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Flexor Pollicis Longus Anatomy: Origin, Insertion, Action

Flexor Pollicis Longus Origin, Insertion, Action, Innervation

Flexor Pollicis Longus

O, I, A of the Flexor Pollicis Longus

Origin: Middle anterior surface of the radius and the interosseous membrane. The muscle may also originate from the lateral border of the coronoid process of the ulna or the medial epicondyle of the humerus.
Insertion: Palmar aspect of the base of the distal phalanx of thumb
Actions: Flexion of the thumb
Innervation: Anterior interosseous branch of the median nerve (C8, T1).
Vascular Supply: Muscular branches from the radial artery and the anterior interosseous artery from the ulnar artery.

Primary Actions of the Flexor Pollicis Longus:

1. Flexion of the thumb at the interphalangeal joint

  Agonists: None

  Antagonists: Extensor Flexor Pollicis Longus

2. Flexion of the thumb at the carpometacarpal joint

  Agonists: Flexor Pollicis Brevis, Adductor Pollicis, Opponens Pollicis

  Antagonists: Extensor Pollicis Brevis, Abductor Pollicis Longus

Secondary Actions of the Flexor Pollicis Longus:

1. Assists with flexion of the thumb at the metacarpophalangeal joint

  Agonists: Flexor Pollicis Brevis

  Antagonists: Extensor Pollicis Brevis, Extensor Pollicis Longus, Abductor Pollicis Longus

2. Assists with flexion of wrist

  Agonists: Flexor Carpi Radialis Longus, Palmaris Longus, Flexor Carpi Ulnaris

  Antagonists: Extensor Carpi Radialis Longus, Extensor Carpi Radialis Brevis, Extensor Carpi Ulnaris

Note: Flexor digitorum superficialis and flexor digitorum profundus also assist with flexion of the wrist.



Information about cause and effect of Flexor Pollicis Longus pain:

Flexor Pollicis Longus Muscle: Thumb Pain

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