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Integrated actions of the four heads of quadriceps femorisAn electromyographic study.

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Integrated Actions of the Four Heads of Quadriceps
Femoris : An Electromyographic Study
J. V. BASMAJIAN, T. P. HARDEN AND E. M. REGENOS
Department of Anatomy and Regional Rehabilitation,
Research and Training Center, Emory University,
Atlaiztu, Georgia
ABSTRACT
From intramuscular bipolar fine-wire electrodes in the four heads
of quadriceps femoris, electromyographic recordings were made (along with electrogoniometric records) in nine normal men and women during selected postures
and movements of the loaded and unloaded knee. Variation between the onset
and cessation of activity between the four heads and from subject to subject was
found, but the vastus medialis reflected the general pattern of activity rather than
acting only terminally during extension. Rectus femoris had the shortest span of
activity during extension of the knee.
channels were recording on FM tape along
with simultaneous signals from an electrogoniometer recorded on a fifth channel of
a Hewlett-Packard multichannel recorder.
Subjects performed a variety of movements in a formal series of postures. For
the purpose of this paper, only the following were analyzed: (1) with the subject
seated and the leg hanging over the end
of the examining table, extension to 180"
and flexion back to 90" with - ( a ) gravity
only, and (b) an added 30 pounds (13.6
kg) load at the ankle; and (2) starting
with the subject standing upright, squatting to a position where the knees were
flexed to go", and then returning to the
erect position.
Analysis of paper print-outs from the
magnetic tapes consisted of two parts:
1. Timing of onset and cessation.
Each recording was analyzed in relation
to the angle of the knee at which activity
began and ended in each head. These results were tabulated for the nine subjects,
providing means and standard deviations
for the pooled data.
11. Grading of activity. Using the goMATERIAL AND METHODS
niometer record, individual EMG chanNine young, healthy adults (6 men; 3 nels were evaluated in epochs of time durwomen) acted as subjects. Bipolar fine- ing each movement on a scale of activity
wire electrodes (Basmajian and Stecko, thus: no activity is 0; slight, 1; moderate,
'62) injected in the middle of the belly of 2; marked, 3; and very marked, 4. Results
each head of quadriceps, provided excellent were compiled in tables with means and
electromyographic response with no "crosstalk,"' Greatly amplified, the four EMG
Received April 8, '71. Accepted July 22, '71.
Why are there four heads for a muscle
that has most of its insertion on the restricted edges of the patella? Do the various parts have individual functions? Although Lieb and Perry ('68) answered this
question in part by ingenious morphological and biomechanical studies of amputated limbs, electromyography offers an
added dimension to their findings by revealing the actual timing of activity and
the interplay of function in the four parts.
Earlier electromyographic studies by Pocock ('63) and Close ('64), limited by
technique, offer provocative but useful
ideas that require confirmation, expansion,
and quantification. An incentive for gaining new and precise information arises
from the growing interest in myoelectric
assistive devices for the physically handicapped (including programmed muscle
stimulators for recruiting of lower limb
muscles in proper sequence). For these
reasons a detailed study was undertaken
of the interplay of activity in the three
vasti and the rectus femoris in a group
of normal adults.
ANAT. REc., 172: 15-20.
15
16
J. V. BASMAJIAN, T. P. HARDEN AND E. M, REGENOS
standard deviations, the latter figures giving some indication of the range of responses in this rather short series of subjects.
but is not greatly different from the other
heads during the act of squatting.
DISCUSSION
I t is now becoming widely recognized
that vastus medialis acts through the
I. Timing of onset and cessation. w-hole range of extension, not just a t its
Figures 1, 2 and 3 summarize the tabu- terminal phase (DePalma, '54; Lieb and
lated results of the pooled data. I n sum- Perry, '68; Basmajian, '70). Also it is in
mary, the most striking features are: ( a ) this terminal phase that the muscle is supthe variation between the different heads; posedly the most active because it com( b ) the considerable standard deviation pletes extension. However, another very
arising from individual differences; and real function of vastus medialis at the end
( c ) the late onset and early cessation of of extension is its prevention of lateral disactivity in rectus femoris during the squat- location of the patella, The special directing manoeuvre.
II. Grading of activity. Figure 4 sum- tion and insertion of the lowest fibers of
marizes the findings. The most revealing the muscle point directly a t this being the
findings are the similarities between mus- real role of that lowest part of the muscle
cles in the pooled data with the consider- which bulges so prominently here.
Most clinicians and functional anatoable variation in individuals at certain
times (the most marked variation occur- mists believe that a n unstable knee is due
ring at the end of straightening up from to a n inability to produce the final 15" of
the squatting posture). There is no ques- extension. I n turn, many clinicians contion that weighted extension recruits the tinue to believe that this failure is prigreatest activity. Vastus medialis does ap- marily due to weakness of the medial head
pear to increase its activity more rapidly of the quadriceps. It is difficult to deny
toward the end of unweighted extension that the final 15" of extension is imporRESULTS
Fig. 1 Diagrammatic representation of onset and cessation of activity in the four heads
of quadriceps during unweighted extension of the knee from 90" to 180" and flexon back
to 90".Subject seated; no added load. Mean and standard deviation of the angle at which
activity begins starts each line; the broken arrows indicate the direction of movement to
full extension and back to the mean and standard deviation of the angle at which the
activity ceases.
17
EMG OF QUADRlCEPS
*.d
VASP.5
I
go
-*------+----+--I
-+------+-->
t - 1
UTEPXI 5
1
I
I
I
I
I
I
1
im
LU)
m
iul
ila
m,
1m
m
1
1m
Fig. 2 Diagrammatic representation of onset and cessation of activity in the four heads
of quadriceps during weighted extension of the knee from 90" to 180" and flexion back to
90".Subject seated; 30 pounds (13.6 k g ) added load. Mean and standard deviation of the
angle at which activity begins starts each line; the broken arrows indicate the direction of
movement to full extension and back to the mean and standard deviation of the angle
at which the activity ceases.
VMlU
EDIKIS
VA%%
LPlEwILIS
I
I
I
I
1
1
I
I
1
I
i m u o m m i a m m u n m r )
Fig. 3 Diagrammatic representation of onset and cessation of activity in the four heads of
quadriceps during squatting to 90" from the fully erect posture and back up again. Subject
standing; no added load. Mean and standard deviation of the angle at which activity
begins starts each line; the broken arrows indicate the direction of movement to 90" flexion
(squatting) and back to the mean and standard deviation of the angle at which the activity
ceases.
18
J. V. BASMAJIAN, T. P. HARDEN A N D E. M. REGENOS
U Y I \ t I G HT t D
-c
VASTUS
INTtRMEOlUS
f Y Tt h.r 5 I O N
4
WE I CHTt 0
STANOING
4
4
f 3
3
3
2
2
2
I 1
I
I
-
E X T E NS I ON
h
U
0
Oeqrees
W
I20 150
180
1% 120 W
0
180 1% 120
W
I20 I%
180
W 120 1%
180
W
I20 I50
IRO
90 120 150
180 I50 120 W
1% 120 W
4
1
2
FEMORIS
2
I
0
Oeqrrer 90
-
-
120 I50
180
I50 I20 W
A
180 I50 I20
4
A
c
VASTUS
LATtRALIS
-r
-"I
Q
3
3
3
2
2
2
1
I
I
0
0
0
no
w 1211 ISO 180 150 120 90
Fig. 4 Composite diagram of changing EMG activity rated zero to four during the movements of the knee reflecting mean and standard deviations at epochs of the movements
shown on the horizontal axis. Heavy lines indicate the means; shaded areas the standard
deviations.
Degrees
si~
1211 1%
im
150 120
w
180
tant. Indeed, the aim of quadriceps retraining is to enable a patient to extend his
knee fully and to maintain that extension.
Whether the fundamental part is vastus
medialis itself is open to serious doubt.
Lieb and Perry ('68) on the basis of their
most thoughtful anatomic study with
novel techniques, concluded that early
atrophy of the vastus medialis prominence coupled with the loss of terminal extension i s simply indicative of a general
150 120
90
120 is0
quadriceps weakness. Earlier Hall6n and
Lindahl ('67) reported essentially the
same findings electromyographically as
Lieb and Perry ('68) did mechanically.
Both groups established the general role
of vastus medialis rather than its widely
touted terminalextensor function. HallCn
and Lindahl ('67) also stressed the importance of pain inhibition and adhesions
in the limitation of extension in its
last 10".
EMG OF QUADRICEPS
19
The visible prominence of the vastus appear to be especially fallible where the
medialis is really related to the marked quadriceps femoris is concerned.
obliquity of the distal fibers of the muscle,
Pococks fmding that quadriceps activits lowness of insertion and the thinness ity is less during the down phase of squatof the fascia1 covering in that area. The ting is contradicted by our findings which
extensor lag accompanying knee extension show a parallism between the up and
is a function of great loss in the mechani- down stages. Some difference in technique
cal advantage of the whole muscle during may account for his conclusion.
the final 15" of the extensor range because
A n important additional fmding in the
a 60% increase of force is needed to com- present study is the variation from subplete extension (Lieb and Perry, '68). ject to subject. This is particularly marked
Thus, the only selective function attribut- a t the conclusion of standing up from the
able to vastus medialis is patellar align- squatting exercise. Individual variations
ment. We cannot deny the importance of in responses of muscles must be taken into
the latter but it has no special part to play account in the design of myoelectric
as a prime mover in the final extensor devices.
movement insofar as mechanical advantage is concerned; this appears to be conACKNOWLEDGMENTS
firmed by our findings. A surprising burst
This study was supported by S.R.S. grant
of activity during squatting as subjects 16-P-56808/4-07,
pass from 150" to 135" remains unexWe wish also to thank our subjects and
plained.
Mrs. M. J. Shine, Mrs. G. Super, and Miss
The present study supplements those J. Gore for valuable technical assistance.
of Pocock ('63) and Close ('64) and offers
for the first time quantification in all four
LITERATURE CITED
heads (including vastus intermedius). Basmajian, J. V. 1970 Re-education of vastus
True, this does not greatly alter our undermedialis. a misconception. Arch. Phys. Med.,
51: 245-247.
standing of the vastus intermedius which
seems to have no discrete role. The ques- Basmaiian.. 6- . V., and G. Stecko 1962 A new
bipolar electrode for electromyography. J. Appl.
tion of "Why four heads?" is still unanPhysiol., 17: 849.
swered except in a negative way: the mus- Close, J . R. 1964
Motor Function in the
cles act in concert to achieve a common
Lower Extremity: Analysis by Electronic Instrumentation. Charles C Thomas, Springfield,
end. Minor differences (such as the burst
Illinois, pp. 130-132.
of activity in vastus medialis during squatL. G., and 0. Lindahl 1967 Muscle
ting) may alone explain the structural dis- Hallen,
function in knee extension: An EMG study.
creteness. The relatively short period of
Acta Orthop. Scand., 38: 434-444.
significant grades of activity in the rectus Lieb, F. J., and J. Perry 1968 Quadriceps function: an anatomical and mechanical study
femoris (compared with the vasti), also
using amputated limbs. J. Bone & Joint Surg.,
noted by Pocock, may also have some im50A: 1535-1538.
portance which is not now apparent. Any Pocock,
G. S. 1963 Electromyographic study
judgments of the timing of the muscles
of the quadriceps during resistive exercises.
based upon biomechanical probabilities
J. Amer. Phys. Ther. Assoc., 43: 4 2 7 4 3 4 .
I
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