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PHYSIOLOGY OF BALANCE AND COORDINATION

Written by:

AYU NINGTIYAS NUGROHO

030.08.049

Lecturer:

Dr. Nuryani Sidarta, Sp.RM

FACULTY OF MEDICINE TRISAKTI UNIVERSITY

JAKARTA 2011



PREFACE

Praises and thanks to God for all of his help and permit so I can be finished this

paper even by hard effort and long time. For this chances also I want to say thank you very

much for every people who given their hand to help me in the process of writing, they are:

1. dr. Suriptiastuti, DAP&E, MS. The Dean of Faculty of Medicine Trisakti

University.

2. Dr. Nuryani Sidarta, Sp.RM as my Lecturer who has given his valuable guidance,

motivation, suggestion and help, during the writing process of this paper.

3. And all other person who can not be said one by one who has helped me until

finishing perfect.

To make a literature review, we need not only data but also knowledge of language

and I realize that this paper is not yet perfect and still need improvement because of my

limited capability in English. So, constructive critics and suggestions are needed to make

this paper better.

Last, I apologize for all the mistakes I made or misunderstandings stated in this

paper. I hope this paper could be useful to us.

Jakarta, January 2012

Ayu Ningtiyas Nugroho

ABSTRACTi



The ability to maintain balance depends on information that the brain receives from

three different sources the eyes, the muscles and joints, and the vestibular organs in the in-

ner ears. All three of these sources send information in the form of nerve impulses from

sensory receptors, special nerve endings, to your brain.

Each inner ear has a hearing (auditory) component—the cochlea, and a balance

(vestibular) component the vestibular system, consisting of three semicircular canals and a

utricle and saccule. Each of the semicircular canals is located in a different plane in space.

They are located at right angles to each other and to those on the opposite side of the head.

Inside each fluid-filled semicircular canal is a sensory receptor (cupula) attached at

its base. When the head moves, fluid within the semicircular canals stimulates the cupula

and the receptor then sends impulses to the brain about the direction of the movement. The

utricle and saccule work in similar ways. They are structures that consist of sensory cells

that are embedded in a gelatinous structure. Sitting on the gelatinous portion are calcium

carbonate crystals called otoconia. When your body moves up and down or forward and

backward, the added mass of the otoconia cause the sensory cells to bend. This sends im-

pulses to the brain about the direction of the movement.

When the vestibular apparatus on both sides of the head are functioning properly,

they send symmetrical impulses to the brain. That is, the impulses coming from the right

side agree with the impulses coming from the left side.

All of the sensory input concerning balance, from the eyes, from the muscles and

joints, and from the two sides of the vestibular system, is sent to the brainstem, where it is

sorted out and integrated with contributions from other parts of the brain.i



As integration of all the sensory input takes place, the brainstem sends out impulses

along motor-nerve fibers that begin in the brainstem and end in the muscles. These muscles

make your head and neck, your eyes, your legs, and the rest of your body move and allow

you to maintain your balance and have clear vision while you are moving.

Keyword: balance, coordination, vestibular, proprioceptiual, visual.

TABLE OF CONTENT

PREFACE …........................................................................................ i

iii



ABSTRACT …........................................................................................ ii

TABLE OF CONTENT …................................................................. iv

INTRODUCTION …............................................................................. v

CHAPTER I PHYSIOLOGY OF BALANCE AND COORDINATION 1

CHAPTER II BALANCE AND COORDINATION EVALUATION …. 8

CHAPTER III CONCLUSION …....................................................... 17

REFERENCE …........................................................................................... 18

INTRODUCTION

Balance is the ability to maintain your center of gravity over a base of support. In

iv



order to maintain balance one must have adequate control of not only the legs and arms but

also the trunk and head. Although balance is usually referred to as maintaining an upright

position while sitting or standing, balance is needed to complete activities that require

bending, reaching or lifting one foot. Such activities cause a shift in body weight or center

of gravity. A child may try to widen his base of support to maintain his balance, for

example stand with feet apart or sit with legs apart. As a student, one’s balance is

constantly challenged with crowded hallways, maneuvering around and between desks in

the classroom and lunchroom, and participating in activities with one’s peers.

Coordination is the ability to perform smooth, fluid, accurate and controlled

movements. Coordinated movements are characterized by appropriate speed, distance,

direction, rhythm and muscle tension. Coordinated movements are purposeful movements,

not jerky movements, which allow successful transition from one posture or position to

another within a reasonable amount of time. Coordination also deals with the ability to

visualize an object and react appropriately, such as when attempting to catch a ball or write

an assignment (eye-hand coordination). This ability to react appropriately and in a timely

manner also enables a student to respond safely to changes in the environment, such as a

book falling from a shelf.

In order to successfully and safely move through the environment without bumping

into people or objects, or fall down following a weight displacement, one must have

adequate balance and coordination. Movement that is smooth and efficient helps conserve

energy for endurance.

v



CHAPTER I

PHYSIOLOGY OF BALANCE AND COORDINATIONvi



Balance is the ability to maintain the body’s center of mass over its base of support.

A properly functioning balance system allows humans to see clearly while moving, identify

orientation with respect to gravity, determine direction and speed of movement, and make

automatic postural adjustments to maintain posture and stability in various conditions and

activities.

Balance is achieved and maintained by a complex set of sensorimotor control sys-

tems that include sensory input from vision (sight), proprioception (touch), and the vestibu-

lar system (motion, equilibrium, spatial orientation); integration of that sensory input; and

motor output to the eye and body muscles. Injury, disease, or the aging process can affect

one or more of these components.

Coordination is the ability to use the body parts and senses together to produce

smooth efficient movements.

Problems with balance and coordination occur when the cerebellum, i.e. the part of

the brain responsible for the coordination of movements.

1. Sensory input

Maintaining balance depends on information received by the brain from three periph-

eral sources: eyes, muscles and joints, and vestibular organs. All three of these sources

send information to the brain in the form of nerve impulses from special nerve endings

called sensory receptors.

a. Input from the eyes

Sensory receptors in the retina are called rods and cones. When light

strikes the rods and cones, they send impulses to the brain that provide visual

cues identifying how a person is oriented relative to other objects. For example,

1



as a pedestrian walks along a city street, the surrounding buildings appear verti-

cally aligned, and each storefront passed first moves into and then beyond the

range of peripheral vision.

b. Input from the muscles and joints

Proprioceptive information from the skin, muscles, and joints involves

sensory receptors that are sensitive to stretch or pressure in the surrounding tis-

sues. For example, increased pressure is felt in the front part of the soles of the

feet when a standing person leans forward. With any movement of the legs,

arms, and other body parts, sensory receptors respond by sending impulses to

the brain.

The sensory impulses originating in the neck and ankles are especially

important. Proprioceptive cues from the neck indicate the direction in which

the head is turned.

Cues from the ankles indicate the body’s movement or sway relative to

both the standing surface (floor or ground) and the quality of that surface (for

example, hard, soft, slippery, or uneven).

c. Input from the vestibular system

Sensory information about motion, equilibrium, and spatial orienta-

tion is provided by the vestibular apparatus, which in each ear includes the

utricle, saccule, and three semicircular canals. The utricle and saccule detect

gravity (vertical orientation) and linear movement. The semicircular canals,

which detect rotational movement, are located at right angles to each other

and are filled with a fluid called endolymph. When the head rotates in the

2



direction sensed by a particular canal, the endolymphatic fluid within it lags

behind because of inertia and exerts pressure against the canal’s sensory re-

ceptor. The receptor then sends impulses to the brain about movement.

When the vestibular organs on both sides of the head are functioning prop-

erly, they send symmetrical impulses to the brain. (Impulses originating

from the right side are consistent with impulses originating from the left

side)

2. Integration of sensory input

Balance information provided by the peripheral sensory organs eyes, muscles and

joints, and the two sides of the vestibular system is sent to the brain stem. There, it is sorted

out and integrated with learned information contributed by the cerebellum (the coordina-

tion center of the brain) and the cerebral cortex (the thinking and memory center). The

cerebellum provides information about automatic movements that have been learned

through repeated exposure to certain motions. For example, by repeatedly practicing serv-

ing a ball, a tennis player learns to optimize balance control during that movement. Contri-

butions from the cerebral cortex include previously learned information; for example, be-

cause icy sidewalks are slippery, one is required to use a different pattern of movement in

order to safely navigate them.

a. Processing of conflicting sensory input

A person can become disoriented if the sensory input received from his or her

eyes, muscles and joints, or vestibular organs sources conflicts with one another. For

example, this may occur for example, when a person is standing next to a bus that is

pulling away from the curb. The visual image of the large rolling bus may create an

3



illusion for the pedestrian that he or she rather than the bus is moving. However, at

the same time the proprioceptive information from his muscles and joints indicates

that he is not actually moving. Sensory information provided by the vestibular organs

may help override this sensory conflict. In addition, higher level thinking and memo-

ry might compel the person to glance away from the moving bus to look down in or-

der to seek visual confirmation that his body is not moving relative to the pavement.

3. Motor output

As sensory integration takes place, the brain stem transmits impulses to the muscles

that control movements of the eyes, head and neck, trunk, and legs, thus allowing a person

to both maintain balance and have clear vision while moving.

a. Motor output to the muscles and joints

A baby learns to balance through practice and repetition as impulses sent

from the sensory receptors to the brain stem and then out to the muscles form a new

pathway. With repetition, it becomes easier for these impulses to travel along that

nerve pathway a process called facilitation and the baby is able to maintain balance

during any activity. Strong evidence exists suggesting that such synaptic

reorganization occurs throughout a person’s lifetime of adjusting to changing

motion environs.

This pathway facilitation is the reason dancers and athletes practice soarduous-

ly. Even very complex movements become nearly automatic over a period of time.

For example, when a person is turning cartwheels in a park, impulses transmitted

from the brain stem inform the cerebral cortex that this particular activity is appro-

priately accompanied by the sight of the park whirling in circles. With more prac-

4



tice, the brain learns to interpret a whirling visual field as normal during this type of

body rotation. Alternatively, dancers learn that in order to maintain balance while

performing a series of pirouettes, they must keep their eyes fixed on one spot in the

distance as long as possible while rotating their body.

b. Motor output to the eyes

The vestibular system sends motor control signals via the nervous system to the

muscles of the eyes with an automatic function called the vestibuloocular reflex.

When the head is not moving, the number of impulses from the vestibular organs on

the right side is equal to the number of impulses coming from the left side. When the

head turns toward the right, the number of impulses from the right ear increases and

the number from the left ear decreases. The difference in impulses sent from each

side controls eye movements and stabilizes the gaze during active head movements

(e.g., while running or watching a hockey game) and passive head movements (e.g.,

while sitting in a car that is accelerating or decelerating).

The coordinated balance system

The human balance system involves a complex set of sensorimotor control systems.

Its interlacing feedback mechanisms can be disrupted by damage to one or more compo-

nents through injury, disease, or the aging process. Impaired balance can be accompanied

by other symptoms such as dizziness, vertigo, vision problems, nausea, fatigue, and con-

centration difficulties.

The complexity of the human balance system creates challenges in diagnosing and

treating the underlying cause of imbalance. Vestibular dysfunction as a cause of imbalance

offers a particularly intricate challenge because of the vestibular system’s interaction with

5



cognitive functioning, and the degree of influence it has on the control of eye movements

and posture.

CHAPTER II

BALANCE AND COORDINATION EVALUATION

Coordination is evaluated by testing the patient's ability to perform rapidly alternat-

ing and point-to-point movements correctly.

6



Rapidly Alternating Movement Evaluation. Ask the patient to place their hands on

their thighs and then rapidly turn their hands over and lift them off their thighs. Once the

patient understands this movement, tell them to repeat it rapidly for 10 seconds. Normally

this is possible without difficulty. This is considered a rapidly alternating movement.

Dysdiadochokinesis is the clinical term for an inability to perform rapidly alternat-

ing movements. Dysdiadochokinesia is usually caused by multiple sclerosis in adults and

cerebellar tumors in children. Note that patients with other movement disorders (e.g.

Parkinson's disease) may have abnormal rapid alternating movement testing secondary to

akinesia or rigidity, thus creating a false impression of dysdiadochokinesia.Point-to-Point

Movement EvaluationFinger to Finger

Next, ask the patient to extend their index finger and touch their nose, and then

touch the examiner's outstretched finger with the same finger. Ask the patient to go back

and forth between touching their nose and examiner's finger. Once this is done correctly a

few times at a moderate cadence, ask the patient to continue with their eyes closed. Nor-

mally this movement remains accurate when the eyes are closed. Repeat and compare to

the other hand.

Dysmetria is the clinical term for the inability to perform point-to-point movements

due to over or under projecting ones fingers. Next have the patient perform the heel to shin

coordination test. With the patient lying supine, instruct him or her to place their right heel

on their left shin just below the knee and then slide it down their shin to the top of their

foot. Have them repeat this motion as quickly as possible without making mistakes. Have

the patient repeat this movement with the other foot. An inability to perform this motion in

a relatively rapid cadence is abnormal.

7



The heel to shin test is a measure of coordination and may be abnormal if there is

loss of motor strength, proprioception or a cerebellar lesion. If motor and sensory systems

are intact, an abnormal, asymmetric heel to shin test is highly suggestive of an ipsilateral

cerebellar lesion.Dix-Hallpike test

The Dix-Hallpike test or Nylen-Barany test is a diagnostic maneuver used to identi-

fy benign paroxysmal positional vertigo (BPPV).The Dix-Hallpike test is performed with

the patient sitting upright with the legs extended. The patient's head is then rotated by ap-

proximately 45 degrees. The clinician helps the patient to lie down backwards quickly with

the head held in approximately 20 degrees of extension. This extension may either be

achieved by having the clinician supporting the head as it hangs off the table or by placing

a pillow under their upper back. The patient's eyes are then observed for about 45 seconds

as there is a characteristic 5-10 second period of latency prior to the onset of nystagmus. If

rotational nystagmus occurs then the test is considered positive for benign positional verti-

go. During a positive test, the fast phase of the rotatory nystagmus is toward the affected

ear, which is the ear closest to the ground. The direction of the fast phase is defined by the

rotation of the top of the eye, either clockwise or counter-clockwise. Home devices are

available to assist in the performance of the Dix-Hallpike Maneuver for patients with a di-

agnosis of BPPV.There are several key characteristics of a positive test:Latency of onset

(usually 5-10 seconds)Torsional (rotational) nystagmus. If no torsional nystagmus occurs

but there is upbeating or downbeating nystagmus, a central nervous system (CNS) dysfunc-

tion is indicated.Upbeating or downbeating nystagmus. Upbeating nystagmus indicates that

the vertigo is present in the posterior semicircular canal of the tested side. Downbeating

nystagmus indicates that the vertigo is in the anterior semicircular canal of the tested side.



Fatigable nystagmus. Multiple repetition of the test will result in less and less nystagmus.

Reversal. Upon sitting after a positive maneuver the direction of nystagmus should reverse

for a brief period of time.To complete the test, the patient is brought back to the seated po-

sition, and the eyes are examined again to see if reversal occurs. The nystagmus may come

in paroxysms and may be delayed by several seconds after the maneuver is performed.If

the test is negative, it makes benign positional vertigo a less likely diagnosis and CNS in-

volvement should be considered.Pendular reflexes are not brisk but involve less damping

of the limb movement than is usually observed when a deep tendon reflex is elicited. Pa-

tients with cerebellar injury may have a knee jerk that swings forwards and backwards sev-

eral times. A normal or brisk knee jerk would have little more than one swing forward and

one back. Pendular reflexes are best observed when the patient's lower legs are allowed to

hang and swing freelly off the end of an examining table.Gait is evaluated by having the

patient walk across the room under observation. Gross gait abnormalities should be noted.

Next ask the patient to walk heel to toe across the room, then on their toes only, and finally

on their heels only. Normally, these maneuvers possible without too much difficulty.Be

certain to note the amount of arm swinging because a slight decrease in arm swinging is a

highly sensitive indicator of upper extremity weakness.Also, hopping in place on each foot

should be performed.

Walking on heels is the most sensitive way to test for foot dorsiflexion weakness,

while walking on toes is the best way to test early foot plantar flexion weakness.

Abnormalities in heel to toe walking (tandem gait) may be due to ethanol intoxica-

tion, weakness, poor position sense, vertigo and leg tremors. These causes must be exclud-

ed before the unbalance can be attributed to a cerebellar lesion. Most elderly patients have

9



difficulty with tandem gait purportedly due to general neuronal loss impairing a combina-

tion of position sense, strength and coordination. Heel to toe walking is highly useful in

testing for ethanol inebriation and is often used by police officers in examining potential

"drunk drivers".

Tandem gait is a gait (method of walking or running) where the toes of the back

foot touch the heel of the front foot at each step. Neurologists sometimes ask patients to

walk in a straight line using tandem gait as a test to help diagnose ataxia, especially truncal

ataxia, because sufferers of these disorders will have an unsteady gait. However, the results

are not definitive, because many disorders or problems can cause unsteady gait (such as vi-

sion difficulties and problems with the motor neurons or associative cortex). Therefore, in-

ability to walk correctly in tandem gait does not prove the presence of ataxia.Fukuda Test

The "stepping test" was first developed by Fukuda as a test of vestibular function. More re-

cently, the test has been shown to greater reflect somatosensory function. The test is per-

formed by having the patient stand with eyes closed, arms outstretched and wearing ear

muffs. The patient marches in place at the pace of a brisk walk while keeping the eyes

closed. The doctor observes for any rotation that takes place. Rotation of 30 degrees or

more is considered a positive test. The significance of the test is that it suggests the pres-

ence of either faulty kinesthetic sense or tonic neck reflexes (or both). In the low back pain

patient, a positive test is likely a reflection of either faulty kinesthetic sense or faulty tonic

lumbar reflexes.

Next, perform the Romberg test by having the patient stand still with their heels to-

gether. Ask the patient to remain still and close their eyes. If the patient loses their balance,

the test is positive.To achieve balance, a person requires 2 out of the following 3 inputs to

1



the cortex:

1. visual confirmation of position

2. Non-visual confirmation of position (including proprioceptive and vestibular in-

put)

3. A normally functioning cerebellum. Therefore, if a patient loses their balance af-

ter standing still with their eyes closed, and is able to maintain balance with their

eyes open, then this is indicative of pathology in the proprioceptive pathway. This

is a positive Romberg.

To conclude the gait exam, observe the patient rising from the sitting position. Note gross

abnormalities.

CHAPTER III

CONCLUSION

From all facts, observations, and data, we can conclud that the ability to maintain

balance depends on information that the brain receives from three different sources the

eyes, the muscles and joints, and the vestibular organs in the inner ears. All three of these

11



sources send information in the form of nerve impulses from sensory receptors, special

nerve endings, to your brain.

Balance and coordination are evaluated by testing the patient's ability to perform

rapidly alternating and point-to-point movements correctly.

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4. Schatman, V., & Schinke, S. (1993). The effect of divorce on late adolescent and

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relationships. San Francisco: Jossey Bass.

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