D(iv). MOTOR SYSTEM EXAMINATION

Motor system examination includes examination of:

Attitude of the limbs

Bulk/nutrition

Assessment of tone

Examination of power

Reflexes

Coordination

Gait

Reflexes, coordination, and gait have been discussed separately in the successive sections.

ATTITUDE

Attitude is the position of the limbs which it adopts when the patient is in resting position.

In a patient with hemiplegia

Upper limb Lower limb

Adduction at shoulder

Flexion at elbow

Semipronated

Thumb tucked into the palm

Extended at hip and knee

Externally rotated at hip

Foot inverted

Plantar flexed

Few common attitudes

Paraplegia Bilateral lower limbs are:

Extended at hip and knee

Externally rotated at hip

Foot inverted

Plantar flexed

Erb’s palsy On the affected side:

Arm: Adducted and internally rotated

Forearm: Extended and pronated

Wrist: flexed

“Waiter’s tip deformity”

MUSCLE BULK/NUTRITION

Muscle bulk is assessed by inspection as well as measurements at corresponding sites in the

extremities.

Symmetry is important with consideration given to handedness and overall body habitus. Wasting is considered if there is >1 cm reduction on the dominant extremity and >2 cm in the

nondominant extremity. In some areas, just inspection is adequate (thenar eminence, hypothenar

eminence, shoulder) whereas in other areas (thighs, legs, arms and forearms) measurement is

required.

Measurements of the circumferences of the limb are done at corresponding areas at fixed distances

from bony landmarks, which are part of that limb. Example: 10 cm below the olecranon [Fig.

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6D(iv).1], 10 cm above the medial humeral epicondyle [Fig. 6D(iv).2], 18 cm above the patella, and

10 cm below the tibial tuberosity.

Fig. 6D(iv).1: Measurement of bulk in the forearm.

Fig. 6D(iv).2: Measurement of bulk in the arm.

Causes for Muscle Hypertrophy (Usually in the Calf) [Fig. 6D(iv).3]

True hypertrophy Pseudohypertrophy (due to increased fat in muscle)

Exercise Duchene’s muscular dystrophy

Becker’s muscular dystrophy

Myotonia congenita—Thomson’s disease

Kugelberg Welander spinal muscular atrophy

Hypothyroidism (infantile Hercules/Kocher–Debré–Semelaigne syndrome)

Storage disorders

Localized muscle swelling—muscle hemorrhage, myositis ossificans, abscess, tumor, muscle rupture or cysts (cysticercosis)

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Fig. 6D(iv).3: Pseudohypertrophy of calf muscle.

Causes of Muscle Wasting

Generalized wasting

Proximal wasting Distal wasting

Malignancy

Cachexia

Tuberculosis

Thyrotoxicosis

Addison’s

disease

HIV/AIDS

Motor neuron disease: Juvenile SMA (Kugelberg

Welander)

Muscular dystrophy: FSHD [Fig. 6D(iv).4], limb girdle

dystrophy

Inflammatory myopathies

Brachial plexopathy

Axillary neuropathy

Anterior horn cell disease—polio, motor neuron

disease

Syringomyelia, intramedullary tumors

Peripheral neuropathies—leprosy, Carpal tunnel

syndrome

Myotonic dystrophy

Plexopathies—lower brachial plexus

Arthritis—rheumatoid

Disuse atrophy

Fig. 6D(iv).4: Proximal muscle wasting seen in facioscapulohumeral dystrophy (FSHD).

Causes of hand muscle wasting [Fig. 6D(iv).5]

Anterior horn cell disease Motor neuron disease

Syringomyelia

Polio

Spinal muscular atrophy

Nerve root T1 compression by disc lesion.

Pachymeningitis

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Cervical spondylosis

Syphilitic amyotrophy

C8–T1 tumors

Brachial plexus Pancoast tumor

Thoracic outlet obstruction, cervical rib

Trauma, Klumpke’s paralysis

Other—infiltration, irradiation

Lesions of peripheral nerve (ulnar or median) Trauma

Acute compression (coma, anesthesia, deep sleep)

Chronic compression (entrapment)

Acute ischemia (collagen vascular disease, diabetes)

Muscle disease Myotonic dystrophy

Distal myopathy—Welander, Udd, Miyoshi, Nonaka, Markesbery

Others Rheumatoid arthritis

Disuse atrophy

Rarely—parietal lobe lesions

Fig. 6D(iv).5: Small muscle wasting of the hand.

The Split Hand Sign

It is highly specific for amyotrophic lateral sclerosis (ALS).

It is due to a lesion in the ulnar nerve or the lower trunk, which will cause predominant wasting of first

dorsal interossei and hypothenar muscles with preserved thenar muscles (which are innervated by the

median nerve).

It is called split hand sign as it preferentially affects lateral part of the hand (abductor pollicis brevis

and first dorsal interossei) and spares the medial part of the hand.

This pattern of dissociated wasting does not correspond to a nerve or plexus or root distribution.

This is in contrast to a C8-T1 root lesion, which will cause wasting of both thenar and hypothenar

muscle as both median and ulnar nerves receive C8-T1 innervation.

MUSCLE TONE

Definition

Tone is defined as partial state of contraction of the muscle at rest which is demonstrated by resistance

offered by the muscle to passive movement across the joint.

Tone is examined in the upper limb (wrist and elbow joint) and the lower limb (knee and ankle joint).

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Testing for Tone in the Legs [Figs. 6D(iv).6 and 6D(iv).7]

With the patient relaxed, place your hands on the thigh and roll the whole leg. Observe the movement

of the foot

With the patient in a supine position, place your hands behind the patient’s knee, and lift the leg in a

sudden motion. Observe if the heel drags along the bed. With normal muscle tone, the heel will drag

along the surface of the bed. However, if there is an increased tone or spasticity, the foot may not

make contact with the bed.

Alternatively flex and extend the knee. Feel for the extensors during flexion and flexors during

extension.

Testing for Tone in the Arms [Figs. 6D(iv).8 to 6D(iv).10]

Lift the arm and let it drop. See the speed and smoothness.

At the elbow, check for tone in biceps and triceps. Feel the biceps while extending the arm, and feel

the triceps while flexing the arm.

Fig. 6D(iv).6: Assessment of tone in the lower limbs.

Fig. 6D(iv).7: Assessment of tone in the lower limbs.

At the wrist, take the hand as if to shake it. First pronate and supinate the forearm. Then roll the hand

around at the wrist. This demonstrates cog wheel rigidity [Fig. 6D(iv).11].

Fig. 6D(iv).8: Examining tone of triceps.

Fig. 6D(iv).9: Examining the tone of biceps.

Fig. 6D(iv).10: Examining the tone in the upper limb.

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Fig. 6D(iv).11: Examining for cog wheeling/rigidity.

Abnormalities of Tone

Hypotonia—decreased tone.

Causes:

Lower motor neuron (LMN) disease

Cerebellar disease

Hypothyroidism

Upper motor neuron (UMN) disease in a state of neuronal shock

Chorea

Hypermagnesemia

Down syndrome

Anesthesia and muscle relaxants.

Hypertonia—increased tone. Two principal types:

Spasticity

Rigidity

Spasticity Rigidity

Synonym Clasp-knife Lead-pipe/Cog-wheel

Diseases Pyramidal Extrapyramidal

Pathophysiology Increased gamma activity Increased gamma and alpha activity

Description Tone increased in the initial part of movement

followed by sudden release—clasp-knife effect*

Supination-pronation of the forearm will reveal the

so-called supinator catch

Increased tone present continuously throughout

the complete range of movement—lead-pipe

With associated tremors—cog-wheel**

Muscles

involved

Anti-gravity muscles (flexors in the UL and extensors

in the LL)

Both groups of muscles

Velocity Velocity dependent (more with fast movements) Velocity independent

Associated

features

Hyperreflexia, extensor plantar Tremors, bradykinesia

*Clasp-knife phenomenon: The muscles at rest do not have excessive tone but a brisk stretch will

produce a catch at about mid-length of the muscle followed by a sudden release of the catch and

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relaxation of the muscle. The giving away or the release portion of the clasp-knife phenomenon is due to

the increased firing of the inhibitory Golgi tendon organs. To elicit this phenomenon, the clinician

extends the patient’s knee using a constant velocity, but as the patient’s knee nears full extension, the

muscle tone of the quadriceps muscles increases dramatically and completes the movement, just as the

blade of a pocket knife opens under the influence of its spring.

**Cog-wheel rigidity: Lead pipe rigidity superimposed with tremors (Negro sign).

Causes of hypertonia:

UMN disease—pyramidal and extrapyramidal

Tetanus

Tetany

Strychnine poisoning

Tonic phase of seizure

Catatonia (seen in schizophrenia where there is increased tone for all movements)

Paratonia—altered tone seen in psychiatric diseases and frontal lobe dysfunction which is

characterized by inability to relax the muscle during muscle tone assessment. Can be of two types:

Oppositional paratonia (Gegenhalten)—where the subjects involuntarily resist passive movements

Facilitatory paratonia (Mitgehen)—where the subject involuntarily assists passive movement.

Paratonia is present in bilateral frontal lobe dysfunction and diffuse cerebellar disorders.

Myotonia—Slow relaxation of muscle after voluntary contraction or contraction provoked by muscle

percussion. Examples: myotonic dystrophy, congenital myotonia, hypothyroidism, neuromyotonia

congenita, Issac syndrome [Fig. 6D(iv).12].

Myoedema

Stationary muscle mounding after muscle percussion without electrical muscle activity is called

myoedema. Myoedema is due to prolonged muscle contraction caused by delayed calcium reuptake by

sarcoplasmic reticulum, following local calcium ion release brought out by percussion or pressure.

Can be seen in hypothyroidism, chronic debilitating diseases, severe cachexia as in TB.

MOTOR POWER

Prerequisites

Explain the test and the movements you are planning to do clearly to the patient before performing the

test.

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Fig. 6D(iv).12: Demonstration of myotonia.

Position the patient according to the muscle which is being tested.

State of Muscle during Examination

Fully contracted muscle

Muscle is at maximum advantage (small muscle)

Fully relaxed muscle

Muscle at maximum disadvantage (may detect mild degrees of weakness)

Mid-contracted muscle

Most feasible method

Used for most large muscles

Qualitative Assessment of Weakness (MRC Grading)

Grade 0—no contraction

Grade 1—Flicker or trace of contraction

Grade 2—active movement, with gravity eliminated

Grade 3—active movement against gravity

Grade 4—active movement against gravity and resistance

Grade 5—normal power

Grades 4-, 4, and 4+ may be used to indicate movement against slight, moderate, and strong

resistance, respectively.

Muscle of neck

Flexion of neck

(sternocleidomastoid/platysma)

The patient attempts to flex his neck against resistance while supporting the chest [Fig.

6D(iv).13]

Extensor of neck The patient attempts to extend their neck against resistance; contraction of the trapezius

and other extensor muscles can be seen and felt, and strength of movement can be

judged [Fig. 6D(iv).14]

Upper limb

Supraspinatus—C5 Patient initiates abduction of arm from side against resistance [Fig. 6D(iv).15]

Deltoid—C5 Patient holds his hand at 60° against resistance [Fig. 6D(iv).16]

Infraspinatus—C5 The patient flexes his elbow, examiner holds the elbow to his side, and then attempts

external rotation of the forearm against resistance [Fig. 6D(iv).17]

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Rhomboids—C5 With hands on hip ask the patient to force the elbow backward [Fig. 6D(iv).18]

Serratus anterior—C5, 6, 7 The patient pushes his arms forward against firm resistance [Fig. 6D(iv).19]

Pectoralis major—C6, 7, 8 Placing hand on hip and pressing inward, sternocostal part of muscle can be seen and

felt to contract [Fig. 6D(iv).20]

Raising the arm forward above 90° and attempting to adduct clavicular portion can be

felt

Latissimus dorsi—C7 While palpating muscles ask the patient to cough

Resist the patients attempt to adduct the arm when abducted to above 90° [Fig.

6D(iv).21]

Biceps—C5 Ask the patient to flex at the forearm with hand in supine position, against resistance [Fig.

6D(iv).22]

Brachioradialis—C5,6 The patient is asked to flex the elbow with the forearm midway between pronation and

supination [Fig. 6D(iv).23]

Triceps—C7 The patient attempts to extend elbow against resistance

[Fig. 6D(iv).24]

Extensor carpi radialis longus—

C6, 7

The patient makes a fist and extends the wrist towards the radial side [Fig. 6D(iv).25]

Extensor carpi ulnaris—C7 The patient makes a fist and extends the wrist towards the ulnar side [Fig. 6D(iv).26]

Extensor digitorium—C7 The examiner attempts to flex the patient’s extended fingers at the metacarpophalangeal

joints

[Figs. 6D(iv).27A and B]

Flexor carpi radialis—C6, 7 The examiner attempts to flex the wrist toward the radial side

[Fig. 6D(iv).28]

Flexor carpi ulnaris—C8 Best seen while testing the abductor digiti minimi when it fixes its point of origin [Figs.

6D(iv).29A and B]

Abductor pollicis longus—C8 Patient maintains their thumb in the abduction against the examiner’s resistance [Fig.

6D(iv).30]

Extensor pollicis brevis—C8 The patient attempts to extend the thumb while the examiner attempts to flex it at the metacarpophalangeal joint [Fig. 6D(iv).31]

Extensor pollicis longus—C8 The patient attempts to extend the thumb while the examiner attempts to flex it at the

interphalangeal joint

Opponens pollicis—T1 The patient attempts to touch the little finger with the thumb

[Fig. 6D(iv).32]

Abductor pollicis brevis—T1 Place an object between the thumb and base of forefinger to prevent full adduction

Patient attempts to raise the edge of the thumb vertically against the resistance [Fig.

6D(iv).33]

Flexor pollicis longus—C8 Tested by attempting to extend the distal phalanx of the thumb against resistance, while

holding the proximal phalanx [Fig. 6D(iv).34]

Adductor pollicis—T1 The patient attempts to hold a piece of paper between the thumb and the palmar aspect of

forefinger and examiner tries to pull the paper [Fig. 6D(iv).35]

Lumbricals—C8, T1 The patient tries to flex the extended fingers at the metacarpophalangeal joints

[Fig. 6D(iv).36]

Dorsal interossei The patient attempts to keep the fingers abducted against resistance [Fig. 6D(iv).37]

First dorsal interossei and palmar

interossei

Place the hand flat on table and the patient tries to abduct and adduct the forefinger

against the resistance [Figs. 6D(iv).38 and 6D(iv).39]

Flexor digitorum sublimis—C8 The patient flexes the fingers at the proximal interphalangeal joint against resistance from

the examiner’s fingers placed on the middle phalanx [Fig. 6D(iv).40]

Flexor digitorum profundus—C8 The patient keeps his hand on a flat surface. The examiner holds the middle phalanx

down; the patient flexes the distal phalanx against resistance [Fig. 6D(iv).41]

Flexor digiti minimi—T1 The back of hand is placed on the table and the little finger abducted against resistance.

(often the only sign of an ulnar lesion)

Trunk muscles

Abdominal muscles The recumbent patient attempts to raise his head against resistance [Fig. 6D(iv).43]

Extensors of spine The patient, lying prone, attempts to raise the head and upper part of the chest [Fig.

6D(iv).44]

Lower limb

Iliopsoas—L1, 2, 3 The patient lies supine and attempts to flex the thigh against resistance [Fig. 6D(iv).45]

Adductor femoris—L5, S1

(Adductor magnus, longus and

brevis)

The patient attempts to adduct the leg against resistance

[Fig. 6D(iv).46]

Gluteus medius and minimus—

L2, 3

Patient in prone, flexes the knee, and then forces the foot outward against resistance [Fig.

6D(iv).47]

Gluteus maximus—L5, S1 Patient in prone raises the thigh against resistance with the knee flexed to minimize the

contribution from the hamstrings [Fig. 6D(iv).48]

Hamstrings—L4, 5, S1, 2 (biceps,

semimembranosus, and

semitendinosus)

Patient in prone and attempts to flex the knee against resistance [Fig. 6D(iv).49]

Quadriceps femoris—L3, 4 Patient is supine and extends the knee against resistance [Fig. 6D(iv).50]

Tibialis anterior— L4, 5 The patient dorsiflexes the foot against the resistance of examiner [Fig. 6D(iv).51]

Tibialis posterior—L4 The patient plantar flexes the foot slightly and then tries to invert it against resistance [Fig.

6D(iv).52]

Peronei—L5, S1 The patient everts the foot against resistance [Fig. 6D(iv).53]

Extensor digitorum longus—L5 Patient asked to dorsiflex the foot against resistance [Fig. 6D(iv).54]

Flexor digitorum longus—S1, 2 Patient asked to flex the terminal phalanges against resistance [Fig. 6D(iv).55]

Extensor hallucis longus—L5, S1 Patient asked to dorsiflex the great toe against resistance

[Fig. 6D(iv).56]

Extensor digitorum brevis—S1 The patient dorsiflexes the toes against resistance [Fig. 6D(iv).57]

Fig. 6D(iv).13: Flexion of neck (sternocleidomastoid/platysma).

Fig. 6D(iv).14: Extensor of neck.

Fig. 6D(iv).15: Supraspinatus—C5. Patient initiates abduction of arm from side against resistance.

Fig. 6D(iv).16: Deltoid C5.

Fig. 6D(iv).17: Infraspinatus—C5. Fig. 6D(iv).20: Pectoralis major—C6, 7, 8.

Fig. 6D(iv).18: Rhomboids—C5. Fig. 6D(iv).21: Latissimus dorsi—C7.

Fig. 6D(iv).19: Serratus anterior—C5, 6, 7. Fig. 6D(iv).22: Biceps—C5.

Fig. 6D(iv).23: Brachioradialis—C5, 6.

Fig. 6D(iv).24: Triceps—C7.

Fig. 6D(iv).25: Extensor carpi

radialis longus—C6, 7.

Fig. 6D(iv).26: Extensor carpi

ulnaris—C7.

Figs. 6D(iv).27A and B: Extensor digitorum—C7.

Fig. 6D(iv).28: Flexor carpi radialis—C6, 7.

Figs. 6D(iv).29A and B: Flexor carpi ulnaris—C8.

Fig. 6D(iv).30: Thumb abduction.

Fig. 6D(iv).31: Thumb extension.

Fig. 6D(iv).32: Opponens pollicis—T1.

Fig. 6D(iv).33: Abductor pollicis brevis—T1.

Fig. 6D(iv).34: Thumb flexion. Fig. 6D(iv).37: Dorsal interossei.

Fig. 6D(iv).35: Thumb adduction. Fig. 6D(iv).38: Palmar interossei.

Fig. 6D(iv).36: Lumbricals—C8, T1. Fig. 6D(iv).39: Card test for palmar interossei.

Fig. 6D(iv).40: Flexor digitorum sublimis. Fig. 6D(iv).43: Abdominal muscles T5–L1.

Fig. 6D(iv).41: Flexor digitorum profundus. Fig. 6D(iv).44: Extensors of spine.

Fig. 6D(iv).42: Abductor digiti minimi. Fig. 6D(iv).45: Iliopsoas—L1, 2, and 3.

Fig. 6D(iv).46: Adductor femoris—L5, S1.

Fig. 6D(iv).47: Gluteus medius and minimus—L2, 3.

Fig. 6D(iv).48: Gluteus maximus—L5, S1.

Fig. 6D(iv).49: Hamstrings—L4, 5, S1, 2 (biceps,

semimembranosus, and semitendinosus).

Fig. 6D(iv).50: Quadriceps femoris—L3, 4.

Fig. 6D(iv).51: Tibialis anticus—L4, 5.

Fig. 6D(iv).52: Tibialis posticus—L4. Fig. 6D(iv).55: Flexor digitorum longus—S1, 2.

Fig. 6D(iv).53: Peronei—L5, S1. Fig. 6D(iv).56: Extensor hallucis longus—L5, S1.

Fig. 6D(iv).54: Extensor digitorum longus—L5. Fig. 6D(iv).57: Extensor digitorum brevis—S1.

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