Testing Muscle Function | Clinical Neuroanatomy, 28e | AccessNeurology

Muscle testing depends on a thorough understanding of which muscles are used in performing certain movements. Testing is best performed when the patient is rested, comfortable, attentive, and relaxed.

Prior to testing strength, the examiner should assess muscle bulk (is there muscle atrophy, or hypertrophy and, if so, which muscles are affected?). The examiner should also note fasciculations, if present, and should record the specific muscles in which they are present.

Because several muscles may function similarly, it is not always easy for the patient to contract a single muscle on request. Positioning or fixation of parts can emphasize the contraction of a particular muscle while other muscles of similar function are inhibited. The effect of gravity must be considered because it can enhance or reduce certain movements. Testing of individual muscles is useful for evaluating peripheral nerve and muscle function and dysfunction. The normal or least affected muscles should be tested first to gain the cooperation and confidence of the patient. The strength of the muscle tested should always be compared with that of its contralateral muscle.

The strength of various muscles should also be graded and charted. Scales of various types are used, most commonly grading strength from 0 (no muscle contraction) to 5 (normal).

See Tables B–1 and B–2 and Figures B–1 to B–52. Notice that in all the figures, blue arrows indicate the direction of movement in testing the given muscle. Black arrows indicate the direction of resistance, and the blocks show the site of application of resistance.

TABLE B–1Grading Muscle Strength.

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TABLE B–1 Grading Muscle Strength.

0:

No muscular contraction

1:

A flicker of contraction, either seen or palpated, but insufficient to move joint

2:

Muscular contraction sufficient to move joint horizontally but not against the force of gravity

3:

Muscular contraction sufficient to maintain a position against the force of gravity

4:

Muscular contraction sufficient to resist the force of gravity plus additional force

5:

Normal motor power

Modified from Aids to the Investigation of Peripheral Nerve Inquiries. Her Majesty's Royal Stationary Office. London, UK, 1953.

TABLE B–2Motor Function.

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TABLE B–2 Motor Function.

Action to Be Tested

Muscle

Cord Segment

Nerves

Plexus

Shoulder Girdle and Upper Extremity

Flexion of neck

Extension of neck

Rotation of neck

Lateral bending of neck

Deep neck muscles (sterno-cleidomastoid and trapezius also participate)

C1–4

Cervical

Elevation of upper thorax

Inspiration

Scaleni

Diaphragm

C3–5

Phrenic

Adduction of arm from behind to front

Pectoralis major and minor

C5–8; T1

Pectoral (thoracic; from medial and lateral cords of plexus)

Brachial

Forward thrust of shoulder

Serratus anterior

C5–7

Long thoracic

Elevation of scapula

Medial adduction and elevation of scapula

Levator scapulae

Rhomboids

C3–5

C4, 5

Dorsal scapular

Abduction of arm

Lateral rotation of arm

Supraspinatus

Infraspinatus

C4–6

Suprascapular

Medial rotation of arm

Adduction of arm from front to back

Latissimus dorsi, teres major, and subscapularis

C5–8

Subscapular (from posterior cord of plexus)

Abduction of arm

Lateral rotation of arm

Deltoid

Teres minor

C5, 6

C4, 5

Axillary (from posterior cord of plexus)

Flexion of forearm

Supination of forearm

Adduction of arm

Flexion of forearm

Biceps brachii

Coracobrachialis

Brachialis

C5, 6

C5–7

C5,6

Musculocutaneous (from lateral cord of plexus)

Ulnar flexion of hand

Flexion of all fingers but thumb

Adduction of metacarpal of thumb

Abduction of little finger

Opposition of little finger

Flexion of little finger

Flexion of proximal phalanx, extension of 2 distal phalanges, adduction and abduction of fingers

Flexor carpi ulnaris

Flexor digitorum profundus (ulnar portion)

Adductor pollicis

Abductor digiti quinti

Opponens digiti quinti

Flexor digiti quinti

Interossei

C7, 8; T1

C8, T1

C7, 8; T1

C8,T1

Ulnar (from medial cord of plexus)

Pronation of forearm

Radial flexion of hand

Flexion of hand

Flexion of middle phalanx of index, middle, ring, or little finger

Flexion of hand

Pronator teres

Flexor carpi radialis

Palmaris longus

Flexor digitorum superficalis

C6, 7

C7, 8; T1

Median (C6, 7 from lateral cord of plexus; C8, T1 from medial cord of plexus)

Flexion of terminal phalanx of thumb

Flexion of terminal phalanx of index or middle finger

Flexion of hand

Flexor pollicis longus

Flexor digitorum profundus (radial portion)

C7, 8; T1

Abduction of metacarpal of thumb

Flexion of proximal phalanx of thumb

Opposition of metacarpal of thumb

Flexion of proximal phalanx and extension of the 2 distal phalanges of index, middle, ring, or little finger

Abductor pollicis brevis

Flexor pollicis brevis

Opponens pollicis

Lumbricales (the 2 lateral)

Lubricales (the 2 medial)

C7, 8; T1

C8, T1

Median (C7, 8 from lateral cord of plexus; C8, T1 from medial cord of plexus)

Ulnar

Brachial

Extension of forearm

Flexion of forearm

Radial extension of hand

Extension of phalanges of index, middle, ring, or little finger

Extension of hand

Extension of phalanges of little finger

Extension of hand

Ulnar extension of hand

Triceps brachii and anconeus

Brachioradialis

Extensor carpi radialis

Extensor digitorum

Extensor digiti quanti proprius

Extensor carpi ulnaris

C6–8

C5, 6

C6–8

C7–8

C6–8

Radial (from posterior cord of plexus)

Supination of forearm

Abduction of metacarpal of thumb

Radial extension of hand

Extension of thumb

Radial extension of hand

Extension of index finger

Extension of hand

Supinator

Abductor pollicis longus

Extensor pollicis brevis

Extensor pollicis longus

Extensor indicis proprius

C5–7

C7, 8; T1

C7, 8

C6–8

Radial (from posterior cord of plexus)

Trunk and Thorax

Elevation of ribs

Depression of ribs

Contraction of abdomen

Anteroflexion of trunk

Lateral flexion of trunk

Thoracic, abdominal, and back

T1–L3

Thoracic and posterior lumbosacral branches

Brachial

Hip Gridle and Lower Extremity

Flexion of hip

Flexion of hip (and eversion of thigh)

Extension of leg

Iliopsoas

Sartorius

Quadriceps femoris

L1–3

L2, 3

L2–4

Femoral

Lumbar

Adduction of thigh

Lateral rotation of thigh

Pectineus

Adductor longus

Adductor brevis

Adductor magnus

Gracilis

Obturator externus

L2, 3

L2–4

L3, 4

L2–4

L3, 4

Obturator

Abduction of thigh

Medial rotation of thigh

Flexion of thigh

Gluteus medius and minimus

Tensor fasciae latae

L4, 5; S1

L4, 5

Superior gluteal

Sacral

Lateral rotation of thigh

Piriformis

S1, 2

Abduction of thigh

Gluteus maximus

L4, 5; S1, 2

Inferior gluteal

Lateral rotation of thigh

Obturator internus

Gemelli

Quadratus femoris

L5, S1

L4, 5; S1

Muscular branches from sacral plexus

Flexion of leg (assist in extension of thigh)

Biceps femoris

Semitendinosus

Semimembranosus

L4, 5; S1, 2

L4, 5; S1

Sciatic (trunk)

Sacral

Dorsal flexion of foot

Supination of foot

Extension of toes 2–5

Dorsal flexion of foot

Extension of great toe

Dorsal flexion of foot

Extension of great toe and the 3 medial toes

Tibialis anterior

Extensor digitorum longus

Extensor hallucis longus

Extensor digitorum brevis

L4, 5

L4, 5; S1

Deep peroneal

Plantar flexion of foot in pronation

Peroneus longus and brevis

Gastrocnemius

L5; S1

L5; S1, 2

Superficial peroneal

Tibial

Plantar flexion of foot in supination

Flexion of terminal phalanx of toes II–V

Plantar flexion of foot in supination

Flexion of terminal phalanx of great toe

Flexion of middle phalanx of toes II–V

Flexion of proximal phalanx of great toe

Spreading and closing of toes

Flexion of proximal phalanx of toes

Tibialis posterior and triceps surae

Flexor digitorum longus

Flexor hallucis longus

Flexor digitorum brevis

Flexor hallucis brevis

Small muscles of foot

L5, S1

S1; 2

L5; S1, 2

L5; S1

L5; S1, 2

S1, 2

Tibial

Voluntary control of pelvic floor

Perineal and sphincters

S2–4

Pudendal

Modified and reproduced, with permission, from McKinley JC.

FIGURE B–1

Trapezius, upper portion (C3, 4; spinal accessory nerve). The shoulder is elevated against resistance.

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