Palmaris Longus Anatomy

Flexor Pollicis Longus Muscle

Origin:  Medial epicondyle of the humerus via the common flexor tendon
Insertion:  Central portion of the flexor retinaculum and superficial portion of the palmar aponeurosis
Actions: Assists with flexion of the wrist
Innervation: Median nerve (C7, C8)
Blood Supply: Muscular branches from the ulnar artery

Primary Actions of the Flexor Pollicis Longus

1.  Flexion of the thumb at the interphalangeal joint

  Agonists:

  • None

  Antagonists:

  • Extensor 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

 

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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

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