Muscle Test and Tendon Exam: Palmaris Longus

Test, Exam and Sign Description

Muscle Testing: Palmaris Longus (PL)

Origin: Humerus (medial epicondyle via common flexor tendon)

Intermuscular septa and deep fascia

Insertion: Flexor retinaculum

Palmar aponeurosis

Slip sent frequently to the short thumb muscles

Innervation: Cervical root(s): C7–8

Nerve: median nerve

Grading of muscle strength:

Grade	Strength	Description
5*	Normal	Completes range of motion and holds against maximal finger resistance
4*	Good	Completes range against moderate resistance
3	Fair	Completes range of motion with no resistance
2	Poor	Completes range of motion
1	Trace	Palpable or visible contractile activity, which may or may not be accompanied by a flicker of motion
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

Sitting or supine with palm up. Stabilize the hand while it is cupped and in wrist flexion.

Examiner’s actions

Apply resistance against wrist flexion (in the direction of wrist extension); apply resistance toward opening the hand. Ask the patient to flex the wrist and then to touch the small finger to the thumb. Observe the PL tendon contract.

Instructions for the patient

“Flex your wrist. Touch your thumb to your little finger.”

Presentation Photos and Related Diagrams

Palmaris Longus Muscle Testing
PL 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 zero.

Comments and Pearls

The palmaris longus (PL) is absent in many individuals (about 20%).
The palmaris longus (PL) an excellent tendon graft source.
The palmaris longus (PL) is only 1-2mm superficial to the median nerve at the wrist. If this tendon is lacerated one should carefully exclude an associated median nerve injury.

Diagnoses Associated with Tests, Exams and Signs

RHEUMATOID ARTHRITIS

EXTENSOR TENDON RUPTURE (VAUGHAN-JACKSON SYNDROME)

Video

Muscle Testing Palmaris Longus (PL)

References

1. 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.