The Probert Encyclopaedia of Medicine

FLEXOR POLLICIS BREVIS

The flexor pollicis brevis (thumb muscle) is a small, narrow muscle consisting of two portions, the outer and inner. The outer portion is superficial and originates from the flexor retinaculum of the wrist. The inner portion is deep and originates from the ulnar side of the metacarpal bone. These two portions join to form a tendon that inserts in the proximal phalanx of the thumb. This muscle is innervated by motor branches of the the median nerve and is supplied by branches of the radial artery. The flexor pollicis brevis flexes and rotates the thumb. The
flexor pollicis brevis muscle is a part of the thenar eminence.
Research Flexor Pollicis Brevis