Motor Exam

Muscle Bulk and Appearance: this assessment is somewhat subjective and quite dependent on the
age, sex and the activity/fitness level of the individual. A frail elderly person, for example, will have
less muscle bulk then a 25 year old body builder.

1. Using your eyes and hands, carefully examine the major muscle groups of the upper and
lower extremities. Palpation of the muscles will give you a sense of underlying mass. The
largest and most powerful groups are those of the quadriceps and hamstrings of the upper
leg (i.e. front and back of the thighs). The patient should be in a gown so that the areas of
interest are exposed.
2. Muscle groups should appear symmetrically developed when compared with their
counterparts on the other side of the body. They should also be appropriately developed,
after making allowances for the patient's age, sex, and activity level.

3. Tremors are a specific type of continuous, involuntary muscle activity that results in limb
movement. Parkinson's Disease (PD), for example, can cause a very characteristic resting
tremor of the hand (the head and other body parts can also be affected) that diminishes
when the patient voluntarily moves the affected limb. Benign Essential Tremor, on the other
hand, persists throughout movement and is not associated with any other neurological
findings, easily distinguishing it from PD.

3. The major muscle groups to be palpated include: biceps, triceps, deltoids, quadriceps and
hamstrings. Palpation should not elicit pain. Interestingly, myositis (a rare condition
characterized by idiopathic muscle inflammation) causes the patient to experience weakness
but not pain.
4. If there is asymmetry, note if it follows a particular pattern. Remember that some allowance
must be made for handedness (i.e. right v left hand dominance).

 Does the asymmetry follow a particular nerve distribution, suggesting a peripheral

motor neuron injury? For example, muscles which lose their LMN inervation become
very atrophic. Is the bulk in the upper and lower extremities similar?
 Spinal cord transection at the Thoracic level will cause upper extremity muscle bulk to
be normal or even increased due to increased dependence on arms for activity,
mobility, etc. However, the muscles of the lower extremity will atrophy due to loss of
innervation and subsequent disuse.
 Is there another process (suggested by history or other aspects of the exam) that has
resulted in limited movement of a particular limb? For example, a broken leg that has
recently been liberated from a cast will appear markedly atrophic

Tone: When a muscle group is relaxed, the examiner should be able to easily manipulate the joint
through its normal range of motion. This movement should feel fluid. A number of disease states may
alter this sensation. For the screening examination, it is reasonable to limit this assessment to only
the major joints, including: wrist, elbow, shoulder, hips and knees.
1. Ask the patient to relax the joint that is to be tested.
2. Carefully move the limb through its normal range of motion, being careful not to maneuver it
in any way that is uncomfortable or generates pain.

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 3. Be aware that many patients, particularly the elderly, often have other medical conditions
that limit joint movement. Degenerative joint disease of the knee, for example, might cause
limited range of motion, though tone should still be normal. If the patient has recently injured
the area or are in pain, do not perform this aspect of the exam.
4. Normal muscle generates some resistance to movement when a limb is moved passively by
an examiner. After performing this exam on a number of patients, you'll develop an
appreciation for the range of normal tone.
5. Increased tone (hypertonicity) results from muscle contraction. At the extreme end is
spasticity, which occurs when the upper motor neuron no longer functions. In this setting, the
affected limb is held in a flexed position and the examiner may be unable to move the joint.
This is seen most commonly following a stroke, which results in the death of the upper motor
neuron cell body in the brain.
6. Flaccidness is the complete absence of tone. This occurs when the lower motor neuron is cut
off from the muscles that it normally innervates.
7. Disorders that do not directly affect the muscles, upper or lower motor neurons can still alter
tone. Perhaps the most common of these is Parkinson's Disease (PD). This is a disorder of the
Extra Pyramidal System (EPS). The EPS normally contributes to initiation and smoothness of
movement. PD causes increased tone, generating a ratchet-like sensation (known as cog
wheeling) when the affected limbs are passively moved by the examiner.
Strength: As with muscle bulk (described above), strength testing must take into account the age,
sex and fitness level of the patient. For example, a frail, elderly, bed bound patient may have muscle
weakness due to severe deconditioning and not to intrinsic neurological disease. Interpretation must
also consider the expected strength of the muscle group being tested. The quadriceps group, for
example, should be much more powerful then the Biceps.

There is a 0 to 5 rating scale for muscle strength:

0/5 No movement
Barest flicker of movement of the muscle, though not enough to move the structure
1/5
to which it's attached.
Voluntary movement which is not sufficient to overcome the force of gravity. For
2/5 example, the patient would be able to slide their hand across a table but not lift it
from the surface.
Voluntary movement capable of overcoming gravity, but not any applied resistance.
3/5 For example, the patient could raise their hand off a table, but not if any additional
resistance were applied.
4/5 Voluntary movement capable of overcoming "some" resistance
5/5 Normal strength
1. Intrinsic muscles of the hand (C 8, T 1): Ask the patient to spread their fingers apart against
resistance (abduction). Then squeeze them together, with your fingers placed in between
each of their digits (adduction). Test each hand separately. The muscles which control
adduction and abduction of the fingers are called the Interossei, innervated by the Ulnar
Nerve.

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2. Flexors of the fingers (C 7, 8, T1): Ask the patient to make a fist, squeezing their hand around
two of your fingers. If the grip is normal, you will not be able to pull your fingers out. Test
each hand separately. The Flexor Digitorum Profundus controls finger flexion and is
innervated by the Median (radial) and Ulnar (medial) Nerves.

3. Wrist flexion (C 7, 8, T 1): Have the patient try to flex their wrist as you provide resistance.
Test each hand separately. The muscle groups which control flexion are innervated by the
Median and Ulnar Nerves.

4. Wrist extension (C 6, 7, 8): Have the patient try to extend their wrist as you provide
resistance. Test each hand separately. The Extensor Radialis muscles control extension and
are innervated by the Radial Nerve. Clinical Correlate: Damage to the radial nerve results in
wrist drop (loss of ability to extend the hand at the wrist). This can occur via any one of a
number of mechanisms. For example, the nerve can be compressed against the humerus for a
prolonged period of time when an intoxicated person loses consciousness with the inside
aspect of the upper arm resting against a solid object (known as a "Saturday Night Palsy").

5. Elbow Flexion (C 5, 6): The main flexor (and supinator) of the forearm is the Brachialis Muscle
(along with the Biceps Muscle). Have the patient bend their elbow to ninety degrees while
keeping their palm directed upwards. Then direct them to flex their forearm while you
provide resistance. Test each arm separately. These muscles are innervated by the
Musculocutaneous Nerve.
6. Elbow Extension (C 7, 8): The main extensor of the forearm is the triceps muscle. Have the
patient extend their elbow against resistance while the arm is held out (abducted at the
shoulder) from the body at ninety degrees. Test each arm separately. The Triceps is
innervated by the Radial Nerve.

7. Shoulder Adduction (C 5 thru T1): The main muscle of adduction is the Pectoralis Major,
though the Latissiumus and others contribute as well. Have the patient flex at the elbow while
the arm is held out from the body at forty-five degrees. Then provide resistance as they try to
further adduct at the shoulder. Test each shoulder separately.

8. Shoulder Abduction (C 5, 6): The deltoid muscle, innervated by the axillary nerve, is the main
muscle of abduction. Have the patient flex at the elbow while the arms is held out from the
body at forty-five degress. Then provide resistance as they try to further abduct at the
shoulder. Test each shoulder separately.

9. Hip Flexion (L 2, 3, 4): With the patient seated, place your hand on top of one thigh and
instruct the patient to lift the leg up from the table. The main hip flexor is the Iliopsoas
muscle, innervated by the femoral nerve.

10. Hip Extension (L5, S1): With the patient lying prone, direct the patient to lift their leg off the
table against resistance. Test each leg separately. The main hip extensor is the gluteus
maximus, innervated by inferior gluteal nerve.

11. Hip Abduction (L 4, 5, S1): Place your hands on the outside of either thigh and direct the
patient to separate their legs against resistance. This movement is mediated by a number of

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 muscles.

12. Hip Adduction (L 2, 3, 4): Place your hands on the inner aspects of the thighs and repeat the
maneuver. A number of muscles are responsible for adduction. They are innervated by the
obturator nerve.

13. Knee Extension (L 2, 3, 4): Have the seated patient steadily press their lower extremity into
your hand against resistance. Test each leg separately. Extension is mediated by the
quadriceps muscle group, which is innervated by the femoral nerve.

14. Knee flexion (L 5; S 1, 2): Have the patient rest prone. Then have them pull their heel up and
off the table against resistance. Each leg is tested separately. Flexion is mediated by the
hamstring muscle group, via branches of the sciatic nerve.

15. Ankle Dorsiflexion (L 4, 5): Direct the patient to pull their toes upwards while you provide
resistance with your hand. Each foot is tested separately. The muscles which mediate
dorsiflexion are innervated by the deep peroneal nerve. Clinical Correlate: The peroneal nerve
is susceptible to injury at the point where it crosses the head of the fibula (laterally, below the
knee). If injured, the patient develops "Foot Drop," an inability to dorsiflex the foot.

16. Ankle Plantar Flexion (S 1, S 2). Have the patient "step on the gas" while providing resistance
with your hand. Test each foot separately. The gastrocnemius and soleus, the muscles which
mediate this movement, are innervated by a branch of the sciatic nerve. Plantar flexion and
dorsiflexion can also be assessed by asking the patient to walk on their toes (plantar flexion)
and heels (dorsiflexion).

It is generally quite helpful to directly compare right v left sided strength, as they should more or less
be equivalent (taking into account the handedness of the patient). If there is weakness, try to identify
a pattern, which might provide a clue as to the etiology of the observed decrease in strength. In
particular, make note of differences between:

1. Right v Left
2. Proximal muscles v distal
3. Upper extremities v lower
4. Or is the weakness generalized, suggestive of a systemic neurological disorder or global
deconditioning