metacarpal
What movements does the Opponens Pollicis produce?
Opposes the thumb (flexes and medially rotates the first metacarpal)
What nerve supplies the Opponens Pollicis?
Recurrent branch of the median nerve (C8–T1)
Is the Opponens Pollicis free to study in OIANS?
Yes. The Opponens Pollicis is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Opponens Pollicis
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