Muscle
Flexor pollicis brevis
Short thumb flexor with variable nerve supply
High-yield
The superficial part usually receives median fibers; the deep part often receives ulnar fibers. Treat this as a common pattern, because dual and alternative supplies occur.
Overview
Situated at the thumb base, this muscle mainly bends the metacarpophalangeal joint. Its superficial and deep parts vary in their attachments and in how the median and ulnar nerves supply them.
Reference facts
- Origin
- Superficial part: trapezium and flexor retinaculum; deep part: mainly trapezoid and capitate
- Insertion
- Usually the radial base of the thumb's proximal phalanx through the radial sesamoid; deep slips can vary
- Action
- Primarily bends the thumb at its MCP joint
- Innervation
- Usually recurrent median supply superficially and deep ulnar supply to the deep part; the pattern varies
- Blood supply
- Radial artery branches supplying the thenar region
Frequently asked questions
What does the flexor pollicis brevis do?
Primarily bends the thumb at its MCP joint.
What nerve innervates the flexor pollicis brevis?
Usually recurrent median supply superficially and deep ulnar supply to the deep part; the pattern varies.
Where does the flexor pollicis brevis attach?
Origin: Superficial part: trapezium and flexor retinaculum; deep part: mainly trapezoid and capitate. Insertion: Usually the radial base of the thumb's proximal phalanx through the radial sesamoid; deep slips can vary.
What is the blood supply of the flexor pollicis brevis?
The flexor pollicis brevis is supplied by the radial artery branches supplying the thenar region.