Muscle Test and Tendon Exam: Flexor Pollicis Longus (FPL)

Exams and Signs

Origin:	Radius (anterior surface of middle 1/2) and adjacent interosseous membrane Ulna (coronoid process, lateral border [variable]) Humerus (medial epicondyle [variable])
Insertion:	Thumb (base of distal phalanx, palmar surface)
Innervation:	Cervical root(s): C7 and C8 Nerve: median nerve (anterior interosseous branch)

Grading of muscle strength:

Grade	Strength	Description
5*	Normal	Completes full range of motion against maximal finger resistance
4*	Good	Tolerates moderate resistance
3	Fair	Completes full range of motion with no resistance
2	Poor	Completes partial range of motion
1	Trace	Slight contractile activity
0	Zero	No contractile activity
*The distinction between Grades 4 and 5 is based on comparison with the normal hand and, barring that, extensive experience in testing the hand.

Position of patient's hand and upper extremity

Forearm is supinated, the wrist is in neutral and the metacarpophalangeal (MP) joint of thumb is in extension.

Examiner’s Actions

Stabilize the MP joint of the thumb firmly in extension by grasping the patient’s thumb across that joint. Apply resistance with the other hand against the palmar surface of the distal phalanx of the thumb in the direction of extension.

Instructions for the patient

Presentation Photos and Related Diagrams

FPL Muscle Testing.
FPL anatomy illustration
This illustration represents the anatomy of the muscle and tendon origin and insertion. Should an individual sustain a laceration as depicted, the observer can assume that the underlying tendon may be at risk for complete transection. A proper examination is needed to determine the integrity of the tendon.

Definition of Positive Result

In muscle testing, a normal result is a positive one. During a normal muscle test, the examiner should observe a normal muscle contraction that can move the joint or tendon against full resistance.

Definition of Negative Result

In muscle testing, an abnormal result is a negative one. During an abnormal muscle test, the examiner should observe an abnormal muscle contraction that can move the joint or tendon. In a complete denervation injury, such as a complete nerve laceration, there will be no evidence of any muscle function and the muscle testing grade will be 0.

Comments and Pearls

Do not allow the distal phalanx of the thumb to extend at the beginning of the test. If it is extended and then relaxes, the examiner may think that active flexion has occurred

Diagnoses Associated with Exams and Signs

References

Hislop JH, Avers D, Brown M. Daniels and Worthingham's Muscle Testing, Techniques of Manual Examination and Performance Testing. 9th ed. St. Louis, Missouri: Elsevier Saunders, 2014, pp. 138–202.
Kendall FP, McCreary EK, Provance PG. Muscles Testing and Function. 4th ed. Baltimore, MD: Williams & Wilkins, 1993, pp. 235–298.