Practical No : 21
EXAMINATION OF THE SENSORY & MOTOR SYSTEMS
Examination of the Sensory System
Objectives :
At the end of the practical the student should be able to,
1. List the different sensory modalities and state the instruments / equipment used to test each
of them.
2. Accurately test for the above sensory modalities
3. Illustrate the dermatomal nerve distribution in the body.
4. Describe the physiological basis of testing to detect the sensory level of a lesion.
The Sensory Modalities
Sensation can be divided into
Exteroception
(Eg. Touch, Pain, Temperature)
Proprioception
(Eg. Muscle, joint position)
Interoception
(Eg. Visceral sensation)
Distance reception
(Eg. Smell, Sound, Taste)
The purpose of testing these modalities is,
To demonstrate clearly, the areas of abnormal sensation
To define which modalities are involved within these limits.
To compare the findings with known patterns of abnormal sensation.
Each sensory modality requires specific equipment in order to test them accurately.
Light Touch
Pain
Temperature
Proprioception
Vibration
Cortical localization Two point discrimination Steriognosis
Graphaesthesia
Point localizations
Sensory extinction
Tested with cotton wool
Tested with either a toothpick or a pin
Tested using warm / cool water filled into small glass tubes.
Tested by changing joint positions.
Tested with a vibrating tuning fork
Tested with a divider or two toothpicks applied
simultaneously
- Tested by giving an easily identifiable object like a key.
- Tested by tracing numbers or letters on the skin
- Tested with cotton wool, pin prick
Testing the sensory nervous system
Instruments / equipment
Swabs of cotton wool
Toothpicks
Pins
Tuning fork
Two point discriminator / Divider
Tubes of warm / cold water
Key, coin, pencil
Method -
-
General :
The patient should be relaxed and aware of what he is being examined for.
The patient should be shown each piece of equipment used for testing.
He should be made aware of each sensation prior to testing.
In the process of examination, avoid rhythmicity.
All dermatomes on both sides of the body should be examined.
The sensations should be compared on both sides of the body as well as adjacent
dermatomes.
Touch :
The swab of cotton wool is twisted into a small point.
This point is applied to the patient's forehead and chest to demonstrate the sensation.
The patient is then told to close his eyes and count each time he feels the examiner
touching the cotton wool to the various dermatomes.
The cotton should not be dragged along the skin
-
Pain :
Using the pin or toothpick, the patient is lightly pricked on the forehead or chest, to
familiarize him with the sensation of both the sharp and blunt ends.
As above, the patient closes his eyes and counts when he perceives the sensation.
The examiner should use both sharp and blunt ends and as the patient to differentiate.
He should also report areas of diminished pain sensation.
-
Temperature :
The hot and cold tubes should first be placed on the patient's forehead to identify.
They are then applied at a random sequence to the skin.
The patient with eyes closed, then attempts to distinguish them.
-
Deep pain :
Tested by firmly squeezing over muscles and tendons.
The patient is asked to indicate when the pressure becomes painful.
The examiner gauges if the force applied will be painful in normal people.
-
-
Proprioception :
Usually tested at the proximal interphalangeal joint of the big toe.
The proximal phalanx is fixed by grasping it firmly in the finger and thumb of the
examiner's left hand.
The thumb and forefinger of the right hand grip the terminal phalanx on its lateral
borders.
Avoid contact with the second toe.
Then the terminal phalanx is moved upward or downward by the examiner.
The patient is initially shown the upward and downward movement and told that
they are 'up' or 'down'.
He is then asked to close his eyes and to indicate whether the joint is flexed or
extended by saying 'down' or 'up' respectively.
-
Vibration :
A tuning fork with a frequency of 128 cycles / sec. is vibrated and the handle then
placed on the patient's forehead to indicate the sensation.
The patient is then asked to close his eyes and the vibrating tuning fork is placed on
bony prominences, starting from the dorsum of the terminal phalanx of the big toe.
He is asked to describe the sensation.
The test is positive only if he perceives vibration and not touch or temperature.
-
Cortical sensations :
-

Two-point discrimination,
Tests the ability to distinguish the contact of two separate points applied
simultaneously.
Should determine the minimum distance of separation at which two points
are identified as two distinct stimuli.
This distance is around 3 - 5 mm in the finger pulps and 50 - 100 mm in the
legs or back.

Steriognosis,
Tests the ability to identify objects by palpation.
Requires intact peripheral sensation as well as evocation in the cortex of the
constellation of ideas and memories necessary for recognition.
Is examined by giving the patient an easily identifiable object like a key ot
coin.

Graphaesthesia,
Tests the ability to recognize numbers or letters traced by a blunt object on
the palm of the hand.
This is impaired in lesions of the sensory cortex.

Point Localisation,
Tests the ability of the patient to localize accurately, the point touched with
the head of a pin or toothpick when the eyes are closed.
The eyes are opened and the patient then places his finger on the exact point
where the stimulus was applied.

Sensory extinction
This tests the perception of stimuli at corresponding sites on both sides of
the body.
Initially, the patient should be tested separately on both sides of the body to
rule out any sensory lesions.
It is necessary to demonstrate the stimulus to the patient prior to testing.
Then the stimulus is simultaneously applied to corresponding sites on the
opposite sides of the body.
The patient, with eyes closed, should identify the side (left / right) as well as
the number of stimuli (one / two) applied.
The dermatomal nerve distribution
C2
T2
C3
C4
C4
C5
C5
T2
3
4
5
6
3
5
4
T2
6
7 8
7
8
C6
10
12 11
T1
9
T1
9
C6
12 L1
L2
L1
C8
L2
C7
10
11
S4
C8
S2
L4
L4
C7
S3
L5
L3
S2
S1
L5
L4
S1
L5
Examination of the Motor System
Objectives :
At the end of the practical the student should be able to,
1. List the components tested in the examination of the motor system.
2. Evaluate muscle power according to the Medical Research Council grading system.
3. Perform a complete examination of the motor system
4. Enumerate the clinical signs observed in Upper Motor Neuron lesions and Lower Motor
Neuron lesions, and state the causes for these lesions.
Testing for motor function also involves the basic principles described for examination of any
system.
They are,
Inspection
Muscle bulk
Fasciculation / Fibrillation
Voluntary movements
Involuntary movements
Palpation
Muscle tone
Muscle power
Coordination
Clonus
Reflexes
Gait & Posture
Inspection :
Muscle Bulk
- Is best estimated by Inspection.
- A muscle may be hypertrophic or atrophic.
- Differences in bulk should be observed in corresponding muscles on either side of the body.
- Wasted or atrophic muscles are,
 Smaller, softer, more flabby than normal
when contracted.
 If accompanied by fibrosis, are inelastic and
hard.
 May even form contractures.
- Hypertrophy can be observed in,
 The dominant side of the body as opposed
to the non-dominant side, especially in
manual labourers.
 Response to repeated exercise as in weight
lifting and athletes.
 Pathological conditions such as ‘Duchenne
Muscular Dystrophy’, where it is a
pseudohypertrophy.
 Other myotonic disorders.
- It may be useful to measure the corresponding muscles in both sides of the body using a tape
measure, and then compare the bulk, if there is no visible difference in bulk.
Fasciculation
- This is often visible in wasted muscles.
- It is produced by the spontaneous contraction of large groups of muscle fibres or of whole
motor units.
- The movements are usually of fine amplitude.
- Fasciculations can be elicited by lightly tapping on the muscle concerned.
- These can also be seen in normal individuals after severe exercise etc.
Voluntary movements
- Observe the patient’s voluntary movements and assess whether they are normal or abnormal.
- Clumsy, jerky movements may indicate incoordination.
- Muscle power may also be assessed to a certain degree, by asking the patient to perform limb
movements against gravity.
Involuntary movements
- Careful inspection should be made of any involuntary movement the patient may have.
- These are,
 Tremor
exaggeration of physiological tremor.
Eg. Alcoholics, Thyrotoxicosis, anxiety.
‘Pill rolling’ tremor in Parkinson’s disease
 Myoclonus
Sudden, shock like, contractions
Eg. Epilepsy, falling asleep
 Choreiform movements
Irregular, jerky, semi-purposive and ill-sustained.
 HemiballismusSimilar to chorea, but much more forceful, and are
unilateral.
 Athetoid spasms
Palpation :
Muscle tone
- Is defined as the resistance to passive stretch of a muscle.
- Usually, the manipulation of a limb evokes a slight elastic resistance from the adjacent muscles.
- Before the examination the patient should completely relax.
- Then, various limbs are manipulated by the examiner, until all muscle groups are examined.
- Tone may be increased (Hypertonia) or decreased (Hypotonia).
- Hypertonia
o There may be spasticity or rigidity.
o Spasticity is characterized by a rapid build up of resistance to stretch and as the
stretch continues, there is a sudden ‘give’ followed by a lessening of resistance.
Eg. Clasp-knife effect (seen in lesions of the pyramidal pathway).
o Rigidity is resistance to passive movement which is sustained throughout the entire
range of movement
Eg. ‘Lead-Pipe’ rigidity (seen in extra-pyramidal lesions).
- Hypotonia
o Is the decreased resistance to passive movement.
o Is harder to assess.
Muscle power
- Can be tested either isometrically or isotonically.
- Isometric testing
 The patient is asked to contract a group of
muscles as powerfully as possible.
 Then he should maintain the posture of that
joint while the examiner tries to restore it to its
normal position.
- Isotonic testing
 The patient is asked to put a joint through its
full range of movement using maximal power.
 The examiner opposes this entire range of
movement, trying to prevent its
accomplishment.
- Assessment of muscle power is performed according
to Medical Research Council grading.
Grading
0
Criteria
1
No active contraction
Visible or palpable contraction without active movement
2
Movement which is possible with gravity eliminated
3
Movement which is possible against gravity
4
Movement which is possible against gravity plus
resistance, but which is weaker than normal
Normal power
5
Coordination
- This is the smooth recruitment, interaction and cooperation of separate muscles or groups of
muscles in order to accomplish a specific motor act.
- Loss of coordination is termed “Ataxia”.
- Coordination is achieved by a combination of
 Proprioception from muscles and joints
 Cerebellar function
 State of muscle tone
 Vision (usually compensatory)
- Coordination is tested with the following,
o Finger pointing test
(read. Cerebellar function)
o Heel – shin test
(read. Cerebellar function)
o Draw a straight line on the floor and ask the patient to walk along it.
o Romberg’s test
Is not a test of cerebellar function.
Is a test of sensory ataxia. The patient stands with feet
close together, arms abducted and eyes closed.
Patient may sway and even fall.
Clonus
- This is the term given to a rhythmic series of involuntary muscular contractions evoked by a
sudden stretch of muscle.
- A few beats of clonus maybe elicited in a nervous patient, and may not be significant.
- Sustained clonus, however, reflects exaggerated tendon reflexes as a result of a UMN lesion
- Two forms generally elicited,

Patella Clonus
The patient lies supine with legs
outstretched and relaxed
The examiner places one fist underneath
the patient’s knee and sharply pushes the
patella towards the patient’s foot.

Ankle Clonus
The patient lies supine with legs
outstretched and relaxed
The examiner raises the leg to be
examined, by the knee, right off the bed.
He then, firmly dorsiflexes the patient’s
foot
Reflexes :
A neurological reflex depends on an arc which consists of,
An afferent pathway triggered by stimulating a receptor
An efferent system which activates an effector organ
A communication between these two components
and
Cell body of
Sensory Neuron
Axon of Sensory
Neuron
Dorsal
Root
Receptor ends of sensory neuron
(neuromuscular spindles)
Quadriceps tendon
Synapse
Cell body of
motor neuron
Patellar
Ligament
Axon of motor
neuron
Effector Muscle
(quadriceps
femoris)
Tibia
Ventral Root
Femur
Routine examination should elicit
 Tendon (deep) reflexes in the limbs
 Superficial (cutaneuos) reflexes
Fibula
Tendon Reflexes
- Are most efficiently evoked by a tap from a
tendon hammer.
- The instrument should have a firm but flexible
shaft and should contain most of its weight in its
head, which should preferably be made of metal
and well padded with soft rubber.
- The patient is placed in a comfortable, relaxed
position, which allows the examiner easy access
to the joint where the reflex is to be elicited.
- The muscle being tested should be visible.
- Compare reflexes on both sides.
- Reflexes commonly checked for are,





Knee Jerk (L3, L4)
Ankle Jerk (L5, S1)
Triceps Jerk (C6, C7)
Biceps Jerk (C5, C6)
Supinator Jerk (C5, C6)
-
Quadriceps Femoris contraction
Gastrocnemius, Soleus contraction
Triceps contraction
Biceps contraction
Supination of forearm
If tendon reflexes cannot be elicited, the patient should be asked to relax as well as perform
reinforcing techniques simultaneous with the application of the tendon hammer.
Superficial Reflexes
These are muscular contractions evoked by cutaneous stimulation.
The Plantar Response
- The patient lies supine with his legs extended
- Using the end of a car key or an orange stick, the examiner draws a line slowly along the
lateral border of the foot, from the heel towards the little toe.
- Observe for a ‘flexor’ response with plantar flexion of the great toe as well as the other
toes.
- The stimulus should not cause injury, but should be a noxious stimulus
The Abdominal Reflexes
- The patient should lie warm and relaxed in a supine position.
- The examiner then draws the point of an orange stick lightly and quickly across the
abdomen, from lateral towards the midline.
- Two lines should run parallel to the costal margins and two lines parallel to the inguinal
ligaments.
- Observe for a brisk contraction of the underlying muscles of the anterior abdominal wall.
The Cremasteric Reflex
- Stroking or scratching the inner aspect of the upper part of the thigh in male patients,
provokes an elevation of the testis.
Gait & Posture
These should be ideally observed at the very beginning of the examination, as the patient walks
into the room.
Various types of gait can indicate quite reliably, the condition the patient is suffering from.
Spastic Gait
Patient walks on a narrow base, has difficulty bending knees and drags the
feet along as if glued to the floor.
Stamping Gait
Is the Gait seen in sensory ataxia. Patient raises his foot abnormally high
and very suddenly, jerks it forward and brings it to the ground with a stamp.
Drunken Gait
Seen in cerebellar ataxia. Patients
walk on a broad base, the feet
planted widely apart and placed
irregularly.
Festinant Gait
Characteristic of Parkinson’s
disease. Patient bends forward and
advances with short, shuffling
steps. The arms do not swing.
Waddling Gait
Is likened to the gait of a duck. The
body is usually tilted backwards
with an increase in lumbar
lordosis.. Feet are planted wide
apart and the body sways from side
to side. Seen in proximal
myopathy.
High stepping Gait
Adopted to avoid tripping due to
the toes dragging along the ground
in foot drop.
The festinant gait of
Parkinson's disease
Signs of Upper and Lower Motor Neuron Lesions
Upper Motor Neuron Lesion
 Drift of upper limb
 Weakness with a characteristic






distribution
Increase in tone (spastic type)
Exaggerated tendon reflexes
Extensor plantar response
Loss of abdominal reflexes
No muscle wasting
Normal electrical excitability of muscle
Lower Motor Neuron Lesion








Muscle weakness
Muscle wasting
Hypotonia
Loss of reflexes
Fasciculation
Contractures of muscle
Trophic changes in skin and nails
Fibrillation potentials seen when sampled
electrically
Causes
Causes
- Spinal cord compression
- Subacute combined degeneration of the
cord
- Syringomyelia
- Cerebral infarction
- Vascular disease of the cord
-
Bell's palsy
Poliomyelitis
Cervical and lumbar disc protrusion
Nerve trauma or entrapment
Mononeuritis multiplex