Hand Surgery Source

Muscle Test: Hypothenars [Ulnar Intrinsics]

Test, Exam and Signs

Abductor digiti minimi (ADQ)
Origin:
  • Pisiform bone
  • Tendon of flexor carpi ulnaris
  • Pisohamate ligament
Insertion:
  • 5th digit (base of proximal phalynx, ulnar side)
  • Dorsal expansion of extensor digiti minimi
Innervation:

 
Cervical root(s):
  • C[7]8-T1
Nerve:
  • Ulnar (Deep [motor] branch)
Flexor Digiti Minimi Brevis (FDMB)
Origin:
  • Hamate (Hook)
  • Flexor retinaculum
Insertion:
  • Medial aspect of base of proximal phalynx of the 5th digit
Innervation:

 
Cervical root(s):
  • C[7]8-T1
Nerve:
  • Ulnar (Deep [motor] branch)
Opponens Digiti Minimi (ODQ)
Origin:
  • Hamate (Hook)
  • Flexor retinaculum
Insertion:
  • 5th metacarpal (whole length of ulnar margin and adjacent palmar surface)
Innervation:

 
Cervical root(s):
  • C[7]8-T1
Nerve:
  • Ulnar (Deep [motor] 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.

Abductor digiti minimi (ADQ)

Position of patient’s hand and upper extremity
  • Forearm is supinated, and the wrist is in neutral. Fingers start in extension sand adduction. MP joints in neutral and avoid hyperextension

Examiner’s actions
  • Support the wrist in neutral. The fingers of the other hand are used to give resistance on the distal phalanx, on the radial side of the finger and the ulnar side of the adjacent finger (ie. They are squeezed together).

Instructions for the patient
  • “Spread your fingers. Hold them. Don’t let me push them together.”

Flexor digiti minimi brevis (FDMB)

Position of patient’s hand and upper extremity
  • Short sitting or supine with forearm in supination. Wrist is maintained in neutral. The metacarpophalangeal (MP) joints should be fully extended; all interphalangeal (IP) joints are flexed.

Examiner’s actions
  • Stabilize the metacarpals proximal to the MP joint. Resistance is given on the palmar surface of the proximal row of phalanges in the direction of MP extension.

Instructions for the patient
  • “Uncurl your fingers flexing your knuckles. Hold it. Don’t let me straighten your knuckles.” The final position is a right angle at the MP joints.

Opponens Digiti Minimi (ODQ)

Position of patient’s hand and upper extremity
  • Forearm supinated, wrist in neutral, and thumb in adduction with MP and IP flexion.

Examiner’s actions
  • Stabilize the hand holding the wrist on the dorsal surface.  The examiner may prefer the hand to be stabilized on the table.

Instructions for the patient
  • “Bring you thumb to your little finger and touch the two pads, forming a letter `O’ with the thumb and little finger."
Presentation Photos and Related Diagrams
  • Hypothenar muscle loss secondary to chronic ulnar nerve lesion.
    Hypothenar muscle loss secondary to chronic ulnar nerve lesion.
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
  • When testing the OP, the flexor pollicis longus and the FPB can draw the thumb across the palm towards the little finger. If this motion occurs in the plane of the palm, it is not in opposition, and contact will be at the tips, not the pads of the digits. Also, the ABPB may substitute, but the rotation component of the motion will not be present.
Diagnoses Associated with Tests, Exams and Signs
Video
Hypothenar Muscle Testing
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.
  2. Kendall FP, McCreary EK, Provance PG. Muscles Testing and Function. 4th ed. Baltimore, MD: Williams & Wilkins, 1993, pp. 235–298.