Adductor Pollicis
Hand · Upper Limb
The adductor pollicis is a deep, triangular muscle of the palm with two heads: an oblique head from the bases of the second and third metacarpals and the capitate, and a transverse head from the shaft of the third metacarpal. The two heads converge onto the medial base of the proximal phalanx of the thumb. It adducts the thumb, drawing it back toward the plane of the palm, an action essential for a firm pinch grip. It is supplied by the deep branch of the ulnar nerve (C8, T1); its weakness produces a positive Froment's sign, where the thumb flexes to compensate when gripping paper.
Origin, Insertion, Action & Nerve
Origin
Oblique head: bases of 2nd–3rd metacarpals and capitate; Transverse head: anterior shaft of 3rd metacarpal
Insertion
Medial base of proximal phalanx of thumb
Action
Adduction of thumb
Nerve
Deep branch of ulnar nerve (C8, T1)
Attachments explained
The Adductor 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
Oblique head: bases of 2nd–3rd metacarpals and capitate; Transverse head: anterior shaft of 3rd metacarpal
Insertion
Medial base of proximal phalanx of thumb
Action & function
When the Adductor Pollicis contracts, it produces the following movement: Adduction of thumb.
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 Adductor Pollicis receives its nerve supply from the Deep branch of ulnar 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 Deep branch of ulnar nerve or to its spinal roots (C8, T1) can weaken or paralyse the Adductor Pollicis, impairing the movements it normally produces (adduction of thumb). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Adductor Pollicis (the OIANS method)
Contrast adductor pollicis directly with abductor pollicis brevis: one pulls the thumb back toward the palm, the other pushes it away, and the two are supplied by different nerves. Its two heads converging on the medial base of the thumb's proximal phalanx give it the power behind a pinch grip.
Its signature clinical test is Froment's sign: with the ulnar nerve damaged, adductor pollicis cannot hold a sheet of paper, so the thumb bends at its tip using the median-supplied flexor pollicis longus instead. Remembering that this is the one thenar-region thumb muscle on the ulnar nerve prevents the common mix-up.
Frequently asked questions
Where is the Adductor Pollicis located?
The Adductor Pollicis is a muscle of the Hand group, located in the Upper Limb.
What is the origin of the Adductor Pollicis?
Oblique head: bases of 2nd–3rd metacarpals and capitate; Transverse head: anterior shaft of 3rd metacarpal
What is the insertion of the Adductor Pollicis?
Medial base of proximal phalanx of thumb
What movements does the Adductor Pollicis produce?
Adduction of thumb
What nerve supplies the Adductor Pollicis?
Deep branch of ulnar nerve (C8, T1)
Is the Adductor Pollicis free to study in OIANS?
Yes. The Adductor 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 Adductor Pollicis
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