Clinical
Assessment
Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Wim Brandsma, PT, PhD; Ton A.R. Schreuders, PT, PhD, CHT-NL
Key Recommendations for Outcome Evaluation
1.
International Classification of Functioning Category: b7300 (power of isolated muscles and muscle groups).
2.Measures:
• MMT using the 6-level Medical Research Council (MRC) grading should be used to assess
neuromuscular functioning when a nerve lesion is suspected or known.
• MMT will not be considered a valid measure to evaluate progression of muscular strength once grade 4
has been achieved.
• Quantitative measures, such as hand-held dynamometry, can be used to measure the progression of
intrinsic and extrinsic strength using the same principles of positioning/resistance to isolate muscles.
The evidence on tests, methods, and tools is emerging but insufficient to suggest a single device or
approach. Comparability of results across methods should be done with caution.
3.Procedures: The examiner will use positioning and resistance to isolate the primary mover innervated
by the nerve of interest (as outlined in this chapter and text/papers that have been validated through
electrodiagnostic and other basic studies). The use of specific and consistent handling, positioning, point of
application of resistance, verbal instruction, documentation of any potential factors limiting the validity of
the measure, and format for documentation are essential to comparability across occasions and examiners.
4.Interpretation: The MRC grades will be used. Documentation of potential factors that might confound
results should be performed (e.g., pain, abnormal muscle tone, limited joint range of motion, confusion,
abnormal sensation, or lack of cooperation to produce a maximum performance).
American Society of Hand TherapistsTM • www.asht.org
1
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Overview of Testing
Conceptual Basis for Testing
Manual muscle strength testing (MMST) is the process of
assessing muscle strength and answers the question defined
by the Medical Research Council (MRC): Can a muscle or
muscle group move a joint segment through its full range of
motion, with or without gravity eliminated, or is there only a
palpable contraction?1 (Table 1)
MEDICAL RESEARCH
COUNCIL (MRC) SCALE
6 grades
5 Full range of motion;
full resistance
4 Full range of motion;
some resistance
MODIFICATIONS
9 grades
4+ Moderate resistance
3+ Minimal resistance
2+ Nearly full range
3 Full range of motion;
no resistance
2 Decreased range of motion
1 Muscle flicker
0 Complete paralysis
Table 1. Medical Research Council Grading System
The MRC scale originally grades 4-5 against gravity and 0-3
with gravity eliminated. For muscle grading of small muscles,
the effect of gravity is negligible and need not be taken into
account, save maybe the wrist.7
The main purpose of muscle testing is to determine the
continuity and integrity of the motor unit and strength of
specific muscles. Therefore, MMST of the hand and wrist
enables the examiner to assess impairments in strength,
which may yield valuable information regarding nerve/muscle
function and neuromuscular disease processes. These findings
can then be used as baseline data against which changes in
neuromuscular function can be evaluated and their effects on
hand function researched.
Apart from the main purpose as stated earlier, muscle
(strength) testing also has a place in detecting if there is
discontinuity in the muscle-tendon unit or whether there are
adhesions of a tendon that may prevent or limit the muscle
American Society of Hand TherapistsTM • www.asht.org
from transmitting its force, although there is little empirical
evidence on this role. These “secondary” indications will
not be further discussed in this document; the focus of this
document will be on MMST in relation to assessment of
motor nerve function.
Muscle Weakness/Paralysis and Hand
Function in the Context of the International
Classification of Functioning
The International Classification of Functioning (ICF) was
developed to create uniformity in language to describe
and evaluate health conditions. Grading individual muscle
strength can be conducted using the MRC scale (0-5) or by
using hand-held dynamometers. Both types of testing/grading
fall under ICF category b7300 (power of isolated muscles and
muscle groups).
The consequences of muscle weakness or paralysis of the
hand can be reflected at the activity level in fine hand use
(d440), hand and arm use (d445), and carrying, moving, and
handling objects (d449). Hence, muscle strength testing and
grading, both manual and with dynamometers, can be useful
to establish relationships between strength and function with
the use of validated questionnaires and hand activity tests.
Tests and Subtypes/Variations of
Measurement
All manual muscle strength tests for the intrinsic and extrinsic
muscles of the hand and wrist will be described in detail.
Multiple grading systems have been described for MMST.
Grip and pinch strength measurements with grip/pinch
dynamometers are presented elsewhere in the manual but
some issues are also discussed in this chapter.
Understanding MMST
The first publications about MMST appeared about 100
years ago when poliomyelitis was very prevalent.2 A practical
clinical system was needed to assess the extent of paralysis
and to monitor possible recovery. In 1936, Florence Kendall
developed a percentage grading system that first introduced
the factor of fatigue in grading.3 The classic document
developed after World War 2 was the Aids to the Investigation
of Peripheral Nerve Injuries.1 This manual illustrates the
major actions of limb muscles and how they should be
tested; defines the concepts of prime movers, synergists, and
antagonists; and includes the muscle grading scale familiar
2
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
to all therapists and doctors. A modified (fourth) version of
this manual, Aids to the Examination of the Peripheral Nervous
System, was published in 2000.4
Because the MRC system was intended to be used to grade
recovery from total paralysis (grade 0), the greatest emphasis is
placed on severe degrees of weakness (grades 1, 2, and 3). The
grading system is ordinal, with differences between the grades
not assumed to be equal.5 Hence, it was designed to measure
motor nerve functionality. Other grading systems have been
developed. Several important ones will be described in this
chapter.
For a further review of the history of MMST and other
relevant aspects, the reader is referred to other articles.3,6-12
Construct Being Measured
MMST assesses the ability of the neuromuscular unit to exert
force using active muscular contraction if not limited by other
factors, e.g., joint mobility, muscle excursion (shortening or
adhesions), pain, and coordination. It requires the synergy of
several muscles of the upper extremity because few muscles
can be tested in isolation, needing synergistic contractions
of other muscles to stabilize joints to make a required
movement/test possible.
Applying MMST
MMST is mainly used in the orthopedic, neurological,
medical, chiropractic, and physical therapy areas to assess
muscle strength and to determine a patient’s progress or
deterioration over time.
The main purpose of MMST in hand therapy is to evaluate
and monitor the function of the motor neuron in peripheral
nerve pathology, e.g., peripheral or nerve root lesions,
entrapments and infections, and (poly)neuropathies such
as hereditary motor and sensory neuropathy (HMSN) or
Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis
(ALS, Lou Gehrig’s disease), and Guillain-Barré syndrome,
among others. Additionally, MMST may be used in:
• establishing muscle/tendon (dis)continuity
• determining full excursion of muscle/tendon unit, e.g.,
are there adhesions along its pathway?
• determination of suitable donors in connection with
tendon transfer surgery (these issues will not be part of
this chapter)
American Society of Hand TherapistsTM • www.asht.org
A relative contraindication for MMST is the presence of pain.
Naturally, in all other acute and chronic joint conditions
(e.g., fractures, sprains, and inflammation), MMST is not
indicated. MMST is also not indicated in the first few weeks
following tendon repair, tendon transfers, or other surgical
procedures in which healing structures must be protected.
Further, MMST was not designed to measure progression in
strength once full innervation and anti-gravity strength has
been obtained because grades 4 and 5 will cover a wide range
of muscle capability.
In the following sections, MMST will mainly be discussed in
the context of peripheral nerve pathology, neuropathy, and
nerve lesions.
Conceptual/Theoretical Basis
for the Construct
The function of a muscle can be divided into three aspects:
force or strength (N), endurance (time in seconds), and
velocity (m/sec). However, in most muscle strength tests,
only the first aspect, strength, is tested, which sometimes is
referred to as the maximum voluntary contraction (MVC).
In strength measurements, the MVC is generally determined
by asking the patient to squeeze or push “as hard as you can.”
In case of full ROM in MMST, the therapist will then (try
to) break the resistance. In activities of daily living (ADL),
these maximum muscle contractions are rarely used, except
for some specific activities, e.g., when lifting a heavy suitcase
or opening a tight jar. Usually, a much lower level of strength
is sufficient to perform most of our ADL, especially in whitecollar workers. The second aspect, endurance or rather lack of
it (fatigue), is probably particularly relevant in patients with
impaired muscle function due to, e.g., multiple scleroses, ALS
or HMSN.13
According to Cuthbert and Goodheart, to achieve accurate
results, muscle tests must be performed according to a
protocol.14 They state that the following factors must be
carefully considered when testing muscles in clinical and
research settings:
• proper positioning so the test muscle is the prime mover
as much as possible
• adequate stabilization of other joints
• observation of the manner in which the patient or
subject assumes and maintains the test position, trying,
unwittingly, to compensate/substitute for weakness/
paralysis
3
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
•
•
•
observation of the manner in which the patient or
subject performs the test
consistent timing, pressure, and position
non-painful contacts (non-painful execution of the test)
Muscle Grading
The MRC grading system is universally accepted. All
published reliability studies on MMST use this system. The
grades are defined by three variables: ROM, resistance, and
gravity (Table 1).
In both early and current publications, gravity is also
mentioned as a factor that may influence the muscle
performance. In the experience of the authors of this chapter,
the effect of gravity is not important when testing the muscles
of the fingers and possibly also the wrist.8
Smith et al. developed a numerical index for clinical research
in muscle testing, adding a plus (+) and minus (–) to the
standard grades.15 Paternostro et al. suggested a 9-point
scale,16 Florence et al. have used an 11-point scale in the
assessment of children with Duchenne dystrophy,17 and
Bohannon and Walsh defined a 13-point scale.12 Such detail
is not always possible or practical for the muscles of the hand.
For the hand, a 9- or 6-point scale may suffice when manually
evaluating the strength of the muscles of the hand.7,8,18
Figure 1. Comparison of the MRC scale (upper line) with force in
newtons (N) of the dynamometer (bottom line) in elbow flexor
measurements.21
Factors That May Compromise Test Results
Five important factors may influence the validity of MMST:
1. Pain: The presence of pain may inhibit MVC.
2. Lack of sensation might cause higher than expected
values because the absence of pain will help the hand to
deliver power beyond physiological limits.
3. Joint contractures may limit maximum ROM. Muscle
grading according to MRC scale is defined by ROM
(grade 3 and above). Note that normal strengthresistance can be present with reduced range.
4. Lack of control due to spasticity.
5. Cognitive: A lack of ability to understand the procedure
may produce involuntary lack of adherence to test
demands.
6. Motivational: A subject may be voluntarily nonadherent to test demands, purposely showing weakness/
paralysis.
In many conditions seen by the hand therapist in which
MMST is indicated, the problem is unilateral, allowing
the contralateral hand to be the normative reference hand.
Testing the unaffected hand for comparison may be especially
important in the subnormal, or weak, range (grades 5– and
4+), when the therapist really wants to be certain that there
is definite motor function impairment. The authors feel that
hand dominance is not a factor of importance in MMST.
Studies by MacAvoy and Green19 and van der Ploeg et al20
(Figure 1) show that, with less than 10% of MVC, you can
move a joint though its full ROM. This study was about the
elbow but the same finding may apply to MMST for muscles
of the hand and wrist, i.e., that minimal MVC is needed
for grade 3, leaving disproportional large “room” for grade
4. Grade 4 is clinically the most relevant grade: Is motor
function impairment present?
American Society of Hand TherapistsTM • www.asht.org
4
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Assessment: Evaluation Form for MMST of the Wrist and Hand
American Society of Hand TherapistsTM • www.asht.org
5
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Reliability
The skills of the examiners conducting studies on MMST and
their skills in interpreting the derived information will affect
the usefulness of MMST data.14 Reliability studies have been
published that focus on the intrinsic muscles of the hand
(Table 2).7, 18
Brandsma, 1995
28 hands:
6-point scale
Intratester
reliability
Inter-tester
Inter-tester
Abd. Digit 5
0,96
0,79
0,89
Add. Digit 2
0,72
0,72
not
assessed
Abd. Index
0,8
0,74
0,96
0.79-1
0,96
0,8
0,78
0.62-0.94
Opp.
Thumb
0,9
0,81
0,87
0.69-1
Index
0,8
0,78
0,9
0.72-1
Middle
0,85
0,77
0,94
0.76-1
Ring
0,71
0,75
0,93
0.75-1
Little
0,83
0,93
0,92
0.74-1
Abd. Thumb
Intrinsic
Position
Brandsma, 1998
144 hands:
9-point scale
95% CI
0.71-1
Table 2. Brandsma, 1998: Three testers involved.
Results shown are for AB pair. BC and AC results are very similar.
In the first study, the inter- and intratester reliability
coefficients were presented for 10 intrinsic muscle tests.
The study reported good reliability with better reliability
coefficients when the test was repeated by the same tester. This
is a common finding in observer/tester reliability studies.
The second study reported the intertester reliability from a
larger patient population (n = 72) with 3 experienced testers
for 9 of the 10 tests in the first study (adduction of the little
finger was omitted). In this study, the MRC 6-point grading
scale was refined to a 9-point scale. The calculated reliability
coefficients (Kw: weighted kappas) were all good (Altman,
1991) but direct agreement was very poor. It was therefore
recommended that, in the hospital where the study was
conducted, only the whole numbers/grades are “valued” until
acceptable direct intertester agreement can be shown on an
expanded (9-point) scale. In this case, clinical decisions in the
management of neuritis, changing dose of corticosteroids, are
based on reported nerve assessment outcomes and therefore
need to have a high degree of reliability.
American Society of Hand TherapistsTM • www.asht.org
Roberts et al found that reliability (Kw) for muscles
predominantly supplied by ulnar nerve ranged from 0.71
upward, indicating good to very good agreement.22 For these
tests, the percentage of agreement to within 1 grade ranged
from 89% upward. For the median nerve-supplied muscles, 5
testers achieved Kw values of 0.87 or higher, and all 9 testers
graded at least 97% of assessments within 1 grade of the
gold standard, a senior therapist with more than 15 years of
experience in daily muscle testing.
A systematic review on manual muscle testing or manual
muscle test showed good reliability and validity in the use of
MMST for patients with neuromusculoskeletal dysfunction.14
Twelve randomized controlled trials were reviewed that were
used by chiropractors, physical therapists, and neurologists.
In this review on muscle testing mainly in larger muscle
groups like hip, shoulder, and back muscles, it was concluded
that the levels of agreement, based upon a margin of one
grade, were high, ranging from 82% to 97% agreement for
interexaminer reliability and from 96% to 98% for test-retest
reliability. The results of these studies indicate that, in order
to be confident that a true change in strength has occurred,
MMST scores must change more than one full grade. In
the 11 studies, the coefficients ranged from 0.63 to 0.98 for
individual muscle groups, and from 0.57 to 1.0 for a total
MMST score (comprised of the sum of individual muscle
grades).
Florence et al reported acceptable reliability on an 11-point
scale but only weighted kappas were reported.17 Proximal
muscle groups showed higher reliability than distal groups.
The reliability coefficients for the two tests of two hand
movements in this study, wrist extension and thumb
abduction, were 0.69 and 0.71, respectively. However, in this
study, only one movement relevant to hand therapists was
tested.
Validity
Buschbacher determined in a prospective study (n = 217) the
sensitivity and specificity of MMST in detecting weakness
of the ulnar and median innervated muscles and compared
the results with “confrontational strength testing.”23 In
confrontational testing, a muscle (group) is tested against its
contralateral counterpart, e.g., abducting the little fingers
against each other. He found a significantly higher sensitivity
6
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
for confrontational testing as compared to MMST: 82%
and 14%, respectively, for abduction of the little finger. For
abduction of the thumb, the difference was much less: 16%
and 6%, respectively. Specificity was 100% in all tests. In
this test, however, the outcome is nominal, positive-negative,
whereas in MMST testing, the grading is ordinal.
In some carpal tunnel syndrome studies, the sensitivity of
thumb abduction was also poor.24-29 The poor sensitivity of
thumb abduction MMST results is to be expected due to
the fact that motor function impairment is typically a late
occurrence in carpal tunnel syndrome. Also see Lamb’s work
on the issue of validity.10
van Brakel et al concluded that, in a prospective study
in which electroneurophysiological tests such as nerve
conduction and warmth perception threshold testing were
used, “… changes in muscle testing scores (and monofilament
testing), confirm their validity as screening tools.”31
Modest correlations were found between MMST and
dynamometry (Rotterdam Intrinsic Hand Myometer
[RIHM], see “Intrinsic Hand-Held Dynamometer” in this
chapter) of the intrinsic hand muscles, ranging between 0.65
and 0.80.32 There was a significant relation found between
MMST and the RIHM dynamometry measurements of all
4 movements; Spearman correlation coefficients were 0.65,
0.63, 0.85, and 0.56 for little finger, index, and thumb
abduction and opposition of thumb, respectively (p-values
from 0.001 to 0.014).33
MMST is often used to diagnose nerve lesions. In this
context, it should be noticed that many pathognomic signs
are known in connection with an ulnar lesion.34,35 The value
of these signs is very limited as it is “grading” at a nominal
level; present, not present, with unknown sensitivity and
specificity.
Muscles vs Movements
It has been emphasized that prime movers and synergists
are often tested together, not individual muscles. However,
it should be pointed out that every muscle is a prime mover
in some specific action. MMSTs are designed to replicate
the primary vector of motion of a muscle while minimizing
the contribution of secondary mover muscles. During an
American Society of Hand TherapistsTM • www.asht.org
“isolated” muscle test (individual MMST), the designated
primary mover muscle should have the highest level of
activity, compared with the secondary mover or synergist
muscles, with minimal contribution of secondary muscles.36
Most of the intrinsic and many of the extrinsic muscles
cannot be tested “in isolation.” This has been confirmed by
electromyography studies.37,38 Brunnstrom and Dennen
(1941), based on their experience with polio patients before
World War II, stated that, in many instances, movements
were graded rather than individual muscles. For example, in
testing the motor function of the ulnar nerve, the therapist
would test abduction of the little finger rather than the
abductor digiti minimi muscle.8
Muscle testing evaluates the strength of response of the muscle,
not the speed of response. Muscle testing is an art in which
the force applied to the patient is increased at a constant rate
until the tester senses the muscle begin to give way. The classic
“break test” used by physical therapists tests this phenomenon
as well.
Clinical changes are expressed in grade changes that either
result from change in ROM 1-2 > 3, or increase in force that
can be overcome 3 > 5, i.e., mild (3+), moderate (4–, 4+),
strong (5).
A new system of grading for MMST should retain the
advantages of the MRC: wide acceptability, ease of use,
usefulness for most muscles, and applicability to motor
recovery from all types of nerve injury (e.g., deterioration
based on progressive neuromuscular disorders).
Useful potential modifications of the MRC include a grade
for a muscle that achieves strength against resistance but not
against gravity and a standardized subdivision of grade 4: mild
(4–), moderate (4), good (4+), and normal/strong (5).
Intrinsic Hand-Held Dynamometer
Instruments such as the RIHM are now available to perform
quantitative measurements of the intrinsic muscles of the
hand.39
The RIHM was designed such that it can measure a wide
range of muscle groups, such as the abduction and adduction
strength of the little finger and index finger and the
opposition, palmar abduction (anteposition), and opposition
strength of the thumb and intrinsic muscles of the fingers
7
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
combined in the intrinsic plus position. See: http://www.
handweb.nl/index.php?pid=133.
Reliability of RIHM measurements in nerve injury patients
was comparable to grip and pinch strength measurements and
is appropriate to study the functional recovery of the intrinsic
muscles of the hand in isolation. In clinical evaluation
and research studies on patients with hand problems,
muscle strength is often based on grip and pinch strength
dynamometry. It has been shown that changes in grip-pinch
strength are not necessarily related to changes in intrinsic
muscle strength because of the dominant contribution of the
extrinsic hand muscles to these measurements.40,41
In a study comparing the strength of the hand muscles in
46 patients with neuropathies like HMSN, in which the
correlations between the different strength measurements
of intrinsic and extrinsic muscles and hand function
measured with the modified Sollerman test and the DASH
questionnaire,32 it was found that intrinsic muscle strength
was positively correlated with the Sollerman test, which
specifically measures fine motor tasks. In contrast, extrinsic
muscle strength was more strongly correlated with the DASH,
which is a more global measure of upper extremity function.
In a review on CTS outcome measures, Geere et al concluded
that, in theory, MMST should be more specific when testing
the thenar musculature, whereas dynamometry may be more
sensitive if assessed using a hand-held dynamometer like the
RIHM.42
Tests for
Intrinsic Muscles
full extension. The patient is then asked to abduct the little
fingers against one another. Abduction of the little finger in
the affected hand will be weak or not possible. The same can
be done with the thumbs to test for integrity of the median
nerve.
In case of nerve laceration and repair, more movements/
muscles should be tested and graded. In cases of suspected
nerve entrapment, detailed testing is needed to determine at
which site the nerve may be compressed.
Prior to the actual muscle testing, the examiner has
demonstrated the required movement and has verified
that full ROM is available and that pain is not a possible
inhibiting factor.
Abduction of the Little Finger
Primary muscle: abductor digiti minimi, but all hypothenar
muscles are active; flexor digiti minimi, opponens digiti
minimi.
The therapist supports the patient’s hand, palm up,
holding the middle, ring, and index fingers. The little
finger is passively fully abducted while keeping the
metacarpophalangeal (MCP) joint in slight flexion to observe
the full ROM, and the patient is asked to hold the finger in
that abducted position (Figure 2). If the little fingers maintain
this position, they must exert a force equivalent to grade 3. If
the patient is able to hold the fingers into abduction, manual
resistance is applied at the ulnar side of the proximal phalanx
of the little finger in a direction toward the ring finger. If the
patient is not able to maintain the abducted position, then
the contraction of the hypothenar is assessed to determine the
grade 0, 1, 2, or 3.
Testing the intrinsic muscles serves to assess and monitor
the motor function of peripheral nerves and cervical nerve
root function. It is assumed that, in neuropathies, most of
the muscles in the same nerve distribution will be weak/
paralyzed to the same degree and extent. In such instances, it
is therefore not necessary to test each and every muscle that is
innervated by the nerve whose function is compromised.8
Some suggestions for quick testing are Froment sign and
“confrontational testing” for ulnar palsy.23 In the latter test,
the patient is asked to put the adducted little fingers against
each other on their ulnar borders while holding the fingers in
American Society of Hand TherapistsTM • www.asht.org
Figure 2. Abduction of the little finger.
8
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Abduction of the Index Finger
Primary muscle: first dorsal interosseous.
With the forearm of the examinee in neutral position, the
therapist asks the patient to abduct the index finger while
keeping the MCP joint flexed. The thumb of the supporting
hand of the therapist is resting in the first web space to feel
for possible muscle contraction in case of severe weakness. If
there is full ROM, manual resistance is given on the radial
aspect of the base of the proximal phalanx of the index finger
in an ulnar direction (Figure 3).
interosseous muscle will often be innervated from the median
nerve through the ulnar nerve at the mid-forearm level.43
Local pathology at the level of the wrist, in Guyon’s canal or
distal to it where the ulnar nerve branches, may also result in
weakness or paralysis of the ulnar innervated muscles, which
is different from the muscle loss seen in ulnar involvement
proximal to the wrist.7
Intrinsic-Plus Position
Primary muscles: interosseous and lumbrical muscles.
The patient is asked to place the fingers in the so-called
“intrinsic-plus”: flexion of the MCP joints and extension of
the interphalangeal (IP) joints. If the patient is able to move
to this position, active resistance is applied on the volar side
of the proximal phalanx toward extension (Figure 4). The
suggested grading for this movement is for grades 3, 4, and
5 as per MRC scale. Grade 2: When asking for the intrinsic
position, the finger is less than 30 degrees short of full
extension at the proximal IP (PIP) joint. Grade 1 does not
apply.
Figure 3a. Abduction of the index finger.
Figure 4. Combined Interosseous and Lumbrical.
Figure 3b. Abduction of the index finger.
There may be considerable or full strength of the first dorsal
interosseous muscle accompanied by paralyzed hypothenar
muscles (abduction of the little finger) in a high ulnar nerve
lesion. In those cases, a Martin-Gruber anastomosis should be
suspected. With a Martin-Gruber anastomosis, the first dorsal
American Society of Hand TherapistsTM • www.asht.org
This test gives additional information about ulnar innervated
muscles, specifically the interosseous muscles. Contrary to
what most textbooks on anatomy and MMST state, this
intrinsic-plus test is a function of the interosseous muscles.8
Unlike the interosseous muscles, there are no clinical tests in
which the activity of the lumbrical muscles can be graded on
an ordinal scale.
9
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
The terms lumbrical-splint and lumbrical-replacement could
be considered misnomers. The interossei are the primary
active muscles for MCP flexion in the so-called lumbrical
position. In tendon transfer procedures described as
lumbrical-replacement procedures transfers, it is the function
of the interossei that is replaced.
Two major clinical findings support this view: In low median
palsy, there is no weakness in the lumbrical test of the index
and middle fingers. Second, in ulnar palsy, there is usually
always weakness or overt clawing of the index and long
fingers.8,44
Thumb Adduction
Figure 5a. Thumb Palmar Abduction.
Primary muscle: adductor pollicis; secondary muscles:
extensor pollicis longus (EPL) and flexor pollicis longus
(FPL).
The adductor pollicis muscle is the most powerful intrinsic
hand muscle. Adduction of the thumb is obtained by several
muscles, including the extrinsic EPL and FPL muscles. The
muscles cannot be tested in isolation; the EPL and FPL
are also strong adductors of the thumb. Thumb adduction
strength is best evaluated with a pinch dynamometer in the
key pinch. Grading of individual palmar and dorsal interossei
(except first dorsal interosseous) is not needed for most
common conditions, and would also be difficult to grade with
MRC grades and would be superfluous with the tests already
given.
Thumb Palmar Abduction
Primary muscle: abductor pollicis brevis (APB); secondary
muscles: the opponens pollicis (OP), flexor pollicis brevis
(FPB), and abductor pollicis longus (APL).
With the forearm in supination and the hand in slight
extension at the wrist, the patient is asked to lift the thumb
away from the palm so the thumb is at a right angle to the
plane of the palm. When this full movement is possible,
resistance is given proximally on the radial aspect of the
thumb, MCP level, in a direction toward the palm. Resistance
is applied perpendicular to the plane of the palm of the hand
(Figure 5). Wrist extension eliminates contribution of the
APL toward thumb abduction.45
American Society of Hand TherapistsTM • www.asht.org
Figure 5b. Abductor Pollicis Longus.
Thumb Opposition
Primary muscles: OP-APB and FPB.
For testing thumb opposition, the person is asked to put the
hand in the same position as the test for thumb abduction.
Resistance is provided on the palmar surface of the patient’s
thumb over the head of the first metacarpal, parallel to the
plane of the palm of the hand. The finger providing resistance
rotates 90 degrees from the abduction test (Figure 6). The
patient is not allowed to flex the IP joint of the thumb.
10
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Figure 6a. Thumb Opposition.
Figure 7. MCP Flexion of Thumb.
Testing FPB strength is (too) difficult as: 1) It requires
coordination flexing the MCP joint while maintaining
extension at the IP joint. 2) It requires sufficient range of
motion of the MCP joint, which is not always present. Again,
for assessment and evaluation of most clinical conditions, the
MMST test for MCP flexion would be redundant. 3) The
muscle may be innervated by ulnar, median, or both.
Figure 6b. Thumb Opposition.
Thumb MCP Flexion Muscles
Primary muscle: FPB.
MCP flexion of the thumb can be graded, provided there is a
good range of joint motion. In this movement, the adductor
pollicis and abductor pollicis contribute to flexion along with
the FPB. The patient is asked to flex the thumb MCP joint
while keeping the IP joint extended (Figure 7). Resistance is
given at the base of the proximal phalanx toward extension.
Tests for
Extrinsic Muscles
As stated earlier, MMST of the intrinsic and extrinsic
muscles often is performed to assess and monitor the motor
function of the ulnar, median, and radial nerves in (mono)
neuropathies, nerve lacerations and repairs, and nerve root
lesions of the cervical spine. The testing of the extrinsic
muscles is also often performed to check for continuity or
discontinuity of the tendon or adhesions that prevent full
tendon excursion.
Wrist Extension: Extensor Carpi Radialis
Longus (ECRL) and Extensor Carpi Radialis
Brevis (ECRB)
With the forearm in pronation and supported by the
examiner, and the elbow flexed to 90 degrees, the person
is asked to extend the wrist with the fingers in a fist. This
decreases possible contribution of finger extensors to wrist
extension. Resistance is given on the dorsum of the hand in a
palmar-ulnar direction (Figure 8).
American Society of Hand TherapistsTM • www.asht.org
11
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Figure 8a. Extensor Carpi Radialis Longus.
Figure 9. ECU Wrist Extension.
Finger Extension: Extensor Digitorum
Communis (EDC)
The EDC muscle is tested by asking the person to
hyperextend the MCP joints while flexing the IP joints. The
wrist is kept in extension by the examiner (Figure 10). All
fingers may be tested simultaneously.
Figure 8b. ECRL and ECRB.
The ECRL and ECRB tendons insert at the bases of the
second and third metacarpals, respectively, and can be
palpated there. In a slender hand, the individual tendons may
be visible. A palpable and visible groove may be seen between
the two muscle bellies in the upper forearm. Differentiation
between the two muscle contractions may be possible by
changing the elbow position: first testing with the elbow
flexed and then with the elbow extended.46 The differentiation
between the two muscles is especially important in tetraplegia
when the transfer of one of these tendons may be considered
to enhance hand function.
Wrist Extensions: Extensor Carpi Ulnaris (ECU)
The ECU is tested by asking the patient to extend the wrist,
with forearm pronated and supported by the therapist.
Resistance is given on the dorso-ulnar side of the hand in a
volar-radial direction (Figure 9). The tendon can be palpated
distal to the ulnar styloid process.
American Society of Hand TherapistsTM • www.asht.org
Figure 10. EDC Flexion.
Finger Extension: Extensor Indicis Proprius
(EIP) and Extensor Digiti Minimi (EDM)
To test and grade the EIP and EDM, the subject is asked to
only extend the index and little fingers from the closed hand
position. Resistance is given on the dorsal side of the proximal
phalanx in a direction toward flexion. If the connection
between the EDC of the index and the middle finger is loose
enough, isolated extension of the index finger is possible
without the EIP.47
12
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Wrist Flexion: Flexor Carpi Ulnaris (FCU)
To test the FCU muscle, the patient positions the forearm
in supination and the therapist asks the patient to flex and
ulnar deviate the wrist. Resistance is applied toward radial
extension. The FCU tendon can easily be palpated (Figure
11a, 11b). With normal integrity of the ulnar-innervated
muscles, the FCU tendon is also palpable with little finger
abduction as the pisiform bone migrates. Both the FCU and
the hypothenar muscles insert into the pisiform. Contraction
of the FCU stabilizes the pisiform, allowing more efficient
contraction of the hypothenar muscles. Strength grading of
the FCU may be difficult as other muscles contribute to wrist
flexion.
may only be able to see and palpate the FCR. When present,
the PL tendon can be clearly visualized in the center of
the wrist, especially when the therapist asks the patient to
simultaneously oppose the thumb tip to the little finger tip
(Figure 12). This motion may or may not be possible given
the possible underlying pathology.
Figure 12. Palmaris Longus with Wrist Flexion.
Wrist Flexion: Flexor Carpi Radialis (FCR)
Figure 11a. Flexor Carpi Ulnaris.
Figure 11b. Flexor Carpi Ulnaris.
During wrist flexion, the FCR tendon is also easily palpated
near the center of the wrist just radial to the PL. To test the
FCR muscle, the patient positions the forearm in supination
and the therapist asks the patient to flex the wrist. Resistance
is applied toward extension (Figure 13).
Figure 13. Flexor Carpi Radialis.
Wrist Flexion: Palmaris Longus (PL)
The patient positions the forearm in supination and the
therapist asks the patient to flex the wrist without deviation.
Because many individuals do not have a PL tendon, one
American Society of Hand TherapistsTM • www.asht.org
13
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Finger and Thumb Flexion: Flexor Digitorum
Profundus (FDP)
The FDP is responsible for distal IP (DIP) joint flexion. The
muscle has a dual innervation: The ring and little fingers
are usually innervated by the ulnar nerve, and the index
and long fingers by the median nerve. The individual finger
flexor muscles are difficult to test in isolation, as the FDPs
have strong connections at the wrist level.48 In testing the
individual fingers, the therapist holds all finger IP joints
extended, allowing only the DIP joint of the finger to be
tested free. Resistance is applied toward extension (Figure
14). In the group test, the therapist asks the patient to flex
all fingers and then provides resistance on the palmar surface
of the fingertips to the flexed DIP joints in the direction of
extension. This test can be used to determine high and low
median nerve pathology. If the FDP of the little finger is weak
in high ulnar nerve pathology, the FDP of the index is weak
in high median nerve pathology. The test may be useful to
determine possible lesions of individual FDP tendons.
Figure 15. Finger flexion.
Finger and Thumb Flexion: FPL
The FPL muscle is the only muscle that flexes the IP joint
of the thumb. Therefore, testing IP flexion of the thumb is
the ideal test of the integrity of the median nerve if a lesion
proximal to the wrist is suspected. The therapist grasps the
patient’s thumb, stabilizes the carpometacarpal joint in neutral
and the MCP joint in extension, and asks the patient to flex
the thumb IP joint. Resistance is applied toward extension
(Figure 16).
Figure 14. Flexor Digitorum Profundus.
Finger and Thumb Flexion: Flexor Digitorum
Superficialis (FDS)
Individual FDS muscles are tested with all other fingers held
in extension by the examiner. The examiner asks for flexion
of the PIP joint, and resistance is applied toward extension
(Figure 15). Many people have a normally weak FDS to
the little finger and, in some cases, this muscle may even be
absent. In such cases, isolated PIP flexion will not be possible.
Also, in some patients, the ring finger must be allowed to
move with the little finger in order to see adequate movement
of the FDS in the little finger.49
American Society of Hand TherapistsTM • www.asht.org
Figure 16. Thumb flexion.
Confrontational testing has been discussed earlier for intrinsic
muscles but could also be done to diagnose nerve function
impairment and differentiate between high and low lesions.
For the ulnar nerve, the DIPs of both little fingers could be
“hooked,” distal phalanges interlaced, and strength assessed.
Likewise, the same could be done with FPL (thumb IP
flexion) to assess high median nerve motor integrity.23
14
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
Thumb Extrinsic Muscle Test: EPL
The EPL is the primary extensor of the thumb IP joint. The
EPL is tested by asking the subject to place the palm on a
table surface and lift the thumb above the plane of the hand
(Figures 17a, 17b).47 The thenar muscles, except for the OP,
have an insertion into the extensor apparatus of the thumb.
This insertion is similar to the insertion of the lumbrical
and interosseus muscle in the fingers so that these muscles
can assist in thumb IP extension. In cases of complete EPL
rupture or radial palsy, thumb IP extension may still be
complete. Usually IP extension in this circumstance will be
accompanied by adduction of the thumb as the intrinsic
thumb muscles that insert into the extensor apparatus that try
to substitute for loss of EPL function also exert their primary
function.
The clinical significance of this “trick” movement is obvious:
Do not conclude there is normal EPL function or returning
radial nerve function when thumb IP extension is possible.
Thumb Extrinsic Muscle Test: Extensor Pollicis
Brevis (EPB) and APL
Specific movements that isolate EPB and APL function are
difficult. In clinical practice, the grading of these muscles
in cases of nerve pathology is not needed. We refer to main
textbooks on MMST in case the reader should be interested
in testing these muscles.
The three thumb extensor tendons are all easily palpable
and, in most hands, they are also visible as the patient moves
(circles) the thumb. The tendons are the borders of the
anatomical snuffbox on the radial aspect of the thumb.
References
1.
2.
3.
4.
5.
6.
7.
8.
Figure 17a. Thumb Extrinsic Muscle Test.
9.
10.
11.
12.
13.
14.
15.
Medical Research Council. Aids to the Investigation of Peripheral
Nerve Injuries. Special report series no. 282. London: Her Majesty's
Stationary Office; 1954.
Lowman CL. A method of recording muscle tests. Am J Surg.
1927;3:588-91.
Kendall FP, McCreary EK. Muscles: Testingw and Function. 3rd ed.
Baltimore: Williams & Wilkins; 1983.
Brain Go. Aids to the Examination of the Peripheral Nervous System.
City: W.B. Saunders Company; 2000.
James MA. Use of the Medical Research Council muscle
strength grading system in the upper extremity. J Hand Surg Am.
2007;32(2):154-6.
van Brakel WH. Peripheral nerve function assessment. In: Schwarz RJ,
Brandsma W, eds. Surgical Reconstruction and Rehabilitation in Leprosy
and Other Neuropathies. Kathmandu: Ekta Books; 2004.
Brandsma JW, Schreuders TA, Birke JA, Piefer A, Oostendorp R.
Manual muscle strength testing: intraobserver and interobserver
reliabilities for the intrinsic muscles of the hand. J Hand Ther.
1995;8(3):185-90.
Brandsma JW, Schreuders TA. Sensible manual muscle strength testing
to evaluate and monitor strength of the intrinsic muscles of the hand:
a commentary. J Hand Ther. 2001;14(4):273-8.
Daniels L, Worthingham C. Muscle Testing Techniques of Manual
Examination. Philadelphia: W.B. Saunders Company; 1986.
Lamb RL. Manual muscle testing. In: Rothstein JM, ed. Measurements
in Physical Therapy. London: Churchill Livingstone; 1985.
Lynch L. Manual muscle strength testing of the distal muscles. In:
Amundsen LR, ed. Muscle Strength Testing: Instrumented and NonInstrumented Systems. London: Churchill Livingstone; 1990.
Bohannon RW, Walsh S. Nature, reliability, and predictive value of
muscle performance measures in patients with hemiparesis following
stroke. Arch Phys Med Rehabil. 1992;73(8):721-5.
Videler AJ, Beelen A, Aufdemkampe G, de Groot IJ, Van Leemputte
M. Hand strength and fatigue in patients with hereditary motor
and sensory neuropathy (types I and II). Arch Phys Med Rehabil.
2002;83(9):1274-8.
Cuthbert SC, Goodheart GJ, Jr. On the reliability and validity
of manual muscle testing: a literature review. Chiropr Osteopat.
2007;15:4.
Smith LK, Iddings DM, Spencer WA, Harrington PR. Muscle testing,
part 1. Description of numerical index for clinical research. Physiother
Rev. 1961;41:41-99.
Figure 17b. Thumb Extrinsic Muscle Test.
American Society of Hand TherapistsTM • www.asht.org
15
Clinical Assessment Recommendation
Manual Strength Testing of the Muscles of the Hand and Wrist
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
Paternostro-Sluga T, Grim-Stieger M, Posch M, et al. Reliability and
validity of the Medical Research Council (MRC) scale and a modified
scale for testing muscle strength in patients with radial palsy. J Rehabil
Med. 2008;40(8):665-71.
Florence JM, Pandya S, King WM, et al. Intrarater reliability of
manual muscle test (Medical Research Council scale) grades in
Duchenne's muscular dystrophy. Phys Ther. 1992;72(2):115-22;
discussion 122-6.
Brandsma JW, van Brakel WH, Anderson AM, Kortendijk AJ, Gurung
KS, Sunwar SK. Intertester reliability of manual muscle strength
testing in leprosy patients. Lepr Rev. 1998;69(3):257-66.
MacAvoy MC, Green DP. Critical reappraisal of Medical Research
Council muscle testing for elbow flexion. J Hand Surg Am.
2007;32(2):149-53.
van der Ploeg RJ, Oosterhuis HJ, Reuvekamp J. Measuring muscle
strength. J Neurol. 1984;231(4):200-3.
van der Ploeg RJO. Hand-Held Dynamometry [thesis]. Groningen:
University name; 1992.
Roberts AE, Nicholls PG, Maddali P, Van Brakel WH. Ensuring intertester reliability of voluntary muscle and monofilament sensory testing
in the INFIR Cohort Study. Lepr Rev. 2007;78(2):122-30.
Buschbacher R. Side-to-side confrontational strength-testing for
weakness of the intrinsic muscles of the hand. J Bone Joint Surg Am.
1997;79(3):401-5.
de Krom MC, Knipschild PG, Kester AD, Spaans F. Efficacy of
provocative tests for diagnosis of carpal tunnel syndrome. Lancet.
1990;335(8686):393-5.
de Krom MC, Knipschild PG, Kester AD, Spaans F. Testing for carpal
tunnel syndrome. Lancet. 1991;338(8777):1280.
Kuhlman KA, Hennessey WJ. Sensitivity and specificity of carpal
tunnel syndrome signs. Am J Phys Med Rehabil. 1997;76(6):451-7.
Loong SC. The carpal tunnel syndrome: a clinical and
electrophysiological study of 250 patients. Clin Exp Neurol.
1977;14:51-65.
Shivde AJ, Dreizin I, Fisher MA. The carpal tunnel syndrome. A
clinical-electrodiagnostic analysis. Electromyogr Clin Neurophysiol.
1981;21(2-3):143-53.
Jackson DA, Clifford JC. Electrodiagnosis of mild carpal tunnel
syndrome. Arch Phys Med Rehabil. 1989;70(3):199-204.
Khambati FA, Shetty VP, Ghate SD, Capadia GD. Sensitivity and
specificity of nerve palpation, monofilament testing and voluntary
muscle testing in detecting peripheral nerve abnormality, using nerve
conduction studies as gold standard; a study in 357 patients. Lepr Rev.
2009;80(1):34-50.
van Brakel WH, Nicholls PG, Wilder-Smith EP, Das L, Barkataki P,
Lockwood DN. Early diagnosis of neuropathy in leprosy—comparing
diagnostic tests in a large prospective study (the INFIR cohort study).
PLoS Negl Trop Dis. 2008;2(4):e212.
Selles RW, van Ginneken BT, Schreuders TA, Janssen WG, Stam HJ.
Dynamometry of intrinsic hand muscles in patients with CharcotMarie-Tooth disease. Neurology. 2006;67(11):2022-7.
Schreuders TAR, Roebroeck ME, Jaquet J-B, Hovius SER, Stam HJ.
Long-term outcome of muscle strength in patients with ulnar and
median nerve injury: Comparing manual muscle strength testing, grip
and pinch strength dynamometers and a new intrinsic muscle strength
dynamometer. J Rehabil Med. 2004;36:273-8.
Goldman S, Cahalan TD, An KN. The injured upper extremity and
the JAMAR five-handle position grip test. Am J Phys Med Rehabil.
1991;70(6):306-8.
Goldman SB, Brininger TL, Schrader JW, Koceja DM. A review of
clinical tests and signs for the assessment of ulnar neuropathy. J Hand
Ther. 2009;22:209-19; 2010;23(1):84-6; author reply 86-7.
Schmitt WH, Jr., Cuthbert SC. Common errors and clinical
guidelines for manual muscle testing: "the arm test" and other
inaccurate procedures. Chiropr Osteopat. 2008;16:16.
American Society of Hand TherapistsTM • www.asht.org
Additional References
ErasmusMC video on muscle testing
Web album for figures
Author Affiliations
Independent Hand and Leprosy Rehabilitation Consultant,
The Netherlands (Dr. Brandsma); and Department of Rehabilitation
Medicine, Erasmus University Medical Center, Rotterdam,
The Netherlands (Dr. Schreuders).
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
Basmajian JV, DeLuca CJ. Muscles Alive: Their Function Revealed by
Electromyography. 5th ed. Baltimore: Williams and Wilkins; 1985.
Brunnstrom S. Comparative strength of muscles with similar
function; a study on peripheral nerve injuries of the upper extremity.
Physiotherap Rev. 1946;26:59-65.
MacDermid JC. Measurement of health outcomes following tendon
and nerve repair. J Hand Ther. 2005;18(2):297-312.
Schreuders TAR, Roebroeck ME, Jaquet J-B, Hovius SER, Stam
HJ. Measuring the strength of the intrinsic muscles of the hand
in patients with ulnar and median nerve injury; reliability of the
Rotterdam Intrinsic Hand Myometer (RIHM). J Hand Surg (Am).
2004;29A(2):318-24.
Schreuders TA, Selles RW, Roebroeck ME, Stam HJ. Strength
measurements of the intrinsic hand muscles: a review of the
development and evaluation of the Rotterdam intrinsic hand
myometer. J Hand Ther. 2006;19(4):393-401; quiz 402.
Geere J, Chester R, Kale S, Jerosch-Herold C. Power grip, pinch grip,
manual muscle testing or thenar atrophy—which should be assessed
as a motor outcome after carpal tunnel decompression? A systematic
review. BMC Musculoskelet Disord. 2007;8:114.
Brandsma JW, Birke JA, Sims DS, Jr. The Martin-Gruber innervated
hand. J Hand Surg (Am). 1986;11(4):536-9.
Schreuders TA, Roebroeck ME, Jaquet JB, Hovius SE, Stam HJ.
Measuring the strength of the intrinsic muscles of the hand in
patients with ulnar and median nerve injuries: reliability of the
Rotterdam Intrinsic Hand Myometer (RIHM). J Hand Surg (Am).
2004;29(2):318-24.
Brand PW. Clinical Mechanics of the Hand. St. Louis, Toronto,
Princetown: CV Mosby; 1999.
Brand PW. Biomechanics of balance in the hand. J Hand Ther.
1993;6(4):247-51.
Lemmen MH, Schreuders TA, Stam HJ, Hovius SE. Evaluation of
restoration of extensor pollicis function by transfer of the extensor
indicis. J Hand Surg (Br). 1999;24(1):46-9.
Schreuders TA. The quadriga phenomenon: a review and clinical
relevance. J Hand Surg Eur. 2012;37(6):513-22.
Bowman P, Johnson L, Chiapetta A, Mitchell A, Belusko E. The
clinical impact of the presence or absence of the fifth finger flexor
digitorum superficialis on grip strength. J Hand Ther. 2003;16(3):2458.
16