Loyola University ChicagoLoyola eCommons

Master's Theses Theses and Dissertations

1960

A Study of Residual Activity in Temporalis MuscleNaishadh ParikhLoyola University Chicago

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A STUDY OF RESIDUAL ACTIVITY IN

TEMPORALIS MUSCLE

11)"

mSHADH PARIIH

A Thesis Submitted to the Faculty of the Graduate School

of Lo7ola um .... rsity in Part1.al Fa.l!1ll.ment of

the Requ1N1Bnts for the Degree ot

Master of Science

LIFE

laishadh Parikh lias \torn in :BolIDq, India, on April 24, 193,. He

graduated from. the Fellowship High School, BomDa.y, IDdia, and passed the

Seeonda.:r,r School Certificate Examination helcl 87 the 'board of education"

Gove1"DJllent of Boaay, India, in Mq 1949. lroa June 1949 to May 19,1 he

attende4 St. Xaner's College ot Bomb.,. UniTersity, BoBq_ He enrolled at

the Jlair Hospital Dental Colle,e in June 19$1 and completed his studies

reoeiYing the diploma ot Licenoiate in Dental Science (t.D.Se.) in ~ 19;5.

from June 19$$ to Mq 1956 he did. post-lJ"8.duate studies in Orthodontics and.

halt-time intemship 1n Prosthetic Dentistry at the Nair Hospital Dental

College. In Septaber 19,6 he came to lfD1ted State I of America and .ened

as an intem till Joe 1951 at Forsyth Dental IDt1rlu.r7 tor Ch1ldm., Boston,

Massacheusetts. He Deean his ,raduate studies at Loyola thliTersit7 in JWle

1957. ,,)" ~ -

i11

ACKNOWLEDGEMENTS

My .3incere ap?I'6ciation i~ extended to all tho .. e who have in

any way helped me iI~ making this investigation possible, particul­

arly to the following:

I wish to axtend my gratitude to Joseph h. Jarabak, D.D.S.,

Ph.D., Professor of Orthodontics, Loyola University, who, as my

advisor, offered his. invaluable e~idance and supervision during

the course of this investigation.

To Patrick D. Toto, D.D.S., M.S., Associate Professor of Oral

DiagnosiS and Oral Pathology; G. N. Rapp, Ph.D., Professor of Bio­

Chemistry and Physiology; and Y. T. Oester, Ph.D., M.D., Protessor

of Pharmacology; allot Loyola University, tor their many helpful

suggestions. I wish to thank Dra. Toto, Rapp, and O~uter for

servil~ as members of my advisory board.

To Arthur J. Krol, D.D.S., Associate Profesaor of Prosthetic

Dentistry of Loyola University for hiB cooperation in obtaining

edentulous subJeots for this study.

To James A. Fizzell, B.S., 1n E.E., guest lecturer at Loyola

Jniversity School ot Dentistry, for his teohnioal advioe on stat­

istical discipline and apparatus used in this study.

To all of these I aM most sincerely and profoundly greattul.

iv

TABLE or Cat1EN1'S

Chapter Pace

I. DrRODUCTIClh

A. Introductory Rearks and state.nt 0 f the frob1... • • 1 B. BeY1ew of the Lit.rature • • • • • • • • • • • • • • • 2

II. MATERIALS AND METHOOS.

A. Select10n of the Subjects. • • • B. n.ctrodes • • • • • • • • • • • c. Technic tor Electrode Placnen.t. D. Position o£ the Patient. • • • • I. Ilectronio Iqu1pMnt • • • • • • r. Methods. • • • • • • • • • • • • G. Stast18tical DiScipline. • • • •

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

• • • • • • • • • • • • • • • • • • • • •

• • • • • • • • • • • • • • • • • • • • •

1$ 1$ 16 17 18 18 20

III. IIPERIHlmTAL RESULTS I

IV.

V.

VI.

A. General Findings • • • • • • • • • • • • • • • • • • • 33 J. Residual Activ1t7 after the Exerci •• ot Saline

ftMlssissippift • • • • • • • • • • • • • • • • • • • • • 3S O. ...icU.al Activity atter the Exercis. of SWallcnd.nc • • 37 D. 1le8idual Activity after the Exercise ot HaJdaal

0peD1na. • • • • • • • • • • • • • • • • • • • • • • • 39

DISOUSSICIf • • • • • • • • CClfCLUSION AID SmtfARY ••

BIBLICXlRAPBI ••••• • •

v

• • • • • • • • • • • • • • • •

• • • • • • • • • • • • • • • •

• • • • • • • • • • • • • • • •

SS

68

70

LIST OF FIGURES

Pace

1. DUAL ELECTRODES ON THE ANTERI(Jt, MIDDLE, AND POSTERIOR fIBERS OF LEl'1' 'l'EMPatAL MtJ80Ll. • • • • • • • • • • • • • •• 21

2. IlUiXl'fiM'G ElECfRODB JELLY UlDER TftE A!TACKED ELECTROOE WITH A. smJ'GJ • • • • • • • • • • • • • • • • • • • • • • • • •• 22

3. <ll*lTER USED FCIl TSSfiNO SKII RESISTAHCE • • • • • • • • •• 2.3

4. SUBJECT SEATED D TIm PAlUDAl CAGE, SHOONG ELECTRODE TBltMINAL BOX, MIRROR (]f mE STAWL, AND THE POSITION OF THi SUBJECT • • • • • • • • • • • • • • • • • • • • • • • • • •• 24

S. A MIUOR WI'l'B TO latIZONTAt LINE FOR BEAD a3.I:&ftATIOI. • •• 2S

6. THE ELEC'l'ROOOORlPB ~UIPKENT, SHCliING 'tHE P(}lER SUPPLY tDJIT, AMPLIfiER UlIT, CBISTOOlU.PH, AlID TIME BASE MA.RJCER • • • • •• 26

1. CltISTc:x:mA.PH WITH A Fl. rat TIME BASE MA1UtER • • • • • • • • • 6. fIE CESSATICJt OF m ACTIVITY AND THE ONSET 01 THE REST

pwm ••••••••••••••••••••••••• • • • ,. Sm'CH SRoom BEOOBDED (tiE MIJnr!'E UST PERIOD DIVIDED IlftO

POUR EQUAL PARTS. fIFTEEN SECctIDS EACH, AND THE RANDOlf

27

28

SELECTION or ORE SICOND PERIOO FROM EACH PART. • • • • • •• 2,

10. IWIDOMLY SELECTED <lIE SECOND PERIOD SaMID AMPLITUDE AND ftEQUENCy or ~A'ES JIEASUltED FCll THE STATISTICAL ANALYSIS. •• 30

n. 1'1RIfI1R OALLIPImS, ID-PIID& WITH 'l'JIIIfY-THRU TIMES P(MER or ~BIFICATIOI, AND A SCALE. • • • • • • • • • • • • • • • •• 31

12. OAl.'(,II1U.TIOI At f"!i1l MICllOV'OLfS IBPU1' ••••••••••• • • 32

13. GlW'H 810010 A'EIWlE MICROVOLT-SECOtIDS AT R&S'f AFTER THE DIllERilT IXERCISES • • • • • • • • • • • • • • • • • • • • •

14. GRAPH SHcmIMl AVERAGE KICROfOLT-SECOtIDS FROM '!'HE TEMPCIW. MUSCLES DURING (WE MINUTE PERIOD. • • • • • • • • • • • • •• 42

FiiUh Pq.

1,. GRAPH SHOOlO THE VAlUA'fICfi BETWEEN THE AVERAGE MICROVOLT-SEOotms RECaWED J'B.OM EACH SUBJECT AND THEIR AGE. NarE THE VARIATION BETWEEN THE SUBJECTS. • • • •••••••••••• 4l

16. ~rROMIOGftAPH RECORD or SUBJECT IUtIlER EIGHT SHarmm THE USIDO'AL Acmn'Y RCJo1 THE AVl'ERIOR, MIDDLE, AND POOTERIOR rIBERS or THE RIGHT AID LEi"1' TEMPORAL MUSCLES A.T MANDIBULAR REST AF'.l'D THE EXERCISE or SAIDlO "MISSISSIPPI' • • • • • • • 44

11. ILEOTROOOORAPH RECC!lD or S'O'BJIlCT HUMBER EIGHT SHewING THE RESIDUAL AC'l'IVI'l'Y FROM THE ANftIUOR, MIDDLE, AND POSTFltIal FIBERS ~ '1'BE RIGHT ABD lEFT TEMPmAL MUSCLES AT MANDIBULAR lEST .IF'l'ER 'rHE EXERCISE OF SWALLCMINO • • • • • • • • • • • • 4,

18. ILECTROK!cx.utAPH :uccan Of SU'&JBCT lfOMIlI lIGHT gHOONG THE laIDVAL ACTIVITY FROM THE dTERIOR, MIDDLE, AID POSTERIOR nBERS fI THE RIGHT AID LEn' TEKPWL MUSCLES AT KAlDIBUIAR BEST AFTER '1'HE EXERCISE or KAXIMAL OPEIIHG. • • • • • • • • • 46

19. ILEC'fRClUOORAPH RECqtD OF SUBJECT NtJMBiR WIn SH()100 THE RESn:uAL AOTIVI'l'Y fROM THE ANTERIOR, MIDDLE, AND POSTERIOR FIBERS or mE RIGHr ANl) lEFT TEMPClW. JI1SCLES AT MANDIBULAR REST AFTER THE EXERCISE OF SAnNG "MISSISSIPPI" • • • • • • • h1

20. ELEC1'ROOOORAPH RECORD OF STJBJEOT NUMBER NINE SH<NlING THE RESIWAL ACTIVITY FROM THE ANTERIOR, MIDDLE, AND POSTERIOR nBms or THE RIGHT AND LEFT TEMPCllAL MUSCLES AT MANDIBULAR REST AFl'ER THE EXERCISE OF SWALLOONl • • • • • • • • • • • • 48

21. ILECTROMIOORAPH REC<RD OF SUBJECT NUMBER NINE SHCWING THE RESIDtJAL ACTIVI'l'! FRC»l THE ANTERIOR, MIDDLE, AID POSTERIOR nBERS or THE RIGHT AND LEFT TEMPORAL MUSCLES A.T MANDIBULAR REST AFTER THE EXERCISE or MAXIMAL OPElfIJIl •••••••••• 49

22. ELECTROKYOORAPH RECCRD OF SUBJECT BmSER THREE SHCWING THE IISIll1AL A.CTIVITY FROM THE ANTERIOR, MIDDLE, AND PCBTERIOR FIBERS or THE RIGHT AND LEFT TEMPauL JrmSCLES AT MANDIBULAR REST AFTER '1'HE EXERCISE OF SAYING "MISSISSIPPI" • • • • • • • SO

ligure

23. ELECTR<lfYOORAPH RECORD ~ SUBJIDT Hum ER THREE SR(ltI"INQ THE RESIDUAL ACTIVITY FROM THE ANTERIOR, MIDDLE, AlID PCSTERIOR FIBERS OF THE RIGHT ANDIE FT TEMPORAL MUSCLES AT MANDIBULAR REST AFTER TIm ElEROISE or SWALLOWING. • • • • • • • • • •• Sl

24. ELECTRCl4IOORAPR RECCRD OF SUBJTOOT NUMBER THRiE SHOOI«l 'fBi RESIDUAL ACTIVITY mOM THE ANTERIOR. MIDDLE, AND POSTERI<R FIBERS or THE RIGHT AID IEFT TEMPCRAL MUSCLES AT MANDIBUIAR REST AFTER 'm EXERCISE OF MA.XIMAL OFEm:BG. • • • • • • • •• $2

2,. ALTERNATE HIGH AND LOtI VOLTAGE ACTIVnT IN THE MIDDLE AND POOTEBIat rIBERS or THE RIGHT 'IEMPatAt MUSCLE FROM 'lItE • SUBJECT ftUMBER 011. • • • • • • • • • • • • • • • • • • • •• SJ

26. ILWSTRATICH or THE SENSITIVITf 01 THE EIEC'l'ROMIOORAPH EQUlPMBNT. NorE. A. STRAIGHT LINE RECCRDEt BY THE CRYSTOO1U.PB PEN UP TO THE GAIN EIGHT AND PO DEFIBCTIOO DUE TO HIGn oycm AMPLIFIER NOISE AT GAIN TEl • • • • • • • • • • • • • • • •• S4

LIS! or TABIES

Table Page

I. lAME OF SUBJECTS. TBK~ AGE, APPROXIMATE LENG'l'H Qr TIME TREY WERE EDENTULOUS. AND AVEtWlE iDRGI OUTPUT PER SECOND BY THE TEMPORAL MUSCLES • • • • • • • • • • • • • • • • • • • • • •• ~

II. ANALYSIS or VARIANCE TABLE ••.•••• • • • • • • • • • • • • 1S

CHAPTER I

INTRODUC1'I(}J

A. Introductory Remarks and statement of the Problem

Mandibular musclJlature of patients with tull complements of teeth

usually shows no electrical. activity during rest. Jarabak has shown that

this does not neoessarill hold for edentulous subjects. He Observed low

amplitude residual activity resembling fasciculation While the mandible was

at rest in soma of his subjects. This lack of complete cessation of elec­

trioal activity led him to conclude that the mandibular musculature at rest

is rarely devoid of all motor acti v1ty. It further led him to believe that

an edentulous patient I having lost proprioception from the periodontium, is

deprived of a mechanism needed to govem the mandibular posture, and is

therefore constantly seeking a point of reference.

This study was undertaken to establish the prevalenoe of residual motor

aotivity in the temporal Dl\1scles of edentulous subjects. It was .further

planned to attempt to determine how llUoh of this activity was fasciculation

and how II'Il1ch of 1t is idiopathic.

Here are some of the questions we wlll be attempting to gain information

on: Is this behavior me to anomalies in proprioception? Is it due to

altered tonioity? Is it due to stimuli originating in the oentral or periph""

1

2

eral nervous system.? Or, is it due to degenerative changes in the central

nervous system?

B. Review of the Literature

Luigi Gal vani in 1791 was the first to demonstrate that muscle had two

fundamental electrical properties: (1) that muscles contract when electri­

cally stiDtU.lated, and (2) that an electrical current is produced by the

muscle during its contraction.

The earliest observations of electrical response from muscles were made

with a statio needle galvanometer. Later the capillary electrometer and striqJ

galvanometer were u8ed. The currents produoed bT tmlSole activity are osoU­

latory in nature, and these instruments possessed too much inertia to follow

these oscillations aacuratelT. The oathode ray oscUloscope, which is an

inertialess ~stem., vas later adapted to these studies by Erlanger and Gasser

in 1921.

Later in 1929, permanent written records ot the electrical activitT ot

muscles were obtained by means of an instrument called the electromyograph.

The electr~ograph is at present the instrument ot choice for muscle studies.

The electrical activitT from the muscle is received by electrodes attached to

the skin over the nmsole or by needles iIlaerted into the muscle i teelf • The

currents are then relayed to the amplifier which amplifies them several

thousand times. The amplified signals are finally conve;yad to a transducer

from wRich a written record i. obtained.

Pb;ysiolog1aall.7 a •• cle coosits or lM1ndles of JIlUscle fibers call.d.

actor lDlits 1nnern.t.d. lty a single motor neuron. The electrical actirl'"

arising trom. a motor unit 18 call.d an action potential. '!'hen units or

electrical activity. action potentials, are the thines reoorded ~ the

.lect~o,raph.

Adrian and. Br4NIk (~929). Sm1th (1934), Linsdl87 (193S), Hoerer and

1

PIltnalr. (1939). Weddell, le1ast.iI1 and. Pattl. (1941t.), md other., using thi.

instru.aent tound. that relaxed. .sc1. •• show.d no detectaltle electrical activ1t7

It is, n ..... rtlwl ••• , a .uie pby8iol-c1c uSWIIPtion ari81n& troll the

classioal work ot Sherr1ncton 1n 1915 .. that liv. 1IlU8cl •• , •• en thou&h at rut,

are under coutant actiT1t7 call'" tttomt.... The .1ectrOlll70p'aph can not

detect this activitYe

Boet.r. ill his later pul1cation (1941), stat.s that the .triated .sele

is nol'lll8ll.y' under a constant tension even at rest, and reaoved trom the 1.r&n1l­

ence or cradty. .An increase iD tension beTODd what 1a seen is noticeable in

muscle. or _.o1e grou.ps Hrrl.nC to aa1ntain posture as in standiRg, wi1;heat

obdou. I&Oft1IJents.

QUeon and. MUl. (1941) stud1ed. the electrical. respona.. of the flexer

d1g1to:rua 811lt11111. 1IIU.8ole. Thq found that no activity was obtained with

IIlUscle either relaxed OJ' under a tension or twenty grams when the arm was vell

supported. It the arm was not properly supported then spontaneou aotiTitT

was obtained.

4

Bosma and Gellhom (1946) reported that the potentials can be recorded

from the resting muscles. These potentials were not considered true action

potentials, but probably the result of the nerYe impulses which maintain

muscle tone.

Ralston (19$3), while discussing the question of tonus in the skeletal

muscle, states:

"It has been uniformly obserYed that in the relaxed. h1UIaD subjects, sitting or lying down, there is no detectable persistant bacqround o! electrical activity in may IlUscles that have been examined in the trunk, limbs and jaws. These Dscles are elec­trically silent unless the individual tenses them. During easy standing there is no activity in these muscles, even in such postural muscles as the erector spinae, except as follows: it he sways sufficiently, there may be short bursts in the appro­priate muscles restoring position."

In answering the question "what does maintain a sitting or standing posture if not relatively continuous active muscle con­tractions serving to lock the joint in position," he states: "In addition to a variable amount of balancing of body parts on the bony skeleton, tissue elasticity (i.e., passive stretch tension ot the fascial sheets, ligaments and IlUScles) is usually lIIade use of to a significant degree betore Motor unit activity is called into play. It

Joseph, Nightingale and Williams (19$5), during their observations oyer

postural muscles while relaxed and standing, found that potentials ot up t.

7 uv. occurring about 40-50/8ec. are "corded in addition to the potentials

due to noise level of the apparatus, in the relaxed muscles in the lower li_

as weU as over the DOIIT surface of the tibia and over the patella.

They further state:

"The.e electrical fluctuations uy be due to the 'miniature­end-plate potentials' described by Fatt and Katz (19$2). Other

possible sources are the irregular now of ions through the vessels and the thermal agitation of electrons and ions giving rise to phenomena s1m1lar to • thel'11lB1 noise' in resistors and the 'tl1ckers t effects in valves. Wo conclusion to prove these have been found."

tlIf no evidence of motor activity in relaxed muscles can be found even with a very high degree of amplification, it suggests that 'tone', which is said to be present in relaxed muscles, is not dle to small number of motor units' firing oft' in a rotato1'1 manner."

Spontaneous activity is seen in resting muscle in certain neurogenio

diseases. These involuntary contractions are either tasciculations or

s

fibrillations. In 1938, Denny-Brown and Penn,1:>ecicer wrote a paper differ-

entiating these two terms.

ftWperaetivity of motoneurones in diseases such &S progressive Bnsoular

atrophy or UlTot.rophic lateral 8cler08is result. in regularly periodic

discharges of single iapulses bT the motor neuron. These lnvolunt&r1

sustained contractions at rest are muscle fascieu1ations. Its duration,

recorded electrOllTographically, is about eight to twelve m11.liseconds and

it therefore can be recorded with ink-writing osoillographs ot the electro­

encephalograph machine. Its amplitude may be .561 millivolts.

bitches are lo~ .. st discharge rate of spontaneous oontractions observed

in clinical neurology. The latter may be coarse mel clearly Yislble or so

minute as to be revealed only by the amplified and recorded electrical

component ot the twitch. Denervated muscle fibers contract periodicall7

and the confuaed _day of amal1 twitches constitute tnte t1brUlatlon.

In presence of fatigue or excessive loss of sodium chloride, involuntary

6

m.uscular contractions appear. Those due to fatib"Ue are small bursts of

contractions in a fasciculus, and are of a type such as would be caused by

irregular discharge spreading to and through all the nerve bundles in the

fasciculus. Those of myokem1a, associated with the hyperidosis, are of

similar nature, but of more widespread distribution and more extensive

discharge. Both are clearly related to 1III1soular cramp. The prolonged

discharge compared with the single twitoh of fibrillation and fasciculation

of neuron discharge gives the resulting fuo1cular DlOvement a slower undula­

ting appearance.

Hoeler and Putnam (1940) observed no • spastic' innern.tion ot a resting

muscle and concluded that spastic 'tonus' does not exist except as a refiex

innervation facilitated by the general irritabUity. Spastic resistance is

therefore probably to be considered a reflex phenomenon produced by stretching

of a muscle either by the examiner or \)7 the patient h:1.Dt8elt.

Later that year, they studied rigidity. tremor and re!leDs under various

conditions by electrom;yography'. Here they oDserved Parkinsonian tremor

characterized by a continuous slight innerYation of the rigid muscles even

when the 11mb was placed in its most relaxed position. No such constant

innervation has been observed in cases ot spasticity.

'!'hey also Observed that the stretching of a rigid IlUScle by means ot

active or passive movement produces a marked increase in this innervation.

In this respect rigidity resembles spasticity.

low let us rmew the literature ?8rta1ning tG tbe physiol.ogy or the

mastica.tory IN.8Culature, malnl7 tetnpwal muscles, and the physiologic rest

position of the llWldlble. Speaking or the rest position of the mand1ble,

S1cher states:

wrhe reat position is constant in each 1nd1T1dual due to 1nd1vidual.l1fiDd an only slightly variable tonus of the .. t10&\017 lINseles, wblch in their 'reluat1on' allow the mandible to drop slightly, '!'he rest !losition is therefore not 4ependent OD the teeth or on their shape or position but on the IlUculature a..'"ld ascular balance only."

"It 1s tonus of the ust1ca.tory muscles wh1ch does not. allow the mandible to dl."'op [.maar and fixes ind1v1dually the rest posltiOl'1. It the rmutcles rest. they do not relax ent1rely. Instead, a certain percentage of ,tibers of an individual MI.u5cle reMin 1n the .tate of contraction. In spite of the incapabillty ot the striated IIWIcle f'1'bers to nep contracted to any lvngth ot tiM, the muscle as a whole maintains ::r11ght contraction or tension, lIhioh is termed tonus, by il"0UP8 ot fibers rel1ev1ac .ach other in short intervale. For eaoh musole and eaeh indi­v1dual, t.m. tonlls is fairly constant. 11:

1

The introduction of electromy~raphy in dental seience for studying the

behavior of the oral and. tacial II!IUsoulature is very recent. Ko7ers (1949)

first studied the ben.viQr of the masticr~.tory mu.lScles durlnJ£; temporou.n.d1bular

movements and int.roduced electI'OllVQ&rapq in dentistry. Since then JIUU\1 other

scientific invest.i,;: tors bave studied in tb1e tield. of dent1stl'1'.

Perry (1954) 6Uabested tne use of electromyograpbJ an4 surface electrodes

t.o prostbodonUste and. ortbodont1sts to determine the physiologic rest

position. He round that there 18 a minimal amount of electric discharge fro.

a 1I\1sele at its rest~ 1angth wb.1eb 18 associated with tonus. Slight man-

d1bular movements, imperceptible to the observer, are reoorded from the

temporal and masseter muscles with the electro~ograph.

8

Discussing the interpretation of the electrom,ograph records in dental

science, Sichel' (19$4) states:

"The electro~ograph registers the aotion potential of a muscle, that 1s it shows when and how strongly a muscle acts, but it does not and. can not show in 'Which capacity the JlUscle activity occurs. ~ole can oontraot isotonically or isometri. cally. If they contract isotonically, they shorten and retain tension, if they contract isometrically, they tense but do not shorten and thus retain their length."

Moyers (1949, 1950) studied the eleotrical activity of the temporal

MIlsole from three different parts, the anterior, lliddl.e and posterior fibers.

He obsened that the tonus ot tba musole dieplqed, whUe maintaining the

mandible at physiologic rest position, was equal in all parts of the temporal

muscle in normal individuals. In some cases ot mandibular retrogression, the

spike potentials recorded from the posterior fibers of temporal muscle were

greater than those recorded from the Ddddle and anterior fibers of the same

muscle while mandiDular posture is Deing maintained.

MacDougall and Andrew (19$3) studied the behavior of the masseter and

temporal muscles during normal. movements of the lower jaw by eleotrom;yograplq'.

They recorded slight activity at rest, but it was considered to De due to the

tone of the wsale. Thus considering this as the base line, no electrical

activity was recorded when the jaws were at rest. He also observed that

during the movement of closing the jaw against the gravity alone, a slight

, activity was recorded as against closing the jaw with a small object between

the teeth.

Ballard (1955) has discussed the ph1'siologic baokground of the mandibular

posture ~.d movement. He found elect~olraphically that there is a m1n1mua

of electrical activity in the muscles which maintain the mandibular posture

when the individual i8 sitting upright, has tb.e natural position ot the bead,

and is looking straight forward. He believes that the posture is not 1Id.n­

tained as the result ot the reoiprocal activity ot groups ot musoles at

physiological resting to:rms. It the ind1'¥idual is inverted, the mandible

maintains the postural relationship to the JUXilla, but quite o'brtoo.s17

the pattern of IlUScle activity had to be changed. He Mlines that the.

postural position is the property of the central nervous system. In the

majority ot the individuals, the postural position ot the IWldible is main.

tained even during sleep. Thus he prefers the term 'endogenous postural

position' to 'pQ7siological postural position'.

Re further states that the pattern of activity during endogenous poatural

position may not be produced if the individual's head is clamped in a ceph­

alostat or if he is told of what the observer wants. Only by ca.1,'>etul cl1n1oal

observation can the true postural position be found in each individual. and

when found it can then be reproduced for the purpose of recording, radiograpb­

ically or by other meana.

While discussing the physiology of oentric and other jaw relatione,

MD,yers (19$6) states:

"Any patient presenting for complete denture prosthesis has suttered from a poor occlusal history, or he 'Would not be needing prosthetic service. A high percentage of such patients must have practiced various eccentric patterns tor ,..ars prior to the loss ot all their teeth. While the teeth are in the mouth, the periodontal membranes serve as an important source of arferent signal. tor muscle regulation. Once the teeth and the enclosing periodontal membranes are lost, the position ot the mandible is detendned almost solely by the proprioceptors within the muscles and the capsular jOint. It

10

Jarabak (19$7) ob.e1""l'ed the _soular behavior in the mandibular movements

trom rest position in edentulous subjects, IIOst ot whom had worn dentures tor

SODle time that tunotioned through an excessive :l.nterocclusal distance. As a

control group, he used. subjects with good occlusion and whose interocclwsal

distance ranged from two to tour lI11limatera. From the records of the subjeots

with normal occlusion, while stud71ng rest activity, after the letter ~ had

been repeatedl1' spoken, it was gathered that there was complete electrical

sUence in temporal, masseter 8Ild digastric _scles. While studying the

physiologic rest of the same muscles in edentulous subjects, it was found.

that spontaneous hyperactivity woul.d in:variably appear in temporal and digaa., ,

tric -.scles at rest, it subjects had worn dentures which functioned through

an excessive interocclusal distance. Although this hyperactivity continde4

even atter the removal of the denture, it would 'be 1nh1blted only" after

dentures with correct interocclusal space was placed. Bere also, these muscles

took some time to aQapt the .. l ... e. betore the hyperactivity ceased, Jaraba1c

u

also observed tnat this nyperaetivity was maximum while the mandible was at

rest. It either diminished. or disappeared 'With the slow voluntar;y move.nta

of the maniible in either vertical or horizontal direction. From this it 18

obvious that these tremors were present because the muscles did not function

within the perimeter of its normal physiologic lIlUSole length, but that the

tension recordeel 1n the muscle and tanclon proprioceptors are altered due to

the incorrect tnteroce1usal elistance.

Latif (1957) did an electroDJYographic stud1' of the telBPoral DD18Cle on

twenty-five children aged ten to fourteen years, with normal dente-facial

structures. Be observed. that the temporal muscle m.aintained. the mandibular

posture in the piJl'slologic rest1n& position, the posterior fibers taking more

active part than the anterior fibers. lie confirmed the findings of MacDougall

anel Andrew.

Javois (19S6) did the combined study ot electrOl\rograph and cephalometric

roentgenograph of the rest position of the manelible zel tne interocclusal

clearance. Here, first the rest position was established 11>,. the electl'OZQ'Og.

raph and then the cepMloaetric roentgeDOpoaph recorda were obtained. The

pen den~ction for each subject ani eaoil musele was adjusted. so that th4t

m1n1ma.l activ1t,. froll the au8~le was e8.si17 eletined. However, in no case was

the elef'leotion adjusteel to a degree where no activity could be discerned. If

the activity droppecl to a level at which the pen recordael 8. straight line,

the equaliser was adjuteel to obtain some deflection. Once established, the

12

pen denection remained constant wh1.le the two cephalometric radiograph reco

were obtained. In the conclusion he stated that a low level activity 1UY be

recorded electromyographically from. muscles which are prenmably IlBinta1n1ng

posture.

ll1llen (19$6) reoorded two identical. electromyograms of mini1lwl IlW!Icular

activity associated with postural position from. JlWJseter, anterior fib en of

temporal and supraqoid muscles. He found electrical activity coincident with

the postural position of the mandible. He states that the electrom;yogram must

have high sensitivity to record lIIin1al1'I. 1IUscular activity. He states the

possibility of higher canters afrecting the postural position. All muscles

of the group mainta1n~ng the posture work II)'1'1cbronous17.

LEmmie I Peery and era- (19,8) also did the eleetrOllTograpld.e .·servat1on

on complete denture patients. TheY' recorded JIdn1mal 1IU.Sculu actiTitT trea

the temporal muscle without the denture. in place. The miniDttua II11scular

activity was obtained with the placement ot the If_soular denture". J. great

deal of muscular acti vi ty was discharged troll the temporal musoles when the

second open denture (nth ten millimeters vertioal displaODlellt) was insertecl.

He feels that this m81' be probao17 a stretch-renex type firing of the nervous

units 1n1tiated 01 the increased vertioal d.ilItensions. It is conceivable that

the afferent signals of this stretch reflex tiring could arise from the

temporomandibular joint or oral DlUcosa as well as the _seles themselves.

Possibly all three contributed to SOISe degree.

13

Speaking of the proprioceptive nerYe endings they said that in normal.

indi"lriduals these are tound not only' within and about the temporomandibular

joint and the su.rrounding musculature, but 8. third group of proprioceptive

fibers are found in the periodontal membranes ot all teeth which direct the

action ot the tet1lpOromandibulsr joint.

Jensa (19,9) studied the face height electromrographically in complete

artifioial denture subjeots. He used oryst.ograph and electronic Urt.egl'8.tor to

reoord the rest potentials troll the anteromedial fibers of the temporal. and.

masseter muscles. Be Observed. the rest potent.ials betore the insertion of

complete artificial dent .... , after wearing the dentures approximately one

week, and an.er wearing them for two to tour months with dentures out ot the

mouth and. in place. Cephalometric radiographs were also taken at the same

time to compare the rest vertical. d1lIlensions. There was no sign1ticant

difference found, in his study, between the rest vertical dimensions of the

face during different reoordings, indioating that the rest vertioal dimension

ot the face is quite stable. All these records were obtained with the head.

and mandible in their natural position as well as when clamped in cephalostat.

He conoluded that there was no 8ign1tioant differenoe between these two

recordings. He also cOIIlp8I'ed the rest vertical dimension of the face, with

the oomplete dentures out of the mouth a.f'ter wearing them for two to tour

months, with the occlusal vertical dimension recorded at the same time with

dentures in place. The potentials recorded showed su.tf'ieient difference in

their magnitude which was smaller during rest than in occlusion. During

this study he also noted that more than half' of his subjects had complete

dentures with a greater than average tnterocclusa.l clearance.

Garnick (19$9) studied the rest position of the mandible both cl1nioallJ

and electromyographically in twenty SUbjects. Electro~ographically he

observed the behavior of the temporal, II&ssater and anterior digastrio DlUsoles.

Establishing the rest position cl1ni~, he reoorded su.ll amplitude

pOtentials which he descri'beci as tonus actirlty. Establishing the rest

position electra.,rograph1cally, be found a wide "resting range" in these

muscles. He defined rest position electrOlQ'ographically as the point or area

where -> the lIIl1.8cular potential vas least. In the majority ot the cases in his

study the temporal 1'I\1sclas were at rest from m.aximal opening to light contact

of the teeth. This range tor the anterior tibers ot the temporal JIlUscle val

17.9 mm. and tor the posterior fibers of' the same muscle was 17.2 nun. It vas

suggested that the changes in the aotivity of the temporal muscles decreaaed

or increased the resting range and indirectly the tree va.y space. He also

observed that the clinically and electrolll'ographically detel"lllined rest

position did not coincide in most cases. In thirteen out ot twenty subjects

the clinical rest position was not even located in the range of min1mal

muscular activity.

CltAPTER n

MA'fERIALS AND MErHOns

A. Seleotion ot Subjeots

The edentulous subjeots ranging in ages from forty to seventy years were

used in this study. The S1lbjects were selected at random from the patients

of the Prosthetic Department of the Loyola University School of Dentistry.

Only those pa.tients were selected who had all their teeth extraoted two

months to one year prior to the testing, because this experiment is designed

to study t~ residual activity of the temporal!s muscle during physiologic

. rest of the mandible in the edentulous patients before placement of the

prosthetic appliance.

B. Electrodes

The literature covers various t,ypes ot electrodes used in electromyog.

raphy'. In this experiment surfaoe s11 ver disc eleotrodes 8 Mm.. in diameter

were used (Fig. 1). Absence of underlying superfioial or adjacent muscle

tissues makes the use ot thls type ot electrode more practical :for the

temporal muscle than needle electrOde. These electrodes were attached over

each temporal muscle ,one in the area of anterior, another on the m1d<.U. and

the third on the posterior fibers (Fig. 1). Thus" each of the three parts

o:f the temporal muscle had an electrode placed over it. The fibers ot this

1,

16

tmlscle are as follows: the anterior fibers are directed vertically down­

wards, the middle fibers obliquely, and the posterior fibers horizontally.

These three areas of tl'e escle were studied during the mandibular movements.

For the topography ot the electrode placement, the patient was asked to close

maximally, the temporal IIlscle was then palpated with fingers. This muscle

"tans" trom the posterior surtace ot the e.1e posteriorly to the anterior

surface of the ear and slightly above it. The anterior and posterior borders

were selected. tor the placement ot the electrodes on the anterior and

posterior fibers respectively while the principal belly of the lI'I1scle was

selected to represent the middle fibers.

c. Technic for Electrode Placement

The skin in the selected area was washed with soap and water, and then

acetone. Then it wu rubbed with electrode jelly to reduce the skin

resistance. Washing the area with soap and water removes the skin oils which

make the sld.n resitance too high for accurate recordings. Frequently, the

area was shaved, if it was found necessary to expose the skin (Fig. 1). Each

electrode was secured to the skin with collodion (Fig. 1). Atter the collodi

dried, electrode jelly was inj ected under the electrode, through a small hole

in the center of it, with a blunt hypodermic needle attached to a syringe

(Fig. 2). Re-.dings were taken with an ohaeter to determine that a skin

resistance of ),000 ohms or less was obtained (Fig. ). A second electrode

11

was attached on three given muscle groups about 1 em. apart from the first

one (Fig. 1). Dual electrodes were placed on the musele instead of using

a single electrode with the ear lobe for the reference electrode. This was

done to reduce the distance between the two electrodes to a minimum, so that

maximum activity could be picked up trom the area with the minimum of inter­

ference trom. the other fibers. Sa pairs of electrodes were used, three

pairs on each temporal muscle. The ground electrode was attached to the lett

arm (Fig. 1).

D. Position of the Patient

The patient was seated in a Faraday cage (Fig. 4). Both, patient and

the cage, were connected to the ground to eliminate extraneous noises which

might mask action potentials from the MUscles. To orient the head on the

Frankfort horizontal plane, a mirror was placed at the eye level on a stand

facing the subject. A horizontal line in the middle of the 1Iirror coincided

with an imaginary line drawn through the center of the pupUs (Fig. 5). The

patient was advised to gap the head in the sa_ position during the record

tracing procedure. Previous research has shown no electrical aotivity in

the temporal muscle at rest when the head was oriented on the Frankfort

horizontal plane.

18

E. Electronic Equipment

The electro de wires from each area were led into the terminal box:

situated inside or the Faraday cage (Fig. 4). 'rom this box, the impulses

were red into the amplifier system of an Offner Encephalograph, Type A, which

was adjusted to record high frequencies. The elect~ograph consists of a

power supply and six amplifier units which record siMultaneously (Fig. 6).

'!'he output signals from these amplifiers pass to the six-pen crystographic

ink writer (Fig. 7). The instrument was calibrated for equal pen denection

at ten microvolt peak input. A paper speed of 2.5 am. per second was used

for all the readings in this experiment. The instrument was calibrated

prior to ea.ch run and a.fter each run. A time base u.rker was connected to

a separate pen affixed to the crystograph. It was adjusted to make a den.c. tion ever" tenth of a second.

F •• thods

In order to establish the correct rest position of the mandible, each

subject was asked to perform three different exercises. The exercises are

as follows:

1. To open and close slowly, then rest for one minute.

2. To say the work "Mississlpp1~r, then rest tor one minute.

3. To swallow, then rest for one minute.

These exercises were selected beeause they are used to establish the

19

physiologic rest position of the mandible clinically. Each exercise was

performed ten times, atter which the subject was asked to rest for one minute.

Complete randowation was employed to d.etermine the sequence of the exercise ••

ElectriaaJ. activity WfI.s recorded from the temporal muscles during these exer­

cises and the ensuing rest periods (.Fig. 6). It was easily possible to

distinguish between the regular activity from the Mascles and the irregular

distrubances in the base line caused by the noises within the amplifier

circuits. Four or five recordings were obtained for each exercise.

It was necessary to reduce the uta te numerical form so that they can

be subjected to appropriate analysis of variance. The activity during

ph;ys101ogic rest of the undible from three parts of the temporal _scle was

recer_d for ene m:1nute. This one m1nute period Was d1 vided into four equal.

parts, i.e., each part consists of tifteen seconds. One-second period was

selected at random from each of these four parts. Thus tour one-second per4-Od1

were selected at random fron a one...umte recording (Fig. 9).

Each wave from this one-second period (Fig. 10) was measured in centi­

meters with a VerDier caliper (Fig. 11). These were added. to get the total

centimeters ot wavers per second. This sum. was divided. by the number of

wavers lIeasured to get the average centimeters par wave. Using calibration

at ten lII1ero-volt peak input, this average cent1meters per wave is changed

into micro-voltage (Fig. 12). MUltiplying this average micro-voltage by the

number of measured waves would give the microvolt-seconds, a unit used for

20

the statistical analysis.

G. Statistical Disoipline

In order to establish the validity of the experiment for statistioal

analysis, a complete randomization was employed to determine the sequence ot

the exercises. The subjeots were selected at random within the oategories

desoribed. The one-seoond sample of tracings were seleoted at random within

the quarter ot a minute following the cessation of the exercise. Duplicate

r~adings were obtained from among four or five trials.

The experiment was designed to reveal the difterenoes caused by

variations from one subject to another. It was also designed to reveal the

differences in the enerlT out?Ut ot right an d lett temporal muscles and ot

the divisions of these temporal muscles. It would also disclose the

differences between the "resting" activities within these muscles following

the three ditferent exercises. It was intended to show whether there was

a.ny change in the activity of these muscles during one minute period following

the three exercises. It would also reveal whatever interactions among these

main effects that might be significant. It was neces:oary to transform the

microvolt-second figures by means of the square root tr8l,1d'o:rm.ation so that

the faluliar analysis of variance scheme could be em.p~ in a valid manner.

The results of this analysis appear in Table II.

<-~.

Dual electrodes on the anterior, m1ddle, and posterior fibers of the left tellpOral 1IIU.sele.

21

Injecting electrode jelly under the attached electrode with a syringe.

Ohmmeter used tor te~1ng skin resistanoe.

23

Subject seated in the Faraday cage showin&: A. neetrod.e tendnal bc. B. Mirror on the stand. C. Position ot the sUbject.

A mirror with the horizontal line for head orientation.

The electromyograph equipment showing: A.. Power eupoly unit. B. Amplifier urdt. C. Crystograph. D. Time base marker.

26

Figure 1

Cr.ystograph ~dth a pen for time base marker.

27

The cessation of activity and the onset of the rest period.

28

5 4 3 2 ,

·t\ .. <~\\·t, .. ,1.;' .;t:{I.,~':~"'~"t\ 1.;'~1"\" ;"'"'1., ..... '\"'~11.;'.,1.; ... ~~;l,'"~~~.,-~(~1,~.;~(~~.,-~1.;"""(1.,\"\,"'\, ... .,\\\\(L,1i".\\\\1..\"\ VITY

CEASED

RIGHT POSTERiOR TEMPO

HT MIDDLE TEMPORAL

T ANTERIOR

REST MAXIMAL

figure 9

Sketch showing recorded one minute rest period divided into tour equal parts, t1.t\een seconds each, and the random selection of one seoond period from each part.

ACTIVITY CEASED

o

REST BE<iINS

_ ... .."..-r ,r .,.

A

~ .~

15 SEC·

,u. ..,."..

8

"r

30 SEC·

....... L ..

C 45 SEC·

29

.... ."

0 1 MINUTE

J'igure 10

Randomly selected one second period showing amplitude and frequencY' ot va:"es measured for tbe statistical appraisal.

30

Figure U

Vernier calipers, eye-piece with thirty-three times power of magnification and a scale.

31

figure 12

. Callibration of ten miorovolts input.

CHANNEL

F

E

o

c

B

A

CALIBRATION

)2

IQ,.J INPUT

CHAPTER nI

EIPEBIMEtfTAL RESULTS

A. General Findings

Rest action potentials were recorded from the anterior, lIiddle, ancl

posterior fibers ot the right and lett temporal. auseles ot ten edentuloue

subjeots. Four one-seoond tracinas were used tor the statistical anal;ysis

as desoribed. The recorded data were reduced to Dd.crovolt-seoonds as

desoribed. Since 1I8.DT zero readings were present and the ciata to1"Jled a

skewed. distribution, it was necessary to use the transtormation. One unit

was added to the microvolt-seoond and the square root of this total was used.

as the transformed data. '.hble II shows the results ot the statistioal

The oomponent.s ot variance tor this design have shawn that, sinoe the

nsubject.s" and tlB one-seoond flperiocls tf were treated randomly, their .an

squares were to be treated against the error mean square. The means squares

of the ttJESole groups·, "sides", and "activities". which were 'fwd' sources,

were to be treated against their respe cti ve interaction variance.. fhe

asterisks affixed to t.he variance ratio in f JiJle II indicate the dep''' ot

signiticance at conventional levels.

The amount .t residual activity reoorded during mandibular rest varied

'- '.... /.::: . ""' "'"' / '- '. \ I 7 I c.. -r: 'r' /

act1n 1:.7 was reoorded from the anterior and 1I14d.le filters although a low

level activity. averaging about tbrae 1I10J'OYolts at a trequenoy ot about

twenty vaves per second, 1IIU recorded tl"Oll the posterior fiben (n,. 19.

20 aDd 21). Tb1s was the lowest amount of activity ob.el"Y'ed in an;r ot the

subjects, but it was def1n1tely abOYe the nolH leTel of the recording

apparatus. By wq of oon1:.1'&8t, the 1U.'1d.1IIWII activitY' vas reoorded fro. the

posterior tibera of another auDject, ftWItber three, as t1tHen miol'O'9'o1ts

at a frequency of about fifty-tift waves per second (rl,. 23).

There was ttl. full range of aotivity show bet.en the se ... eral mu80.1e

Ift)UPS wh1ch were atu.d1ed. The anter10r group shoved no residual activ1\f

ill Ml11' subjects vh11e the posterior group alw81'. bad ... acttTtty, del as

IIII'1Uooed abcmt, this vas the ,roup W10h displayed. the highest. volta,es

which were reoorded 1n the Whel. study. The a1ddle iJ"OUPot t1bers IhOWecl

SOll8 actlnty 1n .u subjec'li' except t.he one IIImtlonad above, hut the Mghe8't

'ftlue ... ned &8 about ten ld.oruvo1 ta at a tnqueney ot about f1fty wavea

per second.

figure 1) shove the graphical cOlIpar1sOft ot the averq8 energy output

per second at rest ot all _scle groups teUowing thr.e exel'Ci.... J'igure 13

alac shovs the .erage .erg output ot each _ac1e poup at rest toUow1rIg

the dltterent U8J'Ou.S. 11gtU"e 1.4 .hows the _ftnae enera output per .eoond

ot all 1'I\1s01e croups duJ1.Dc rest at different title period. tol101d.ng cessation

ot the aer01... figure 1S shows that there 1a no relation between the ace of

3S

the subject and the energy output by their temporal DIlscles during rest.

Table I shows name ot the subjects, their age, approxi.mate length ot time

theY' were edentulous, and average energy output per second by the temporal

IlUscles.

The following is the summary ot the residual activity atter different

exercises.

B. Residual Activity after the Exercise of Sqing taMississippi"

Action potentials reoorded during mandibular rest atter this exercise

were lower in amplitude in taOst of the patients studied. In subject number

nine.. the temporal muscles were almost relaxed except few bursts of sponta.

neous hfperactivity (Jig. 19). In subject DUDiber six, the right temporal

mscle showed no activity except a few bursts from what appeared to be s1ngle

motor unit potentials. There were about twelve ot these diphasic discbarges

recorded from the posterior fibers. These ceased in twelve seoonds. The

left middle fibers showed a typical single motor unit activity amounting to

fifteen per second.

On the other hand, greater activity was reoorded tor the same MUscle from.

subject llUJIIber three (Fig. 22). The anterior and middle tibers of the lett

temporal mu.scle recorded the activity six and nine microvolts respectively

with the frequency of fitty-seven and forty-seven waves per second respective.

These fibers of right side elicited the activity ranging in the neighborhood

.36

of four microvolts with the frequency of forty-five waves per second. The

posterior fibers in this subject had the activity with little more frequena,y

but little less amplitude than the left posterior fibers. However, the

average amplitude of these posterior fibers was twelve microvolts and the

average frequency was sixty waves per second.

Similar activity but with less frequenoy was also recorded from the

left posterior fibers 1n subject number one. Right posterior fibers showed

the activity of 6.5 microvolt amplitude. The activity recorded from the

left anterior and middle fibers in this subject was very s1mila.r to those

recorded in subject number three. But practioall.7 no aotivity lias shown by

the right anterior and middle fibers. The rest ot the subjects showed

residual activity of low amplitude. All these subjects showed lIOre actirlt7

in the lett temporal mBcle except one who showed more acti'Vi ty in the right

temporal tmlScle.

The residual activity was present throughout the one-minute period.

There was no complete relaxation nor lias there an interruption in activity

between the cessation of this exercise and the onset of the residual activity.

The residual activity decreased in amplitude for the first forty-five to

filty seconds after its onset, and then it either increased a little or

remained at about the same amplitude. There was very little change in

frequency. At no time had this activity completely ceased exce~t once as

mentioned above.

37

c. Residual Activity after the Exercise of Swallowing:

The residual activity at rest recorded after this exercise was more

than that recorded after the exercise ot saying ''Mississippi''. Six subjects.

showed no activity in the right an terior fibers except few bursts thrOUihout

the rest period. Two subjects showed sustained activity whereas the other

two subjects showed irregular activity of high and low amplitude. The lett

anterior fibers showed no activity in four subjects. In three subjects

these fibers showd low voltage activity, one of which had very high

frequency of fifty waves per second. A subject number five was ver" active

with frequency of thirty-three waves per second in these fibers, in two out

of five conseautive records. The activity decreased to zero towards the

end of one minute period. In other three records the:,;. fibers showed no

residual activity. The remaining two subjects showed the activity of four

microvolts with the traquency of forty waves per second.

The right middle fibers in subject number nine showed no activity

(Fig. 20), whereas his left middle fibers showed low activity at the begi.nninll

of the rest period, and it continued to decrease to zero in the next few

seconds. In subject number ten the left middle fibers showed low amplitude

activity with the frequency of about ten wave. per second, but they were

completely relaxed by the end of one minute period and the residual activity

had ceased. The right middle fibers in this subject showed no activity

38

except few bursts here and there. Two subjects had high activity of six

microvol. ta amplitude with the frequency of forty waves per second in the

lett m1dd.le fibers, whereas their right middle fibers had lower activit,.

with the same frequency.

The rema1ning six subjeots had an average aapli tude ot three to four

microvolts with the frequency of twenty to thirt1-five waves per second in

the middle fibers. Three out or these siX subjects had low voltage activit,.

with low frequency in the ri,ht m1ddJ.e fibers. two subjects had low voltage

activity but high frequency of forty-tive waves per second, and one had low

vol tage activity decreasing progressively to urc in thirty seconds in

three out of five records. The other two records showed the activity of

low amplitude with the frequency of tvent,.-tvo waves per second.

All subjects had. continuous but decreasing residual activity in posteri­

or fibers all throughout the one minute period during which the activit,. was

appraised, except one subject, number nine .. whose posterior fibe1"ll ttUie\e4

down within thirt,. seconds after sw9.llowing (Fig. 20). During first thirt.y

seconds these fibers showed lCM activity of five or six waves per 8econd ..

In subject mlmber seven the activity in both groups of posterior fibers was

similar to that in the middle fibers. S::l.1Illlarly, the activity in the lett

posterior fibers waa the Stw:! as that in the left aiddle fibers in subject

nU1Jlber six, and the activit,. in the right posterior fibers was the sam_ ..

39

that in the right middle fibers in subject number ten. In one subjeot,

number one, an irregular pattern of alternately' high and low voltage activity

was observed in the right posterior fibers (Fig. 25). The remaining subjeots

showed the aotivity of eight to ten microvolts with the frequency of thirt7-

five to forty waves per seoond.

D. Residual Aotivity after the Exercise of Maximal Opening

The residual activity recorded during mandibular rest after this

exercise showed similar results to those shown after the exercise of swallow­

ing. The anterior and middle fibers showed more aotivity here than atter the

exercise of swallowing, but the posterior fibers in these subjects showed

less activit7 here than atter the exercise ot swallowing (rig. 13).

Unlike the results observed after the other exercises, here the anterior

fibers were active in all subjects except in two instances where the right

anterior fibers were silent. The left anterior fibers showed some activit"

even in subject number nine which was not seen at rest after other two

exercises. The aotivity in anterior fibers was low in voltage except in two

subjects, numbers three and one, where the activity recorded from the lett

anterior fibers hac average four to five microvolt amplitude.

In subject number seven the middle fibers were more active than the

posterior fibers, so also in subject number nine where the left middle fibers

were more active than the left posterior fibers (Fig. 21). The right

posterior fibers were more active than the right middle fibers. In all

other subjects the posterior fibers were more active than the middle fibers.

Only three subjects had the left middle fibers showing more activity than

the right nuddle fibers, while the other two subjects showed similar activity

in the middle fibers of both sides. The posterior fibers in subject number

nine showed very little or no activity (Fig. 21). The right posterior fibers

in subjects numbers five and six had more activity than the left posterior

fibers, while in all other subjects the left posterior fibers ~ere more

active. Subject number one had similar activity of alternate high and low

voltage in right temporal muscle as was seen after the exeroise of swallowing

(Fig. 25). His left posterior fibers had activity of average fifteen micro­

volts with the frequency of sixty Waves per second.

Graph showing average Id.crovolt ... econds at rest att.er difterent exercises.

o - Average m1crovolt-seconds recorded trOll the right and lett temporal muscles.

x: - Average a1crovolt .. econds "corded troa the anterior fibers ot the temporal lIUSelas ot both sides.

CJ - Average microvolt-seconds recorded trOll the middle tibers of the te1Iporal lIIIUIoles ot both sides.

a - Average microvolt-seconds recorded from the posterior fibers of the temporal muscles ot both sides.

Graph showing anrage lliorovolt-seoonds from the temporal lIN.soles during ODe m1nute period.

..

10 10

o z

9

:3 9 \)! I

~ o ~ 8 ~ u ~

5

0

5

,t,; w 8 IJ « II: w

~ 7 5

15 30 45 60 liME-SECOND

PERIODS

Figure 15

Graph showing the variation bet_en the average miorovolt­seconds recorded tro:a each subject and their age. lote the variation between the subjects.

40~ C3J

35<J

CJ) ~~,..,.. z....,...,...,

0 () w CJ) .... r:"

-~. ~-t---: ~.,J""

:..J 0

~ ~~ () .... ...,-~

-~ ISO .« a> a:: I) w

.~ 100 4P

e C> 50 C

G1 8

Q 4

50 40 45 55 60 65 70

AGE

J'1gure 1$

Fipre 16

Electr~ograph record ot subject number eight showing the residual activity trom the anterior, middle, and posterior fibers of the right and left temPoral IIIl8cles at mandibular rest after the exercise of saying "Mississippi".

, 47 ... -.' . ~ ; • ..s......' .. .. , ., .., 35

... ·;~i'j1.\\'t,.·S ... '.'jl;-~'i .. Ijlj~-m'i'.i'i-MIj" .. '~'\j •• l"ifl.\\'\j~~".""" - _.- _. -'1 .... " 'tl,\1t'f-'1-.'t1 .. ~I ~ 'I '1' .,'1j"t 'ffl l """"~""~"'''~'''~'r ~ I .

::0 " " , .

RIGHT t;,OSTERIOR TEMPORAL '1'

.... ,

RIGHT MIDDLE TEMPORAL

RIGHT ANTERIOR TEMPORAL

LEfT POSTERIO'i, TE~PORAL ~ .. .... ..... ..,'

LEfT MIDDLE .,~ TEMPORAl., -- • oJ. Joo.. ..I .i ..... .,.. .... ........ ... - .... .,.

LEFT A.

ANTERIOR TEMPORAL

Figure 16

Figure 17

JQ.ect~graph record ot sub ject number eight showing tru. residual activity frOll the anterior, middle, and posterior fibers ot the right end le,f't temporal. JIDl801e8 at mandibular rest attar the exeroise ot swallowing.

RIGHT MIDDLE TE~~IU.a::.

R~HT ANTER~ T~M

MIDDLE TE

LEFT ANTERIOR T

Figure 17

Figure 18

Electromyograph record of subject number eight showing the residual activity from the anterior, middle, and posterior fibers ot the right 8.-11& left temporal muscles at mandibular rest after the exercise of maximal opening.

RIGHT ~L.E TEMPORAL

RIGHT ANTERIOR TEMPORAL

UYT POSTERIOR TEMPORAL

LEP'T MIDDLE: TE~ORAL .

LEFT ANTERIOR TEMPORAL

~ll

l1pre 19

Electromrograph record of subject namber nine showing the residual acti~rity from the ant~ri04J middle, and posterior fibers of the ri.ht and left tem;!oral BIlScles at mandibular rest after the exercise of sa:y1.ng "Mississippi".

, "

RIGHT POSTERIOR TEMPORAL

RIGHT MIDDLE TEMPORAL

RIGHT ANTERIOR TEMPORAL

LEFT POSTERIOR TEMPORAL - - ---- - - -------,- --- ----- --------- ---~ ---~ -~ -------------~- -----

LEFT MIDDLE TEMPORAL

LEFT ANTERIOR TEMPORAL -~~~~- - ~--~----~--- -~- -- -----~-----~----

AFTER SAYING 'MISSISSIPPI'

nectromrograph record. of subject number nine showing the residual activit7 from the anterior, middle, and posterior fibers of the right and 18 It temporal IIlScles at 1I18.Tldibular rest atter the exercise of swallowing.

31 36 35 34 33 32 31 30 29. 28 ~ 'i';";:': .;.;.;..-),\-.;.;.;;.; .;~,-.;.; "-l~"''; -..-,"\".; .;-... -.;~.;..-';."-"-"-.,-.,.;:.;.; ...:.;\,-.; .:.;..;.; ;,-.,.. ..-.. -..-.,-.;.; -.;..,-.;.,-.:';';"-.. -.;.,-..-.,-.;.; r . " I . .~, I . . .'. I ~ , '.

, .J ,

RIGHT F OSTEF lOR TEMPORAL

_____ R_IG_H_T __ 1+-ID.D_LE .:~_~~<?RA~ _ _

___ --R-'GHT _' ~TER '~R _TEIAP_,:RAL __ -r----~I I i

f OSTE~IOR TEMPORAL J ---------.-------.-+-- .. ". ..' I I I LEFT

I I I LEfT ~ IDDLE TEMPORAL I I ... ~.~

-~-."",,-'--~~'- .--. - .~-- -' . -·--·\·I~-__t----~·· - I

_________ --LEf-!. __ .. ~!.~~.IOR TEMPOR.~~ .• ~ --l- __ ~ .'TE. IW4LL INO ! i

I

Figure 21

Electromyograph record ot subject number nine showing the residual activity from the anterior, middle, and posterior tibers ot the right and left temporal muscles at mandibular rest after the exercise of maximal opening.

15 14 13 12 II 10 9 8 7 6 5 ~,,~-""S .. -... -... -y,-...-,,-.;-.~.;-,~...-.;-.-.;-...-.; "-... "',, ..; "-... ..;..;..;.; ... ..; ... " , wi " ... ..;\ ... ..; ... ' ..;, " ... ";"-"-';";r\""\-';-:",,!,,'-"'-"'; -:';-';i'-" ,;,:-",-",-",y,-.; ~

,~

RI(ijHT POSTERIOR TEMPORAL --~------~

RI( HT MIDDLE TEMPORAL -----------+------ ------------- --------------------------4

RI( HT ANTER~R TEMPORAL -- - ----- -- --- -- ---

I

I LetT POSTERIOR TEMPORAL /" /--t- -·t'#-~----'---· .... ----- --+-----0---_-- --4f'--~~ --------..."

------------

Figure 22

Electromyograph record of subject number three showing the residual activity from. the anterior, middle, a.ni posterior fibers or the right and lett temporal muscles at mandibular rest atter the exercise of saying "Mia8issippi".

20 19 18 17 16 IS 14 13 12 rr 10

RIGHT POSTERIOR TEMPORAL

lWiI"'.~'~I:'~"~ ".I~ '.'<\. 1'~'I~ ... t~""'''I''ljij"~.,tlltll'''IMb~''4."'I.''I.''ib~''.~i.,, .. -

RIGHT MIDDLE TEMPORAL ... .............. ~... . '" ... ~~. . .......... ........................... --.... -~.,---....-......-............-..-.-.-.......... -------RIGHT ANTERIOR TEMPORAL

.. "f'"' ...... -~~-_ ......... t .... .-........-............... ~_--. ___ .......... _.~ __________ -+ ___ ..... __

LEFT POSTERIOR TEMPORAL

r_.~'ij.~.~'.~j.~fj.+",~"'~~~~~~~"'f ~.'I"._'~~ MlgDLE TEMPORAL

'" r ".,.1...J. 'r"~""'''''1.1it*~~~ '~""i ~.\\~

LEFT ANTERIOR TEMPORAL '."' ........ ,~~"~., "4-"~ .. "''' .... , .••• '''" ... ,~fil.'",.,.. ... ~'1o ... ''',,.. .. ~''I .. t.,'4I', .. .,.

AFTER SAtlNG'MISSISSIPPI'

naur. 22

Figure 23

Ilectr~ograph record of subject number three shoving the residual aotivity from the anterior, middle, and posterior fibers of the right and lett temporal muscles at mandibular rest after the exercise of swallowing.

40 39 38 .. " .... ; , , ""j"

RIGHT POSTERIOR TEMPORAL

RIGHT MIDDLE TEMPORAL

RIGHT ANTERIOR TEMPORAL .......... ....... -........... - ..,_ .. ~- .. - - --- -~ .... - ... - -- --

"'Ii' II" ...... 11... ...,.,. ... II ...... ', I .' " •• ' ".... "'~ '1"'" ' ..... _, • "to I I .. 4FTI:. SWALtow.. .

J'1i;uro 23

.Figure 24

Electromyograph record of subject number three showing the residual activity from the anterior, middle, and posterior fibers of the right .and left. terr.ryoral muscles at l'I1a.l1Qibular rest after the exercise of m8Kimal OPAning.

14 13 12 II fO 9

RIGHT POSTERIOR TEMPORAL

11'1M"".~."",,~~.,~I't~~'I""'~~~I\I~'II ••• '.ri~"~~',",II-'~I4I4~iM"'.''''til •••. RI GHT MIDDLE TEMPORAL

...-_ .... - ........... -_" t·· ~- .. _ .... _ ........ ,..... _, ____ .. ____ .4_· ___ .-___ -.-... _ .... _ . .......-._ •• ~ ........ -~. ---

RIGHT ANTERIOR TEMPORAL

I LEFT POSTERIOR TE~PORAL ~,J

.. t~~"~~~ft'ti ~.-.~I_t'.~~ .... ~~I".,~if~,'~.~"'~~~U.~,~~~ ---"1t+' .. _,_~_=, .. ~~~~.~~ojjj,--, ..... ,. ~

I

LEFT ANTERIOR TEMPORAL .J .......... , .... ,.... ............ ·.1&1.4.' ....... "'I"'", "'., ...... ~~'~~I'''.''I~ ... · •• ''''.if.,~~~i.~~I.-t ............. i Is~1 .... l

AfTER MAXIMAL OPENING

I

Alternate high and low voltage act1v1t;v in the middle and posterior fibers of the right temporal muscle from the subject number one.

-

S3

RIGHT POSTERIOR TEMPORAL

RIGHT MIDDLE TEMPORAL -- .. ...... • ... 1 ••

RIGHT ANTERIOR TEMPORAL

LEfT POSTERIOR TEMPORAL

LEn MIDDLE TEMPORAL

LEFT AtH ERIOR TEMPORAL 1-, ..... ~ .... -............. • .... , .- .... 11 .... -,- ......... - .-,.--..... ~ .. -.-...... _~ ....... ""'" ...

Illustration of the sensitivity of the .lectr~ograph equipment.. Note: A straight. line recorded by the crystograph pen up to the gai.n eight and pen defiect10n due to high cycle amplifier noise nt gain ten.

GAIN 9

GAIN 8

GAIN 7

GAIN 6-

GArN 5

·GAIN 4

GAIN 3

INPUT OJJv,

CHAPl'ER IV

DISClJSSICJI

The past llterature in physioloQ has shown that there is no actirlt7

in a relaxed. m.usole. Adrian and Bronk (1929), Smith (1934), Lindsley (193$),

Hoefer and Putnam (1939), and Weddell, '.inst.in and Pattle (1944) have

worked on yarious museles of the bod1, e.g., trioeps, bic.ps, deltoid,

braoh1o-radialis, rectus feaoria, vutus lateralis, sartorius, gUtrocna1U8,

tibialis anticus, and other tnmk, abdominal and neck lIUscles. Thq did not

record a:ny electrioal acti'Yity when these 1!"1soles were at rest.

~ the 0 ther hand, 80M investigators recorded 80me eleotrical poten­

tials trOll the postural DIlsoles at rest. Gilaon and H1lls (1941), losma

and Gellhorn (1946), Joseph, I1ghtingale and WUHa. (19$5), and others

ha.... studied the aoti vi ty of s ..... ral postural JIllseles at r.st and recorded

min'MaM activity. Since the.e antigrarlt7 1IlUseleS md.ntain the posture of

the bod,., they exert little more tension tban the other resting skeletal

DIIlScles. This activity is reterred to as "tonus" or "1IiD:1DIua muscular

acti vitT" •

(elton and Wr1aht (1949) also studied various postural muscles ot the

leg and mandible (masseter and anterior fibers ot the temporal _soles) and

found that the,. were electrically silent .. except tibialis anterior ~d

soleous IIlsCleS which shoved little activitYe Dental llterature also shows

s1JlUar results trOll the postural JllUc1es ot the undlb1e. Moyers (19SO),

MaoDougall and AndreW (19$3), Ballard (19$$), Latif (19$7), Javou (19$6),

Mullen (19$6), te.1e, Perr.r and c~ (19$8), .leuan (19$9), and Garn1ck

(19$9) studied the temporal IlUScles at rest. 'l'hq ell recorded the IId.n1JIum.

-.cular activit)" troll. this _sole.

'fbis stuq corroborates and elaborate. on the tadings ot Jarabale (19$1).

Ie recorded h1Peractivit)" tl'OJlt the temporal mscas at rest a edentuloue

subjects. He also •• ened tbat this acti'f'1ty deoreued. attar onset. LeIa1e j

Perry and CNa (19,8) recorded the 1I1n1DtwI .. alar actinty tro. temporal

llWIo1es at rest in edentulous subjects, but thtq' did. not .-ntion the nature

of this actiY1ty. Jeu. (19$9) ftOorded s1mUar 1I1n1aa _scular activity

troll. the temporal _soles which was c0D8tant.

In tl8 present studT residual aetiY1ty was reoorded from the temporal

_soles at mand.1bular reat in ed.entulou. subjects. The activity was found

to be decreasing tor abCllt twenty-tive seconds attar its ons.t. Jarabat

did not reoord a:n::r suoh acti'f'1ty in the control group ha'Ving Ml complements

ot natural teeth. The author did not have a control group because his

exper1ll8'1t was designed to studT the onset, JIlapltude, duration and trequenq

ot resldllal activity in edentulous subjects. (elton and Wright (1949) d:Ld.

not record any residual. activ1ty from the anterior fibers or the temporal

IIlUsoles, but they did. not state the dental conditions ot their subjeots nor

did the7 stat6 at what leYel of sens1t1v1tT their 1Detrwaent. recorded.

$1

lIo7ers (19SO), and KacDoupll and .Andrew (19SJ) recorded 1011· level

actin ty tra the tetapOral _8oles in normal 1nd1 vidllals which was conetant.

Javol. (19)6) and JlUJ.en (19)6), a1nta1ninl the head in a cephalostat,

I"Horded low level activity troa the temporal _soles. In our stud7 the

cephalGStat was not used to orient the head 'because the aubjects became

_1"8 apprehenaive and conscious ot the situation, cauina increase in

subjective variation. Ballard (1955) suggested that there DI&7 be a change

in the pattern ot actint7 it the 1nd1v1dual's head is olamped in a cephalo­

stat. .Jensen (19$9) tOlU'ld no slgn1t1cant difterenee between the results

obtained with the head and. ramdib1e in their natural position or when

oriented in a cephalostat. The u .. ot a llirror in our stucq (Fig. S) helped

maintain the natural post tion of the head, and orient it on tile Franktort

horisontal plane. Tb1s eli'linated the stretched position usuall.y &Ssociated

With bead t1:a.tion in the oephalostat.

Garn1ck (19$9) _semel a wide range tor the teaporal II\1soles during

which least aotin t7 W&8 recorded.. This range extends troa the vide open1n&

ot the lIOtlth to the li&ht ocolusal oontaot ot the teeth. When teeth caM to

11&ht occlusal oontaot, the tem:poralllUScles shawed lreater activit7. It

18 trae, &8 Sichel' 8qa, that the rest position ot the andible does not

depend on the pz"eseDle ot teeth, but it is likely that the presence ot teeth

and their periodontal 1Ie1Ibrances would establish a MJIOI7 pattern to guide

the JIaIld1'ble to reat position.. In edentulous individuals this --17 pattern

is distorted because propl"1oceptors from. the teeth are lost. Since the

guidance tro. the teeth is lost, these edentulous indiviCilals would have

S8

the tendency to overolose which causes oontractions of the tibers of the

temporal muscles. 'fbi. inoreases the tension 1n the lIUele proprloceptors

which send impulses at a reflex level. into the _sencephalic root to relax

the IIlsele tibera and thus re-establish the resting mandibular JIlUscle l8:llgth.

thus it would follow that activity in the temporal l'\lI1scle decreases

during this period. The postural position of the mandible is dete1'll'dned by

the proprioceptors wi thin DtU.Bcles and temporomandibular joint. This also

indicates that such residual activity is due to stim.uli originating trom the

peripheral nervous .,..te. and is at a retlax level.

Host of the subjects in this study showed residual activity arising

from the temporal IlUscles, similar to the fasciculations recorded by DeJl1'l7-

Brown and Pennybecker (1938) in patients ot progressive muscular atrophy.

ftiese tasCiClllationa are regular periodoic d1.scharges of single impul.see of

motor neurones. The disease usuaU7 attacks persons between the ages of

fOl'tT.tiyeand, :1It7 years, but it may also attack older parsons. Althou.gh

the residual activit7 seen in experiment conducted tor the present study baUl

reseMblance to that reported by Denny-Brown and Pennyt>ecker, the histories

given by subjects used in this experiment did not reveal other aymptoms

needed to contirm progressive lIlUBcular atrophy. Although some of these

subject. were senile and geriatric neurological and DlUscular changes have

S9

set in on a subclinioal. level, it is still conceivable in the light of

earlier 'Works (Jarabat, 19S1, Lenmde, Perry and Grunt, 19S8) this aotivity

is assoo:i.ated With the 108s of proprioception arising from the teeth rather

than from some neurologioal source.

Temporal muscles are the elevators of the mandible. One of their

functions is to 11lI.intain the mandibular posture at rest against the grmts.-

tional force. This devel.ops a certain amount or tension in the fibers of t

this muscle which 18 called "tonwa". The tonus of _eele ,is f~rl.y oor../Stant

so long as the muscle exists in a fairly constant environment, but it will

va.r:r slightly with a change in conditions, such as blood pressure (ris1n,

or tal.l1ng), bodJ metaboli_, mttr1tion, aging, acute or chronic llinesses,

etc.

Since all subjeots in this study were edentulou ard had dUf1culty in

chewing, and sinee they' all. were tbOVA the age of forty-, there w<*ld be some

change in mu.ole tone despite their seemingly sound p~8ica1 condition. But

there could not be alV' noticeable change in tonicity during the brief period

when these electrOflV'Ogl'aphic records were taken, thus indicating this

residual activity could not postdbly be dne to change in I81sole tonie1.ty.

Each exercise in this experimsnt was repeated ten times before the

mandible came to rest; this would invar1a.bly fatiaue the temporal muscles,

especially during the exercise of "max:1.mal opening" when MOst of the motor

un! ts were f'unetioning. Whenn-er a muscle is fatigued. 1 t undergoes

60

tascioulation which last. even attar the 1I1.00e relaxes. These fascioulatio%8

due to fatigue are small DurstS ot contraotions in a fasciaulu and are due

to irregular discharges of nerve. The discharges progressively spreu to

all nerve bundles in the fascioulaa. These fasciculation. lIt81 be tonic

spaSlIS wherein a muncle contracts tllOre or less energeticallY' without the

oonsoious intention ot the individual. The disturbance in thin1d.ng and

emotion, due to Tarioo.s reasons, may also oause the bJ'peractiv1ty of the

motor system through '-he wramidal oeUs ot the oortex; this would eau.e

the irregular muscle oontraction. It is dOttbttul, however, that t~ aotin t7

would bear likeness to the fasciculation. seen in these experiments.

Mullen (1956) showed that it the sensitivity ot the electromyograph b&

kept between the gain one to four, it w111 not aaplif7 the small action

potential ot nd..n1mua a.uscula.r activitY' large enough to be recorded. He

used the senaitiT1ty of p.1n ten because he could obtain the ma~1IUM pen

deflection tor the 1II1nilIwI _scular activity. Jawis (1956) and Jensen (19)9

also used the sensitiv1t.7 ot gain ten during their studies.

The elect~cgraph instrument used in the present stuqy was found

etticient at galn e1ght. When the eleotZ'OlllTograph and cl"1'8tograph were

switched on withou.t feeding arrT ourrent through the amplifiers, pens recorded

straight lines up to the gain eight after whioh, at gain niDa, these peu

became shdq' (ng. 26). At gain ten there was pen deflection e .... n though

no current was ted through the equipment. The baae line irregularity was

61

due to the high cycle noise output of the amplifiers. Thus, gain eight was

found efficient to record the 1Ilini.mum Jl'lWJC1Ilar activity and at the same time

to avoid recording amplifier noise.

Subjects used in th1s study were all between the ages ot forty and

seventy years ('fable I). The aTera,;. voltage output per second obtained.

from the temporal mu8cle& during rest in these subjects had no relation to

their age (Fig. lS). SUbjects ea- torty-tour, fony-nine and sixty-eight

years had greater ~rag. microvolt-seoond output than other subjects whose

ages were tifty-five, sixty-nine and seventy ,eus. Qle ot the specific

requirements in selecting the subjects for this stu~ was that they should

have had all their teeth extracted two months to a year prior to the testing.

Table I shows that there was no relation between the average voltage output

per second and the length of time these subjects were edentulous. This

leads to the inference that spontaneous h7Peractivity is alao in no way

related to the length of time the sUbjects were edentulous.

The anterior, middle and posterior fibers ot the temporal muscles were

studied to eValuate the function ot these fibers during mandibular rest in

edentulous subjects. This division was based. on the direction ot the various

muscle fibers.

'rhe analysis of variance has indicated a h.ighlT significant difference

between the voltage output of these groups &8 shown in Table I. Figure 13

demonstrated that the enerQ output Ql ring the residual activity of thes8

62

fibers was directly proportional to "their direction. The anterior fibers

were vertical in direction and had the least energy output during the

mandibular rest. The middle fibers (located posterior to the an"terior fibers)

became oblique in direction and yielded a greater energy output than the

anterior fibers. The posterior fibers had the greatest energy output during

rest, they took nearly a horizontal path from the origin to insertion.

This was in agreement with the findings of Latif (1951) who observed

that posterior fibers were more active than the anterior fibers du~ing

mandibular rest, and with Moyers (1949) who found s1m1la.r results in some

patients with mandibular retroversion. The greater energy output obtained

from the posterior fibers of the temporal 1IUsoles in this study also confirmed.

the clinical observation that the mandible is slightly retracted at rest in

edentulous patients.

'the residual activity at rest was recorded after performing three

different exercises, i.e., saying "Mississippi-, swallowing, and maximal

opening. These exercises were selected on the basis of their practical use;

since they are commonly used in establishlng rest position during the

construction of full denture prosthesis. This stuQr revealed that the energy

output during rest, after the exercise of saying "Mississippi", was little

less than after the exercise of swallowing and maximal opening (Fig. 1.3).

The anterior and middle fibers of the temporal MUscle showed more residual

activity during rest after the exereise of maximal opening than atter the

63

exercise of swallowing. The posterior fibers showed more residual acttvity

after the exercise of swallowing than a..fter the exercise of maximal

opening (Fig. 13).

An explanation would. be as follows: The first few swallowings are done

naturally without undue muscular stra.in, but additional swallowings become

an effort and must be forced. This causes the power muscles e.g., the

masseter muscles, to contract more vigorously while the mandible is being

elevated for swallowing, and it also retracts the mandible slightly. The

retraction, which causes more activity in the posterior fibers of the

temporal MUscles, does not happen during the repeated opening and closing

movements of the mandible, at this time only the elevator muscles are

functioning.

It is interesting to note that in thia experiment the left temporal

muscles showed more activity than the right in all subjects except one who

had more active right. temporal muscle than the left. In incliTiduals baving

full complements of natural teeth the temporal muscles of both sides usually

respond alike postural1y. In this study a significant clifference was found

between the energy output of right and 16ft temporal muscles (Table II). Thil

indicated that the mandible deviated from the midline of the body, causing

more activity in the temporal muscle of the side towards which it deviated.

It is difficult to attrib~te this mandibular deviation to ~ specific

factor. There are, however, several conditions which may have led to the

64

deviation: (1) dental aa.lolJclusion, (2) an accoDllleda.tive pattern of closure

into centric due to the loss of some teeth and the shirting of others,

(3) asymmetries in mandibular size, and (4) unilateral displaoeaents.

Since accurate histories of the original denture conditions were not

aya1lable, one can only speculate on the etiology underlying these lll.(mdibular

deviations. This experiment dOClllnSnts many more disturbances in the normal

opening and closing movements of the jaws than are described herein. It is

unlikely for one to associate the deviations with muscular memory patterns.

The automatic renexes, as automatic movements are known, were reflexes wh1ch

had to be reinforced for long periods ot time to make them 8ut0I1Voltia.

Assuming these reflexes were reinforced by the teeth, the reinforcement was

lost when the teeth wertl lost. The questi<m then is 1 It reinforcement

ceases, when is the automatic reflex behavior lost to the memory? This

experiment (that portion dealing with mandibular deviation) seems to indicat.e

that the renexes reuin tor some time because they se_ to receive some

reinforcement front the musole, tendon, and temporomandilmlar joint senso17

mechaniS1ll.S •

The energy output from the temporal muscle s during rest was not constant

throughout one minute recordings. It was found that the residual. activity

decreased in amplitude and frequency for about forty-five to fifty seconde

alter its onset and then it either remained the same or increased slightly.

These findings indicate that there is some tension developed in the musele

6$

and tendon proprioceptors due to altered position of the mandible during

rest. The muscle fibers make an effort towards reducing this tension and

thus decrease their activity lIJ' locating the true rest position of the

mandible. At no time did this residual activity cease completely, except

in one subject, in the anterior fibers of the left temporal muscle, it

ceased towards the end of a one minute period after the exercise of swallowing

In anoth.er subject this activity, in the posterior fibers of both sides,

quieted down in thtrty seconds after the exercise of swallowing. The resid:ul

activity was demonstrated immediately after the cessation of the exercise

without any-period of intervening relaxation.

Considerable variation was shown between subjects as illustrated in

Figure 15. An analysis of variance table (table II) also indicates highl,.

significant difference between the SUbjects. Many factors eould contribute

to this variation. The personal subjectivity contributed greatlY to the

variability, since no two indiviciuals were th.e same in personality or

behavior. The posture ot the head also had an influence on the activity of

the temporal muscle. Pruzansky (1955) and carter (1959) recorded low

amplitude activity from the temporal muscles when the head was rotated to

the right or left, while Nintaining it in the same horizontal plane. Jaralaak

(1957) noticed that a slight change in the position of the head would change

the activity of the temporal :muscles. Vano\1cek (1957) also has shown that

the minimttm muscular activity, associated with the postural position of the

66

mandible, was sometimes affeeted by head inolinations. Despite the fact that

the head position was oontrolled by the use of a mirror (Fig. 5), variation

may have resulted from faulty head orientation beoause of previous posture

habits. Although the physical oonditions of the subjects varied during the

different hours of the day, variation due to time was minimized as much as

possible by collecting records during the afternoon hours.

This experiment was designed to reveal the presence of interactions

between the main sources of variations. Tbree interactions were highly

significant as shown in Table II. The activity of the different muscle

fibers varied in all individuals, sinoe it depended on the subjects' ph7sioal

and physiological conditions at the time when the records were taken.

Similarly the activity of the temporal muscle of both sides was as,ymmetrloal.

This a8ynmetrr of the activity could be due to many factors mentioned

previously in this study. 'rhe patterns of speaking, swallowing, and opening

the mouth maximally varied in an individual and between the individuals.

The remaining interactions were not significant, and so were grouped as

"residue".

It was necessary to record the duplioate readings so as to measure the

reproductibUity of the activity of the indirldual.. In this experiment

two readings were selected at random from four or five oonsecutive recordings

of the activity of the temporal muscle~ ~t ~dibular rest. Tbe estimate of

error due to duplicate readings was identical. with the estimate of error due

67

to residue, and so the sum of the squares of these two errors were added

together to get the estimate of the total experimental error (Table II).

Thus it may be eoncluded that no findings oould attribute purely or eTen

remotely to the change in the museular activity in spite of the eonstantly

low values in amplitude.

OHAPTER V

SIMMARI J\lttD CONCLUSION

A crystograph was used in oonjunction with the electrom,ographic

equipment to study the res!dnal act! v1 ty in the temporal muscles during

mandibular rest in edentulous subjeots. This study included ten edentulous

subjects between the ",es of forty and seventy years, who had all their

teeth extracted two months to one year prior to the testing. The right

and left temporal muscles were studied in three parts; the anterior, middle

and posterior fibers. One m1nute rest activity was recorded after the

cessation of three selected exercises, i.e., saying ~s8i8Sippift, BWa1l~

and ma:d.al. opening. Each exel"01a8 was repeated ten times before br1n.ging

the mandible to rest.

The following conclusions were based on the qualitative and quantitative

analysis of the data collected.

1. The reaidnal activity;.waa recorded from the temporal muscles

d.urinl the lEnd.iluu!" rest in all subjects. One subject, however,

showed this activity only atter the exercise of maximal opening.

2. The onset of the residual activity was recorded immediately after

the cessation of exercises, without fillY period of complete inter­

vening relaxation, and it was continued for the entire one minute

period in most subjects. This residual activity decreased in

amplitude and frequency tor about forty-five se.onds after its onset.

68

69

3. The anterior fibers ot the temporal muscle were least active

while maintaining mandibular posture; the middle fibers were more

active than the anterior fibers; the posterior fibers were the

most active.

4. The residual activity obtained after the exercise of saying

ftMississippi" was least in amplitude and frequency; that after the

exercise ot swallowing was greater; and that atter the exercise or

maximal opening was greatest.

5. The lett temporal muscle showed more activity than the right

temporal musele in all subjects except one, who showed more

activity in the right temporal muscle.

6. The analysis of variance showed significant difference between the

subjects. There was no relationship between the age of the subjects

and the residual activity recorded tram their temporal muscles.

1. There was also no relationship between the length of time these

subjects were edentulous prior to their testing and their recorded

residual activitYe

CHlPTER VI

BIBLIOORAPHY

1. Adl."ian, B. D. and Bronk, D. W. 1929, The Discharge of Impulses in Motor Nerve roers J, The rrequencr of Dischari. in Rellex and. Vo1untal7 Contractiona. J. ~sio1. 61all9.

2. A.rId.ns, Herbert and Colton, RqIaond R. Colleie CUtl1ne Series, Table for Statisticians. B8l'Ils and Noble Ine. New York.

3. Ballard, C. F. 19,$, A Consideration or the ~8iologic Baokground of Mandibular Posture and Movement. Dent. Pract. 6180, Jfovember.

4. Bosma, J. F. and Gellhora, I. 1946, llectl"OlQ'ographic Studies ot Muscular Coordination on St1lllu.lation of Motor Col"'tft. J. 1!'!!R!q;siol. 9.263.

,. Carter, omert Vincent. 19,9, llec~araph1c stuq ot Mandibular Posture as Influenced bY' Horizontal Changes ot Head Posture. Thesis, Loyola Univenity Sohool ot Dentistry, Chicago.

6. Denny-Brown, D. and Pennybecker, J. B. 1938, fibrU1ation and Fasciculation in Voluntary Muscle. Brain. 61.311.

1. Garnick, Jerrt'o 19$9, llectrOllVographic and Clinical Study ot the Rest Position ot the Mandible. '!'hesis, University of lf1.ohigan, M1chigan

8. GUson, A. S. and HUls, W. B. 19b1, .Activities ot Single Hotor Units in Man During Slight Voluntary Efforts. Am. J. P&sio1. 133 :6,8.

9. Boefer, P. r. A. and Putnam, T. J. 1939, Action Potentials ot Muscles in Iformal Subjects. Arch. Ifeuro. and PV9h• b2. 201.

10. ------------------- 1940, Action Potentiala ot Muscles in "Spastic" Conditions. Arch. 1eur"Gl. and P!l~ 43,1.

11. ------------... ------ 1940, Action Potentials of Muscles in Rigid! ty and TNllors. Arch. Neurol. and PSZch. 4) 1104.

12. lO81'er, P. P. A. 191U., Innervation and Tonus ot striated Muscle in Man. Arch. Neural. and Puch. 46:941.

10

71

1.3. Jarabak, Joseph R. 1957, An ElectroBtVographic Analysis ot Muscular Behavior in Mandibular Movements trom Rest Position. J. Prosth. 7:682.

14. ------------------ 1960, Personal Communication.

1S. Javois, A. J. 1956, An ElectrOJlTographic and Cephalometric Radiographic Studf of Reat Po.ition ot the Mandible and the Interoccluaal Olearance. Thesis, Northwestern Univeraity Dental School, Chicago.

16. Jensen, James Lee. 1959, An ElectrOlViYOiraphic Stud;y of 'ace Height in Complete Artificial Denture Subjects. 'fheaia, .orthwe.tern University ~tal School, Ohicaio.

17. Joseph, J. Ni,ht1Dgale, A. and. WUliau, P. L. 19.$5, net.a1led stu~ of the Electric Potentials Recorded over S.. Postural Musl1l.es while Relaxed and Standing. J. !:!lai01. 127 t611.

18. Kelton, Jan li. and Wright, DOUglas R. 1949, The .Mechanism of EU7 Standing b7 Han. Australian J. of E!:pt. 1101. and Med. Science. 27.$0). .

19. Irol, Arthur J. 1960, Personal COlJJIII.U'lication.

20. Latif, A. 19.$1, An Electrom.rographic Stud;y ot the Tsmporal Musole in lorma! Persons daring Selected Positions and Movements of the Mandible. Am. J. Ortho. 1&3 • .$77 •

21. Lemati.e, G. A., Perr,y, H. T. and Cl"'WIIIl, I. D. 1958, Certain <l>servat1ons on Complete Denture Patients. Part Is Method and llesults. J. Prosth. Dent. Yol. 6, no. ):186.

22. ----••• _------------------------------------ 19$8, Certain Observations on Complete Denture Patients. Part ns neotrom;yographic Observations. J. Prosth. Dent. vol. 8, no. 6:929.

2.3. -----------------------... ---., •• - 19$9, Certain ~servations on Caplet. Denture P diients. Part In c Consideration of the Results .t'rOJll a. ReurOllDlSaular Viewpoint. J. Presth.. Dent. 9:.34.

II

24. Lindsley, D. B. 19.3$, &lectrical Aativ1t7 or Human Motor Units during Voluntary Contractions. ~. J. nP'aiol. lllu90.

250 MacDougall, J. Do B. and Andrew" BoO L.. 1953" An Electromyographic Study" of the 'l'emporalis and Masseter Mnsc1es. J. of Anatomy .. 87:37.

26. M&r1nolli, A. A. 195" Clinical El.ectrom;rograpb;y. San Lucas, Los Angeles.

72

21. Moyers, R. E. 1949, Teaporomandibular Iilsole Contraction Patterns in .IDgl. Clu8 II Di'ri8ion I Malocclusion) .An ElectrolQ'ographic .A.naJ.rsia. All. J. Mho. 3S.837.

28. Moyers, I. I. 1950, An n.ctroJlTOgraphic Analysis of Certain "olea Involved. in Teaporoaand1bular JIoyeMnts. Am. J. Ortho. 361481.

29. -------.-.-- 19$6, Soa. PhJaiologic Considerations of Centrio and Oliher Jaw Relations. J. Proeth. Dent. 61183.

30. Mullen, R. P. 19>6, .An Electromyograpbio Investigation of Postural Position of the Mandible. Thesis, Northweatem University Dental Sohool, Chicago.

31. Per!7, H. T. 19>4. An Eleotromyographic Study" of the Temporal and Masseter boles of Individuals with Excellent Occlusion and Class II Division I Malocclusion. Theais, Northwestern University Dental School, Chic ••

32. Pruzansky', Samuel. 19,5, The Control of the Posture of the Mandible during Rotation of the Head. J. D. Res. 35:720.

33. Ralston, H. J. 1953, The Question of Tonus in Skeletal. Muscle. Am. J. PblB. Med. 32:8,.

34. Sherrington, c. S. 191" Postural Activity of Muscle and Nerve. Brain, 38 :191.

35. Sioher, H. 1949, Oral AnatOll7, c. V. Mosby Co., St. Louis, Mo.

36. ---------- 19>4, Positions and MOvements of the Mandible. J. Am. Dent. Asaociation, 48.620.

37. Smith, O. C. 1934, Action Potentials from Single Motor Units in Voluntary Contractions. J. Phzslol. 108.629.

38. Snedecor, G. W. 19,7, statistical Methods. ,the ed. Iowa State College Press, Ames, Iowa.

73

39. travis, L. E. and L1nsd.l.q, D. B. 1931, the !elation ot FrequenCY' and Extent ot Aotion Current to IntensitY' ot HJ.scular Contraotion. J. Elg>t. Pbniol. llu3S9.

hOe Vanou.oek, H. T. Jr. 19$7, An Electrorqographic and Cephalometric Radiographic Investigation ot Variations in Mandibular Position in Relation to Head. Position. Illesi., Northwestern UniversitY' Dental School, Chicago.

lal. Weddell, G., Feinstein, B. and Pattle, R. E. 1944, The Eleotrical Activity ot Voluntar,y Mascle in Man Under Normal and Pathological Conditions. Bra1n1 67:178.

TABLE I

lfuDiJeF Rarne of Subjoats Age 1n Edentulous * A.VeFaa. Years in aonths Microvolt-second**

1. Lewandowski, Jose?h 44 2 1)8.1684

2. Fletc!ler, James 42 2 11.402$

3. Pippenger, Guy 68 S 391.2049

4. WalteF, Jur1s S2 3 66.9124

s. Crump, Jim 6$ 9 61.422$

6. nuk, stanley 41 2 ~.2hOO

7. Magiera, Thomes 10 12 59.S984

8. Martie, Joe 49 12 123.8769

9. H1tchell, Josepa SS U 7.4$29

10. Philips, Jack 69 8 37.3321

* A.pproximate time in months wring Which the patient was edentulous,

i.e., from the day last tooth was extracted to the recording was made.

** Aver&ie energy output per second by all MUscle groups.

74

fABLE II

. Sources of Degree of Sum ot Mean Variance Variation Fre.dom Squares Squares Ratio

Subjects , 26,86,.4606 2, 98S.oSll 391.3897***

Muscle Groups 2 22,332.6260 11,166.31)0 29.9887 ......

Sides 1 2,989.7868 2,989.7868 7.1221*

Activity 2 3 Sl.l444 17,.,122 1

Periods 3 90.)898 30.1299 309,**

Su. x Gr. Inter. 18 6,702.3141 372.3)07 48.8213***

SUo x Sides Int.er. 9 3,102.3141 419.7866 S'.0409***

Suo x Act. Inter. 18 4,3$0.6447 2hl.7024 31.6911***

Error 1,377 1O,)02.1)OS 7.6268

fotal 1,439 78,S35.1616 ,

7;

APPROVAL SHEEr

The thesis submitted by Dr. Naishadh Parikh has been read and.

approved bjr four members ot the Departments ot Anatomy and Oral AnatOlDJ.

The tinal copies have been examined by the director of the thesis

and the signature which appears belOW' verities the fact that my necessary

changes have been incorporated, and that the thesiS is now given f1nal

approval with reference to content, form, and mechanical accuracy.

The thesiS is therefore accepted in partial :tul..ril.l.ment of the

requirements for the Degree of Master or Science.