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–1 Grading Muscle Strength.
TABLE B–2 Motor Function.
FIGURE B–1 Trapezius, upper portion (C3, 4; spinal accessory nerve). The shoulder is elevated against resistance.
FIGURE B–2 Trapezius, lower portion (C3, 4; spinal accessory nerve). The shoulder is thrust backward against resistance.
FIGURE B–3 Rhomboids (C4, 5; dorsal scapular nerve). The shoulder is thrust backward against resistance.
FIGURE B–4 Serratus anterior (C5–7; long thoracic nerve). The patient pushes hard with outstretched arms; the inner edge of the scapula remains against the thoracic wall. (If the trapezius is weak, the inner edge may move from the chest wall.)
FIGURE B–5 Infraspinatus (C4–6; suprascapular nerve). With the elbow flexed at the side, the arm is externally rotated against resistance on the forearm.
FIGURE B–6 Supraspinatus (C4–6; suprascapular nerve). The arm is abducted from the side of the body against resistance.
FIGURE B–7 Latissimus dorsi (C5–8; subscapular nerve). The arm is adducted from a horizontal and lateral position against resistance.
FIGURE B–8 Deltoid (C5, 6; axillary nerve). Abduction of laterally raised arm (30–75° from body) against resistance.
FIGURE B–9 Pectoralis major, upper portion (C5–8; T1; lateral and medial pectoral nerves). The arm is adducted from an elevated or horizontal and forward position against resistance.
FIGURE B–10 Pectoralis major, lower portion (C5–8; T1; lateral and medial pectoral nerves). The arm is adducted from a forward position below the horizontal level against resistance.
FIGURE B–11 Biceps (C5, 6; musculocutaneous nerve). The supinated forearm is flexed against resistance.
FIGURE B–12 Triceps (C6–8; radial nerve). The forearm, flexed at the elbow, is extended against resistance.
FIGURE B–13 Brachioradialis (C5, 6; radial nerve). The forearm is flexed against resistance while in a neutral position (neither pronated nor supinated).
FIGURE B–14 Extensor digitorum (C7, 8; radial nerve). The fingers are extended at the metacarpophalangeal joints against resistance.
FIGURE B–15 Supinator (C5–7; radial nerve). The hand is supinated against resistance, with arms extended at the side. Resistance is applied by the grip of the examiner’s hand on the patient’s forearm near the wrist.
FIGURE B–16 Extensor carpi radialis (C6–8; radial nerve). The wrist is extended to the radial side against resistance; fingers remain extended.
FIGURE B–17 Extensor carpi ulnaris (C6–8; radial nerve). The wrist joint is extended to the ulnar side against resistance.
FIGURE B–18 Extensor pollicis longus (C7, 8; radial nerve). The thumb is extended against resistance.
FIGURE B–19 Extensor pollicis brevis (C7, 8; radial nerve). The thumb is extended at the metacarpophalangeal joint against resistance.
FIGURE B–20 Extensor indicis proprius (C6–8; radial nerve). The index finger is extended against resistance placed on the dorsal aspect of the finger.
FIGURE B–21 Abductor pollicis longus (C7, 8; T1; radial nerve). The thumb is abducted against resistance in a plane at a right angle to the palmar surface.
FIGURE B–22 Flexor carpi radialis (C6, 7; median nerve). The wrist is flexed to the radial side against resistance.
FIGURE B–23 Flexor digitorum superficialis (C7, 8; T1; median nerve). The fingers are flexed at the first interphalangeal joint against resistance; proximal phalanges remain fixed.
FIGURE B–24 Flexor digitorum profundus (C7, 8; T1; median nerve). The terminal phalanges of the index and middle fingers are flexed against resistance while the second phalanges are held in extension.
FIGURE B–25 Pronator teres (C6, 7; median nerve). The extended arm is pronated against resistance. Resistance is applied by the grip of the examiner’s hand on the patient’s forearm near the wrist.
FIGURE B–26 Abductor pollicis brevis (C7, 8; T1; median nerve). The thumb is abducted against resistance in a plane at a right angle to the palmar surface.
FIGURE B–27 Flexor pollicis longus (C7, 8; T1; median nerve). The terminal phalanx of the thumb is flexed against resistance as the proximal phalanx is held in extension.
FIGURE B–28 Flexor pollicis brevis (C7, 8; T1; median nerve). The proximal phalanx of the thumb is flexed against resistance placed on its palmar surface.
FIGURE B–29 Opponens pollicis (C8, T1; median nerve). The thumb is crossed over the palm against resistance to touch the top of the little finger, with the thumbnail held parallel to the palm.
FIGURE B–30 Lumbricales-interossei, radial half (C8, T1; median and ulnar nerves). The second and third phalanges are extended against resistance; the first phalanx is in full extension. The ulnar has the same innervation and can be tested in the same manner.
FIGURE B–31 Flexor carpi ulnaris (C7, 8; T1; ulnar nerve). The little finger is abducted strongly against resistance as the supinated hand lies with fingers extended on the table.
FIGURE B–32 Abductor digiti quinti (C8, T1; ulnar nerve). The little finger is abducted against resistance as the supinated hand with fingers extended lies on the table.
FIGURE B–33 Opponens digiti quinti (C7, 8; T1; ulnar nerve). With fingers extended, the little finger is moved across the palm to the base of the thumb.
FIGURE B–34 Adductor pollicis (C8, T1; ulnar nerve). A piece of paper grasped between the palm and the thumb is held against resistance with the thumbnail kept at a right angle to the palm.
FIGURE B–35 Dorsal interossei (C8, T1; ulnar nerve). The index and ring fingers are abducted from the midline against resistance as the palm of the hand lies flat on the table.
FIGURE B–36 Palmar interossei (C8, T1; ulnar nerve). The abducted index, ring, and little fingers are adducted to the midline against resistance as the palm of the hand lies flat on the table.
FIGURE B–37 Sartorius (L2, 3; femoral nerve). With the patient sitting and the knee flexed, the thigh is rotated outward against resistance on the leg.
FIGURE B–38 Quadriceps femoris (L2–4; femoral nerve). The knee is extended against resistance on the leg.
FIGURE B–39 Iliopsoas (L1–3; femoral nerve). The patient lies supine with the knee flexed. The flexed thigh (at about 90°) is further flexed against resistance.
FIGURE B–40 Adductors (L2–4; obturator nerve). With the patient on one side with knees extended, the lower extremity is adducted against resistance; the upper leg is supported by the examiner.
FIGURE B–41 Gluteus medius and minimus; tensor fasciae latae (L4, 5; S1; superior gluteal nerve). Testing abduction: With the patient lying on one side and the thigh and leg extended, the uppermost lower extremity is abducted against resistance.
FIGURE B–42 Gluteus medius and minimus; tensor fasciae latae (L4, 5; S1; superior gluteal nerve). Testing rotation: With the patient prone and the knee flexed, the foot is moved laterally against resistance.
FIGURE B–43 Gluteus maximus (L4, 5; S1, 2; inferior gluteal nerve). With the patient prone, the knee is lifted off the table against resistance.
FIGURE B–44 Hamstring group (L4, 5; S1, 2; sciatic nerve). With the patient prone, the knee is flexed against resistance.
FIGURE B–45 Gastrocnemius (L5; S1, 2; tibial nerve). With the patient prone, the foot is plantar-flexed against resistance.
FIGURE B–46 Flexor digitorum longus (S1, 2; tibial nerve). The toe joints are plantar-flexed against resistance.
FIGURE B–47 Flexor hallucis longus (L5; S1, 2; tibial nerve). The great toe is plantar-flexed against resistance. The second and third toes are also flexed.
FIGURE B–48 Extensor hallucis longus (L4, 5; S1; deep peroneal nerve). The large toe is dorsiflexed against resistance.
FIGURE B–49 Extensor digitorum longus (L4, 5; S1; deep peroneal nerve). The toes are dorsiflexed against resistance.
FIGURE B–50 Tibialis anterior (L4, 5; deep peroneal nerve). The foot is dorsiflexed and inverted against resistance applied by gripping the foot with the examiner’s hand.
FIGURE B–51 Peroneus longus and brevis (L5, S1; superficial peroneal nerve). The foot is everted against resistance applied by gripping the foot with the examiner’s hand.
FIGURE B–52 Tibialis posterior (L5, S1; tibial nerve). The plantar-flexed foot is inverted against resistance applied by gripping the foot with the examiner’s hand.