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Muscle fibers of the tongue functional in constant production.

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MUSCLE FIBERS O F T H E TONGUE FUNCTIONAL
I N CONSTANT PRODUCTION
LEON H. STRONG
Department of Anatomy, The Chicago Medical School
Chicago 12, Illinois
T E N FIGURES
INTRODUCTION
The published descriptions and illustrations of the musculature of the human tongue lack accuracy and completeness.
Indeed, as pointed out by Abd-el-malek ('39), a detailed
description of the architecture of the tongue is not available
in the literature. His statement is still true, today.
The function of the specific tongue musculature in speech has
not engaged the attention of either anatomists or phoneticians,
except in a general way. Previous investigators have directed
their attention almost entirely to the configuration of the
resonating chamber in the production of vowels.
Since R. J. Rousselot's (1899) studies in palatography
which culminated in his critical analysis ('10) of former
palatographic attempts, accurate palatograms made with a
pseudopalate of the palatodental consonants have been available. Strong and Gold ( 'SO), approaching their work through
a study of force vectors of the tongue muscle bundles, suggested that certain bundles of the intrinsic musculature had
an architecture which would deform the tongue to conform
t o the outlines of palatograms. The present study is an
extension of that work.
To make preparations of the human tongue which when
photographed would show bundles of muscle fibers in entirety,
and thereby point out definitely the vectors of such bundles,
was the objective of our dissections.
61
62
LEON H. STRONG
METHOD
Frontal, transverse, and longitudinal sections were cut,
mostly 0.5 ern in thickness. Each section was then dissected
in 95% ethyl alcohol, under a binocular stereomicroscope.
Because of the interlacement of muscle fibers which as
shown by Dabelow ( '51) pass through an aponeurotic lattice,
it is very difficult t o dissect them out satisfactorily. This
difficulty is further increased by the fact that these fibers have,
intimately associated with them, nerves and vessels of greater
caliber than that of a high proportion of the muscle fasciculi.
To make the work less arduous, we have made most of our
dissections on fetal material or on infants. Pons-Tortella
('36) has shown that all the muscle systems of the human
tongue are identifiable by the third fetal month. Our dissections have shown that in the 44 month fetus, all the fiber
bundles have essentially the same relations as in the adult.
We are deeply indebted to Dr. John H. Mnyslrens, director of the
Laboratory of Eiolinguistics a t the University of Nichigan, for detailing one of his graduate students, Dr. Elizabeth Puglisi, to make a
special set of palatograms for this study. To her, as well, we hereby
render our sincere appreciation. Dr. Harold Fish kindly furnished the
material for figure 7. For the superb photography we wish to thank
Mr. Thomas Scanlan.
OBSERVATIONS
When all the different configurations of the palatograms
are massed together, the total area of the palate contacted by
the tongue appears as a peripherally placed horseshoe-shaped
figure. The legs of this horseshoe contact the three molar teeth posteriorly.
They extend to the incisocanine region
anteriorly. There an arch of contact
completes the horseshoe across the
midline behind the incisor teeth and
against them (fig. 1). The width of
Fig. 1 Generalized palatogram
by combinillg
the leg of the horseshoe cover somet h e 60 palatograms.
what more than the lateral third of
MUSCLE F I B E R S O F THE T O N G U E
63
the tongue. The arch is roughly the width of a leg. The
gradation between the palatograms of certain consonants is
small and some overlap. To bring out the relative movement
of the horseshoe on the palate, we have placed the palatograms
into 7 purely artificial categories of 4 palatograms each. They
have been arranged to bring out the maximum o r minimum
contact between the tongue and the palate with its contiguous
teeth. They show as well the specific form of the different
types of contact which produce consonants.
It should be born in mind that each individual's series of
tongue contacts is unique. However, in different persons, for
any specific contact, there is a high degree of similarity of
pattern, as indicated by Grutzner (1879), Gutzmann ( 'lo),
Luciani ( '15), Shohara and Hanson ( '41), and Rousselot
( '10).
With the exception of two categories, the central one-third
of the tongue's dorsum does not contact the palate and teeth.
Even in those two exceptions, the contact is immediately behind the incisor teeth only. There is present, therefore, a port
for exhalation of the pneumatic blast which escapes either
(1)in the center of the mouth, or (2) lateral and posterior to
the incisor region, but anterior to the molars. The latter is
illustrated in the enunciation of the 'L' of the word doll
(category 7 ) figure 3.
Palatograms of some 60 palatodental contacts used in
English have been examined. Since only a minor more medial
difference in contact appears when made preceding a vowel
than when the consonant follows one, the essentially different
contacts may be reduced to 30. Whether the carrying vowel
is AH (phonetic a ) or EE (phonetic i) determines the relative
mediality of the contact. EE gives the more medial impression. The peripheral contact is the same with either AH or
EE. The palatograms used are for the following consonants :
d, dzh, g, j, k, kw, 1, n, ng, r, s, sh, t, tw, z, ah. The categories
of these are given below.
64
LEON H. STRONG
Categories :
1. Contact in all is parallel to dental arch, complete.
COT, CZAR, TEa, J o h n
2. Same as in No. 1, but posterior contact increases
medially .
nEED, TWEEdle, kNee, Lee
3. Contacts parallel to dental arch from incisors to molars.
Breath port present.
ARe, XOb, cOfltunae, dODGe
4. Contact : from canines or incisors t o last molar; medial
margins parallel.
ZEbra, JAneiro, bugGI', REgard
,5. Same as No. 4, but medial margins bowed medially.
lEAXH, EGypt, QUEEn, L E d G u e
6. Contact contiguous with molars and incisors only.
10CK, COG, G o t
7. Contact with molars and incisors only; three point.
(10JlL
Fig. 2
Categories 1, 2, 3.
MUSCLE FIBERS O F THE TONGUE
65
It is apparent from inspection of these palatograms that
the tongue-palate-teeth patterns are the results of a series
of mediolateral changing contacts. One sees from them that
to pass from one consonant to another there is mostly a
medial movement of the area already contacted, or vice
versa. This involves a gradual increment of medial (or of
central, at tip) pressure of the tongue against the teeth and
palate. If I pass from COT to T E a (category l), I increase
contact of a particular shape all around the dental arch.
If I change then to J o h n from TEa the contact moves still
farther inward all around the periphery of the tongue. If I
then change to L E E (category a ) , the posterior contact moves
still farther inward, but the anterior contact moves outward.
Should I enunciate 1EAGue (category 5 ) after LEE the
anterior arch drops out completely.
Pig. 2
Categories 4, 5 , 6, 7.
66
LEON H. STRONG
Search f o r muscle bundles which could thus deform the
dorsum of the tongue in order to elevate and stiffen specific
parts of it so as to produce the palatal contacts illustrated,
has disclosed fibers the vectors of which could do so. Three
consecutive froiital sections of the tongue show the typical
arrangement and extent of these fibers (figs. 8, 9, 10). The
following sets of muscle bundles in vector combinations can
thus alter the dorsum of the tongue, as suggested by Strong
and Gold ( 5 0 ) . One set consists of those verticales which
pass from the dorsum to the lateral margin only. A second
set consists of those transversales bundles which extend
dorsolaterally only from the septum to the dorsum of the
tongue. The third set of bundles is the short bow system of
inbricated longitudinalis superior, attached to the dorsum of
the tongue only, A stereogram based on our dissections will
make these different vectors clear (fig. 4) as follows. The
stereogram omits the longitudinal system for clarity.
Two vector sheets of diagonal fibers of the transversus
system attached to the septum are shown limiting a given
area on the dorsum. Their tension (the vector of which
is ventromedial) , is emphasized by their thickened borders.
Between them at the dorsum are two sheets of verticales
whose thickened borders show them to be contracted. These
latter are rendered horizontal by the excessive vector applied by the diagonal (transversus) fibers to their medial
ends. The contraction of these verticales produces a ridge
on the dorsum of the tongue (fig. 5). The subaponeurotic short
imbricated bows of the longitudinalis superior, described by
Sommering (1841), serve to increase the stability of this
ridge. Dabelow ( ’51) remarks upon the “astounding transformability of the upper lingual surface” as a function of
the fiber arrangement. It is in no way the intent of this
paper to assign to the fibers emphasized an exclusive role
in the production of consonants, but to point out a complex
of bundles responsible for the principal deformation of the
tongue in the formation of certain consonants. By specific
innervation of such muscle fiber systems, all, or any part.
67
MUSCLE F I R E R S O F THE TONGUE
or parts of the n-hole potential horseshoe may be brought out
on the dorsal surface of the tongue as a hardened mass.
Thus formed, its configuration will print its impression on
the palate and teeth. It, is such a contact, which when broken
2’1g. 4 Stereogi:uii. Heavy liiics show contracted bundles.
of muscle bundle sheet is figured.
Fig. 3
Cut edge, only,
1)ors:rl apoiiciwosis of tongue showing peripberal horseshoe.
by an air blast, results in the emission of a sound which we
call a consonant. So far we have limited our discussion to
the legs of the horseshoe.
Our preparations shorn that in the tip of the tongue, in
addition to the fibers previously mentioned, a unique ar-
68
LEON H. STRONG
rangement of fibers exists, just back of the most anterior
verticales, but in front of the termination of the septum.
These we place with the transversus system. Such fibers are
attached to the aponeurosis near the juncture of the lateral and
middle dorsal thirds of the half tongue, pass through the
mid-region of the tongue and attach to tlie opposite lateral
inferior surface near the juncture of its middle and lateral
thirds. Thus, they decussate through the midline (figs. 6, 7).
The contraction of these fibers would cause the tip and the
region immediately back of it to rise into an oval shaped
eminence. They, therefore, serve as an arch connecting the
two legs of tlie horseshoe and, in addition aid in deforming
the tip so as to induce specific increments of pressure during
palatal contact. This configuration is nowhere described or
figured in the literature. The relative size of the tongue,
teeth, and palate, mould likewise play a part.
DISCUSSION
Seither tlie anatomist nor the physiologist has contributed
much to our knowledge of the function of the specific muscles
in speech production. Linguists and phoneticians have busied
themselves with one phase of speech, that of showing the
configuration of the boundaries of the cavity of the buccopharynx in the production of a resonating chamber for tlic
different ~ o w d s . TYliat they have failed to do is to show
which specific muscles are responsible for these configurations.
The configuration for any vowel has been corroborated by
radiographs. From these they have adduced the general
vectors of muscle systems of the pharynx and of the tongue
responsible for specific cavity formation. It is interesting that
Blandin (1823), in the first comprehensive and, considering
the time in which he worked, precise and adequate description
of the musculature of the tongue, did not include the topic
of speech in his paragraph on function. a f t e r a century and
a quarter of investigation on the tongue one gleans from the
literature little more functionally precise information than
Blandin gives.
MUSCLE FIBERS OF T H E TONGUE
69
I n the literature of the tongue, many conflicting statements
occur about the extent and position of the muscle bundles,
especially the intrinsics. Sommering (1841), working with
fresh human tongues denies the existence of any intrinsic
verticales, which he says Gerdy, Cruveilhier and others assume. Cruveilhier (1844) prepared sections showing them.
They were illustrated by Salter (1852) and called intrinsic
perpendiculars. Hesse (1875) established their presence by
convincing serial sections, and by a superb photograph of a
gross sagittal section, the first in the literature. His preparations were so excellent that Spalteholz (1896) made use of
them in his Handatlas ; they are retained in the Spanner Edition (’53), and to date, remain the most accurate illustrations
we have exa’mined. Poirier and Cliarpy (’01) categorically
deny their existence. Rouviere (’43) does not even mention
them.
Gray’s (’54) figure 1061, page 1262, a modification of
Krause ’s transverse section, well illustrates the verticales
but there is no leader to them. This emphasizes his statement
that they are “found only at the borders of the forepart of
the tongue,” page 1264. See our figures 8, 9, 10.
For an accurate illustration of the transversus bundles as
well as the verticales, one goes back to Krause (1879). There
only line drawings appear. Krause ’s so called ‘longitudinal
vertical’ section has long appeared in Cunningham’s Textbook, but Krause distinctly directed that the cut was not
longitudinal vertical. The 1951 edition retains this error.
When first we pursued this study, we tried, following Cunningham’s explanation of the figure, to imitate that section,
by section and by dissection, but our preparations did not
agree with the illustration. Then we went back to Krause’s
original paper where we learned the proper orientation. I n
the Gray 1954 modification of Krause ’s transverse section
(of the same paper) fibers transversely placed above the
septum run a course laterally, then turn in to arch inferomedially, and end very close to (or at) the fascia (aponeurosis). Such fibers occur in no other figure or description
70
LEON H. STRONG
in the literature, and in the Gray text no fibers conform to
them in the description. Diagonal fibers from septum to
dorsum are altogether missing. These bundles, which spring
from the upper half of the septum as f a r as its upper border,
and insert along the lateral third of the dorsum upon the
aponeurosis, we regard as one of the two prime muscular
mechanisms for the production of the palatodental consonants.
These bundles were first adequately described and figured
by Hesse (1875), although Salter (1852) had previously illustrated them in part.
I n vowel production, a different configuration of the resonating chamber appears for each vowel. The extrinsic
muscles are mostly involved. This resonating chamber for
the vowels became such a focus of attention to previous
investigators that the muscles which produce it were invoked
as functional, in con,starzt production. Braus ('24), in his
chapter on the tongue does not even mention the function
of speech. His discussion of speech production is under the
chapter on the pharynx (the vowel resonator). Barth's ( '11)
figures which Braus modifies are all midline views showing
tongue, palate, and the buccopharyngeal tube behind as a
resonator. It is remarkable that although Luciani ('Xi), a
physiologist, figures palatograms of a number of consonants
made by his as well as by others (but not made by means of
a pseudopalate), he does not mention the musculature of
the tongue as a factor in producing them. He, apparently,
did not question the assumption, that the extrinsic muscles
which function in vowel production do so for consonants
also.
If one separates one's teeth slightly while observing in the
mirror the formation of the palatodental consonants, one
will note that the tongue as a whole is not moved about.
Little more than the point moves. Hence, in palatodental
contacts which would produce a palatogram, a dorsal surface
deformation would seem to be highly probable, rather than
a movement of the whole tongue, which is a function of the
extrinsic muscles. I n a relatively motionless tongue, only
MUSCLE FIBERS O F T H E TONGUE
71
the intrinsic musculature could operate to broaden or narrow
a contact region in passing from one consonant to another.
The intricate and confused description of the tongue’s musculature in the literature does not call to mind any regularity
of vectors which would produce the proper architecture for
the production of consonants. But when one examines a series
of palatograms and a series of gross muscle bundle sections,
an architecture for impressing the palate specifically becomes
apparent. It is, thus, by assessing the tongue musculature
from the point of view of the phonetician (that is, speech
function), and by analyzing its intrinsic architecture as a
fluid structure, that the possibilities of its movement and
contact with the palate can be recognized.
LITERATURE CITED
BARTH,E.
1911 Einfuhrung in die Physiologie, Pathologie und Hygiene der
meschlichen Stimme. G. Thieme, Leipzig.
BLANDIN, M. F. 1823 Memoire sur la structure et les mouvements de la
langue en l’homme. Arch. Generale de Medicine, I series, 457-470.
BRAUS, H. 1924 Anatomie des Menschen. J. Springer, Berlin. Vol. 2.
CRUVEILHEIR,
J. 1844 Anatomy of the Human Body. Translated by G. S.
Pattison. Harper and Bros. New York.
CUNNINGHAM,
D. J. 1951 Text-book of Anatomy. Edited by Brash and
Jamieson. Oxford University Press. London.
DABELOW,ROSWITHA 1951 Preliminary studies of the tongue as a functional
system. Morph. Jahrb., 91: 33-76.
GRAY,H. 1954 Anatomy of the Human Body. 26th Ed. by C. M. GOSS. Lea
and Febiger, Philadelphia.
GRUTZNER,P. 1879 In Hermann’s Handbuch, “Physiologie der Stimme und
Sprache. ” F. C. W. Vogel, Leipzig, 2: 1-230.
GUTZMANN,
H. 1909 Physiologie der Stimme und Sprache. Ab. 2, Brunswick.
HESSE,
FR. 1875 Uber die Muskeln der menschlichen Zunge. Zeitsch. f . Anat.
u. Entwick, 1: 80-160. Plates 111, IV.
KRAUSE, W. 1879 Handbuch der menschlichen Anatomie. Hahnsche Buchhandlung, Hannover, 9 : 397-407.
LUCIANI,
L. 1915 Human Physiology. Translated by F. A. Welby. Macmillan
and Co. Ltd. London, 3: 164-170.
POIRIER
ET CHARPY 1901 Trait6 d’Anatomie Humaine. Masson e t Cie., Paris,
4 : 93-137.
PONS-TORTELLA,
E. 1936 Zur Entwicklung der Form und der Muskulatur der
Zunge beim Menschen. Zeitsch. f. Entwick, 105: 75-78.
72
LEON H. STRONG
ROUSSELOT,
R. J. 1899 Etudes de pronunciations parisiennes, les articulations
BtudiBes B l’aide du palais artificiel. Le Parole, 9: 481-513.
1910 Prineipees de Phonhtique Experimentelle. Nouvelle Ed., Paris.
ROUVI~RE,
H. 1943 Anatomie Humaine. Masson et Cie., Paris, 1 : 408-411.
SALTER,H. H. 1852 Todd’ Cyclopaedia of Anatomy and Physiology, Tongue.
Longman, Brown, Green and Longmans, London, 4 : 1120-1163.
SHOHARA,
H., AND C. HANSEN 1941 Palatography as a n aid t o the improvement
of articulatory movements. J. of Speech Disorders, 6 115-124.
SOMMERING,
S. T. 1841 Vom Bau des menschlichen Korpers. Muskellehre. L.
Voss, Leipzig, 3: 1-392.
STRONG,
L. H., AND E. M. GOLD 1950 Force components of the tongue musculature
with emphasis on the intrinsic fibers, especially those used in speech.
Anat. Rec., 106: 86.
.-
PLATES
PLATE 1
EXPLAh’hTION 01’ FIGURES
6
Photo. 44 1110. fetus, Homo. Decussation tl~rongh midline of bundles, just
back of tongueti?.
7
Photo. 38 day Homo. Deeussation as i n figure 6.
74
PLATE 1
MCSCLE FIBERS OF THE TONGUE
LEON H. STRONG
75
8 Photo. 43 mo. Homo. Frontal section dissected, just back of frenulum showing complete
bundles of fibers from sept,um to dorsum of aponeurosis.
EXPLASATION OF FIGURES
PLATE 2
LEON H.STRONG
MUSCLE F I R E R S OF THE TONGUE
PLATE 2
PLATE 3
EXPL.?NA’PION
9
OF PIGURES
Photo. 44 mo. fetus, Homo. Frontal section through middle of dorsum.
1 0 Photo. 44 mo. fetus, Homo. Frontal section, through first fetal molar.
78
PLATE
79
3
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