Name
Pronunciation
(FLEK-sur POL-uh-sus LONG-gus)
Origin/Proximal Attachment
Middle anterior surface of radius
interosseous membrane (may also originate from lateral border of coronoid process or medial epicondyle)
Insertion/Distal Attachment
Palmar aspect of base of distal phalanx of thumb (deep to flexor retinaculum)
Action/Relevance
Flexes the distal phalanx of the thumb
Flexes the other joints to the wrist (Metacarpophalangeal, Carpometacarpal, & weakly at the wrist joints)
Innervation
Anterior interosseous branch of median nerve (C8, T1)
Notes
Flexor pollicis longus is one of the muscles of the forearm. It arises from the anterior surface of the radius distal to the anterior oblique line and the neighbouring interosseous membrane.
It passes distally deep to the flexor retinaculum in a separate flexor sheath to the majority of the flexor tendons. It inserts into the volar base of the distal phalanx of the thumb.
Flexor pollicis longus is innervated by the anterior interosseous branch of the median nerve (C7,C8).
It acts to:
* flex the interphalangeal joint of the thumb
* flex the more proximal metacarpophalangeal and carpometacarpal joints of the thumb
* weakly flex the wrist joint