Muscle
Adductor pollicis
Brings the thumb inward for a firm pinch
High-yield
Thumb adduction relies on the deep ulnar nerve branch, even though many other thenar movements use the median nerve.
Overview
Two muscle heads converge deep in the palm to pull the thumb toward the hand. This ulnar-supplied muscle helps hold an object between the thumb and index finger.
Reference facts
- Origin
- Oblique head: capitate and second/third metacarpal bases; transverse head: palmar surface of the third metacarpal
- Insertion
- Ulnar side of the thumb's proximal phalanx at its base
- Action
- Draws the thumb toward the palm and supports pinch
- Innervation
- Deep ulnar nerve branch, mainly C8–T1
- Blood supply
- Branches of the deep palmar arterial arch
Clinical correlation
When thumb adduction is weak, flexor pollicis longus may compensate during a pinch by bending the thumb's interphalangeal joint. This is Froment's sign, a finding that can support an assessment of ulnar nerve dysfunction.
Frequently asked questions
What does the adductor pollicis do?
The adductor pollicis draws the thumb toward the palm and supports pinch.
What nerve innervates the adductor pollicis?
Deep ulnar nerve branch, mainly C8–T1.
Where does the adductor pollicis attach?
Origin: Oblique head: capitate and second/third metacarpal bases; transverse head: palmar surface of the third metacarpal. Insertion: Ulnar side of the thumb's proximal phalanx at its base.
What is the blood supply of the adductor pollicis?
Branches of the deep palmar arterial arch.