Adductor Pollicis Muscle Exam

  • The Froment's sign can be used to evaluate the adductor pollicis muscle.
  • The adductor can also be tested by placing the thumb flat on the palm with the tip between the extended index and long fingers. Next the patient is asked to move the thumb towards the base of the little finger while the examiner applies an abduction force to the thumb's proximal phalanx. A normal adductor should have a normal 5 out of 5 muscle testing grade.
Diagrams & Photos
  • Adductor pollicis. Note the transverse and blue heads.
    Adductor pollicis. Note the transverse and blue heads.
  • Normal froment's sign ("O" sign). The thumb MP joint is not hyper-extended. the thumb IP joint is only moderately flexed, and the long finger is not supporting the index finger.
    Normal froment's sign ("O" sign). The thumb MP joint is not hyper-extended. the thumb IP joint is only moderately flexed, and the long finger is not supporting the index finger.
  • Positive Froment's sign. Note the first dorsal interosseous muscle atrophy, the marked thumb IP joint flexion, the long proximal phalanx supporting the index proximal phalanx, and the space between the thumb and the index is a rectangle not a circle ("O").
    Positive Froment's sign. Note the first dorsal interosseous muscle atrophy, the marked thumb IP joint flexion, the long proximal phalanx supporting the index proximal phalanx, and the space between the thumb and the index is a rectangle not a circle ("O").
Key Points
  • The adductor pollicis is innervated by motor branch of the ulnar nerve.
  • The positive Froment's sign is caused by the denervation of the adductor pollicis and the first dorsal interosseous muscles.
Grading of Muscle Strength
Exam References
Anatomic Abbreviations
Hand Surgery Resource Exams & Signs Library