Testing Muscle Function
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.
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 |
Action to Be Tested | Muscle | Cord Segment | Nerves | Plexus |
|---|---|---|---|---|
Shoulder Girdle and Upper Extremity | ||||
Flexion of neck | Deep neck muscles (sternocleidomastoid and trapezius also participate) | C1–4 | Cervical | Cervical |
Extension of neck | ||||
Rotation of neck | ||||
Lateral bending of neck | ||||
Elevation of upper thorax | Scaleni | C3–5 | Phrenic | |
Inspiration | Diaphragm | |||
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 | Levator scapulae | C3–5 | Dorsal scapular | |
Medial adduction and elevation of scapula | Rhomboids | C4, 5 | ||
Abduction of arm | Supraspinatus | C4–6 | Suprascapular | |
Lateral rotation of arm | Infraspinatus | C4–6 | ||
Medial rotation of arm | Latissimus dorsi, teres major, and subscapularis | C5–8 | Subscapular (from posterior cord of plexus) | |
Adduction of arm from front to back | ||||
Abduction of arm | Deltoid | C5, 6 | Axillary (from posterior cord of plexus) | |
Lateral rotation of arm | Teres minor | C4, 5 | ||
Flexion of forearm | Biceps brachii | C5, 6 | Musculocutaneous (from lateral cord of plexus) | |
Supination of forearm | ||||
Adduction of arm | Coracobrachialis | C5–7 | ||
Flexion of forearm | ||||
Flexion of forearm | Brachialis | C5,6 | ||
Ulnar flexion of hand | Flexor carpi ulnaris | C7, 8; T1 | Ulnar (from medial cord of plexus) | |
Flexion of all fingers but thumb | Flexor digitorum profundus (ulnar portion) | C7, 8; T1 | ||
Adduction of metacarpal of thumb | Adductor pollicis | C8, T1 | ||
Abduction of little finger | Abductor digiti quinti | C8, T1 | ||
Opposition of little finger | Opponens digiti quinti | C7, 8; T1 | ||
Flexion of little finger | Flexor digiti quinti | C7, 8; T1 | ||
Flexion of proximal phalanx, extension of 2 distal phalanges, adduction and abduction of fingers | Interossei | C8,T1 | ||
Pronation of forearm | Pronator teres | C6, 7 | Median (C6, 7 from lateral cord of plexus; C8, T1 from medial cord of plexus) | |
Radial flexion of hand | Flexor carpi radialis | C6, 7 | ||
Flexion of hand | Palmaris longus | C7, 8; T1 | ||
Flexion of middle phalanx of index, middle, ring, or little finger | Flexor digitorum superficalis | C7, 8; T1 | ||
Flexion of hand | ||||
Flexion of terminal phalanx of thumb | Flexor pollicis longus | C7, 8; T1 | ||
Flexion of terminal phalanx of index or middle finger | Flexor digitorum profundus (radial portion) | C7, 8; T1 | ||
Flexion of hand | ||||
Abduction of metacarpal of thumb | Abductor pollicis brevis | C7, 8; T1 | Median (C7, 8 from lateral cord of plexus; C8, T1 from medial cord of plexus) | Brachial |
Flexion of proximal phalanx of thumb | Flexor pollicis brevis | C7, 8; T1 | ||
Opposition of metacarpal of thumb | Opponens pollicis | C8, T1 | ||
Flexion of proximal phalanx and extension of the 2 distal phalanges of index, middle, ring, or little finger | Lumbricales (the 2 lateral) Lubricales (the 2 medial) | C8, T1 C8, T1 | Ulnar | |
Extension of forearm | Triceps brachii and anconeus | C6–8 | Radial (from posterior cord of plexus) | |
Flexion of forearm | Brachioradialis | C5, 6 | ||
Radial extension of hand | Extensor carpi radialis | C6–8 | ||
Extension of phalanges of index, middle, ring, or little finger | Extensor digitorum | C7–8 | ||
Extension of hand | ||||
Extension of phalanges of little finger | Extensor digiti quanti proprius | C6–8 | ||
Extension of hand | ||||
Ulnar extension of hand | Extensor carpi ulnaris | C6–8 | ||
Supination of forearm | Supinator | C5–7 | Radial (from posterior cord of plexus) | |
Abduction of metacarpal of thumb | Abductor pollicis longus | C7, 8; T1 | ||
Radial extension of hand | ||||
Extension of thumb | Extensor pollicis brevis | C7, 8 | ||
Radial extension of hand | Extensor pollicis longus | C6–8 | ||
Extension of index finger | Extensor indicis proprius | C6–8 | ||
Extension of hand | ||||
Trunk and Thorax | ||||
Elevation of ribs | Thoracic, abdominal, and back | T1–L3 | Thoracic and posterior lumbosacral branches | Brachial |
Depression of ribs | ||||
Contraction of abdomen | ||||
Anteroflexion of trunk | ||||
Lateral flexion of trunk | ||||
Hip Gridle and Lower Extremity | ||||
Flexion of hip | Iliopsoas | L1–3 | Femoral | Lumbar |
Flexion of hip (and eversion of thigh) | Sartorius | L2, 3 | ||
Extension of leg | Quadriceps femoris | L2–4 | ||
Adduction of thigh | Pectineus | L2, 3 | Obturator | |
Adductor longus | L2, 3 | |||
Adductor brevis | L2–4 | |||
Adductor magnus | L3, 4 | |||
Gracilis | L2–4 | |||
Adduction of thigh | Obturator externus | L3, 4 | ||
Lateral rotation of thigh | ||||
Abduction of thigh | Gluteus medius and minimus | L4, 5; S1 | Superior gluteal | Sacral |
Medial rotation of thigh | ||||
Flexion of thigh | Tensor fasciae latae | L4, 5 | ||
Lateral rotation of thigh | Piriformis | S1, 2 | ||
Abduction of thigh | Gluteus maximus | L4, 5; S1, 2 | Inferior gluteal | |
Lateral rotation of thigh | Obturator internus | L5, S1 | Muscular branches from sacral plexus | |
Gemelli | L4, 5; S1 | |||
Quadratus femoris | L4, 5; S1 | |||
Flexion of leg (assist in extension of thigh) | Biceps femoris | L4, 5; S1, 2 | Sciatic (trunk) | Sacral |
Semitendinosus | L4, 5; S1 | |||
