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Head posture and craniofacial morphology.

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Head Posture and Craniofacial Morphology
BEN1 SOLOW AND ANTJE TALLGREN
The Institute of Orthodontics, Royal Dental College, D K - 2 1 0 0 ,
Copenhagen, Denmnrk
KEY WORDS Head posture
cephalometry . Male adults.
.
Craniofacial morphology
.
X-ray
ABSTRACT
The associations between craniofacial morphology and the posture of the head and the cervical column were examined in a sample of 120
Danish male students aged 2 2 3 0 years. Two head positions were recorded on lateral cephalometric radiographs, one determined by the subject's own feeling of a
natural head balance (self balance position), and the other by the subject looking
straight into a mirror (mirror position). Craniofacial morphology was described
by 42 linear and angular variables, and postural relationships by 18 angular variables.
A comprehensive set of correlations was found between craniofacial morphology
and head posture. The correlations were similar for both head positions investigated. Of the postural variables, the position of the head in relation to the cervical
column showed the largest set of correlations with craniofacial morphology. Extension of the head in relation to the cervical column was found in connection with
large anterior and small posterior facial heights, small antero-posterior craniofacial dimensions, large inclination of the mandible to the anterior cranial base
and to the nasal plane, facial retrognathism, a large cranial base angle, and a
small nasopharyngeal space.
The possible role of functional factors in mediating the relationship between
morphology and posture was discussed.
An improved understanding of the coordinating mechanisms which contribute to a
normal craniofacial development is of importance for diagnosis and treatment of
morphological and functional disturbances
in the masticatory system and adjoining regions. A factor which may be of relevance
in this connection is the relationship between craniofacial morphology and the posture of the head.
The question of a relationship between
head form and posture has been the subject
of considerable interest in the anthropological literature. Particular attention has been
devoted to the phylogenetic implications of
the simultaneous development of the brain,
the cranial base flexion and the erect posture in man (Virchow, 1857; Bolk, '15;
Cameron, '27; Kraus, '27; Dabelow, '29, '31;
Weidenreich, '24, '41; Schultz, '42; de Beer,
'47; DuBrul, '50; Delattre and Fenart, '59,
'60; Riesenfeld, '66a). Experimentally, the
presence of a relationship between morphology and posture has been supported by the
demonstration of craniofacial morphologiAM. J. PHYS.ANTHROP.,44: 4 1 7 4 3 6 .
cal changes in animals following artificially
induced changes in body posture (Lisowski
et al., '61; Moss, '61; Riesenfeld, '66b, '69).
In the orthodontic literature only few authors have considered the possibility of a relationship between head posture and craniofacial morphology. Bjork ('55, '60, '61) in
his roentgen cephalometric studies of individual variations in craniofacial growth
drew attention to divergencies in head posture related to different facial types. Bench
('63) in a cephalometric study of the cervical vertebrae observed a relationship between facial form and the curvature and
length of the cervical spine.
In the roentgen cephalometric studies, in
which a natural head position has been recorded (Bjerin, '57; Moorrees and Kean, '58;
Carlsoo and Leijon, '60; Cleall et al., '66;
Fromm and Lundberg, '70), only minor attention has been given to craniofacial morphology and its relation to head posture.
1 Supported by Danish Medical Research Council
grants 512-129169 and 512-581, and by USPHS grant DE02858.
417
418
BEN1 SOLOW AND ANTJE TALLGREN
Cleall et al. ('66) compared the inclination
of craniofacial reference lines to the true
vertical i n samples with normal occlusion
and Class I1 malocclusion, and in a sample
with a swallowing dysfunction characterized
by tongue thrust, and found no significant
differences in head posture between the
groups. Fromm and Lundberg ('70) made
the observation that individuals with a
marked mandibular protrusion carried their
heads in a more downward position than
subjects with normal occlusion. After surgical treatment of the mandibular protrusion
the head position was found to be raised.
With the ultimate purpose of examining
in detail possible associations between head
posture and craniofacial morphology a series of investigations was initiated by the
present authors. I n two previous studies
(Solow and Tallgren, '71a,b) a detailed account is given of the methods developed for
defining, recording and analyzing the postural relationships of the head and cervical
column.
The aim of the present study was to examine the pattern of associations between,
on one hand, the variables describing the
size, shape and position of the craniofacial
components, and on the other hand, the
variables describing the postural relationship of the head to the cervical column and
the relationship of these two components to
the true vertical or horizontal.
the material and the roentgenographic procedure the reader is referred to Solow and
Tallgren ('71a).
Recording procedure and data
processing
The roentgen cephalometric reference
points and lines used in the present study
axe defined in table 1 and are shown in figure 1. In the present study, the reference
points pr, id, as, is, ai, ii, and dms are used
only in the mean facial diagrams.
The reference points were marked with a
pencil on the films and were recorded by a
D-Mac Pencilfollower.:! On the films of head
position 1, the self balance position, all reference points were marked and recorded. On
the films of head position 2, the mirror position, seven reference points were marked
and recorded, the remaining points being
transferred by computer from the films of
position 1 by a specially developed method
described in detail by Solow and Tallgren
('71b). For each film a check of the recorded points was performed by superimposition
of the film on a full size plot of the points,
produced by program PLOTCHECK.
The values of the variables were calculated from the recorded x-and y-coordinates
of the reference points by a modified version
of program COORD (Barrett et al.,'68). No
correction was made for the 5.6% radiographic enlargement. The statistical description of the variables was made accordMATERIAL AND METHODS
ing to Solow ('66).
The present roentgen cephalometric analThe associations between the craniofacial
ysis was performed on lateral head films ob- variables and those describing the postural
tained from 120 Danish male students aged relations of the head and the cervical col22-30 years. For each subject two natural umn were assessed by means of the producthead positions were recorded, one deter- moment correlation coefficients. The 5 %
mined by the subject's own feeling of a nat- and 1% significance levels of the correlaural head balance (position 1, the self bal- tion coefficients were 0.179 and 0.234 for
ance position), and the other by the subject the present sample size of 120 subjects.
fixing his eyes in a mirror i n front of him
The mean facial diagrams in figures 2, 3
(position 2, the mirror position). Both roent- and 6-9 were produced by a program, POLgenographic recordings were made with the REC, which takes asinput meanpolar coordisubject standing in orthoposition -the in- nates for each reference point calculated by
tention position from standing to walking program COORD.
(Molhave, '58).
All calculations were performed at the
The head films were obtained with the aid IBM 370/165 installation at NEUCC, the
of a Lumex type B cephalometric unit which Northern Europe University Computing Cenis vertically adjustable to permit recording tre in Copenhagen.
of standing subjects (Bjork, '68). An 0.5 mm
Method errors
lead wire suspending a weight was mounted
Method errors related to the roentgenoin front of the casette to indicate the true
vertical on the films. For details regarding
2 D-Mac Ltd., Glasgow SW2, Scotland.
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
graphic procedure, the measuring technique
and the reproducibility of the two head positions have previously been reported for representative craniocervical variables (Solow
and Tallgren, ’71a). The method errors
s(i) for the present craniofacial variables
are given in table 2. No systematic errors
were found. The s(i) values ranged from
0.286 to 2.507.
RESULTS
The variables studied are described statistically in tables 2, 3 A and 3B.
The craniofacial morphological variables
are given i n table 2. These variables describe the skull length and height (Nos. 12), the antero-posterior dimensions of the
cranial base (Nos. 3-7), of the maxilla
(Nos. 8-9) and of the mandible (Nos. 1011); and the anterior and posterior vertical
facial dimensions (Nos. 12-15, 16-21). The
angular dimensions express the shape of
the cranial base (Nos. 22-26), the facial
prognathism (Nos. 27-31), the inclination
of maxillary and mandibular bases (Nos.
32-37), the mandibular shape (Nos. 38-39),
and the shape of the bony nasopharynx
(Nos. 40-41). The length of the cervical column is expressed by variable No. 42.
The postural variables (tables 3 A and 3B)
describe the inclination of the craniofacial
reference lines to the true vertical (Nos. 4347) and to the cervical column (Nos. 48-57),
the inclination of the cervical reference
lines to the true horizontal (nos. 58-59),
and the curvature of the cervical column
(No. 60). In the following, the term “extension of the head” is used to denote a raised
position of the head in relation to the cervical column or the true vertical, and the
term “flexion of the head” to denote a forward bent position of the head.
The means and variabilities of most of the
postural variables have previously been
described for both head positions (Solow and
Tallgren, ’71a), and the differences between the two positions have been analysed
(Solow and Tallgren, ’71b). The distribution
form of the morphological and postural variables showed some significant departures
from normality as regards skewness
and kurtosis (b2). However, no systematic
trends were evident, and the magnitude of
the departures from normality was generally moderate.
The correlation coefficients obtained be-
419
tween the craniofacial morphological variables and the postural variables are given for
both head positions in tables 4A and 4B. In
the interpretation of these coefficients, the
correlations between variables which are topographically related, having a reference
point or a reference line in common, should
be distinguished from those between variables which have no point or line i n common.
This distinction is necessary because variables which have reference points i n common may be correlated even if all reference
points vary independently (Solow, ’66). Such
correlations are termed topographical, while
correlations due to coordinated variation of
reference points that are not common to
both variables are termed non-topographical, and are assumed to reflect biological
coordinating mechanisms. For a given pair
of variables, topographical and non-topographical effects on the correlation are not
mutually exclusive, but may reinforce or
counteract each other according to whether
they have the same or opposite sign.
As the aim of the present study has been
to elucidate biological relationships, main
emphasis has been given to the non-topographical correlations. The analysis has
been based mainly on the significant correlations in the groups of variables representing similar morphological dimensions or
postural relationships. However, lower correlations have also been taken into account,
because groups of similar correlations support the observed associations, even though
all the individual coefficients do not reach
the level of significance.
The analysis showed that the correlation
coefficients were similar i n the two head
positions investigated. No distinction is
made, therefore, between the findings in
the two head positions.
In the description of the results given below, Part I reports the correlations displayed
by the postural variables involving the craniofacial reference lines NSL, NL and FML,
and the cervical reference lines OPT and
CVT. Part I1 reports the correlations displayed by the postural variables involving
the mandibular reference lines ML and RL.
(a)
Part I
Correlations between craniofacial
morphology and craniocervical posture
Skull length and height. The length and
height of the skull (n-l and ba-br) showed
no significant correlations with the postural
420
BEN1 SOLOW AND ANTJE TALLGREN
variables apart from some topographical
correlations between variables having the
reference point ba in common.
Antero-posterior craniofacial dimens ions.
The cranial base lengths ( n s , s-ba, n-ba,
n-cd, n-ar) and the lengths of the maxilla
(ss-pm, sp-pm) and the mandible ( p g n x d ,
pg-tgo) showed negative topographical and
non-topographical correlations with the inclination of the foramen magnum line to
the true vertical and the cervical column
(FML/VER, FML/OPT, FML/CVT).
Negative non-topographical correlations
were also found between the anterior cranial base length ( n s ) and the inclination
of NSL and NL to the cervical column, and
between the jaw lengths and NSL/VER.
Vertical facial dimensions. The anterior
upper, lower and total facial heights n-ss,
sp-gn, and n-gn showed marked positive
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
42 1
TABLE 1
Reference points and lines on the cephalometricfilms
Reference points
The apex of the root of the lower central incisor.
ai
Articulare. The intersection between the external contour of the cranial base and
ar
the dorsal contour of the condylar head or neck.
The apex of the root of the upper central incisor.
as
Basion. The most postero-inferior point on the anterior margin of foramen magba
num.
Bregma. The midpoint of the coronal suture on the external cranial contour.
br
Condylion. The most supero-posterior point on the condylar head.
cd
cv2
The apex of the odontoid process of the second cervical vertebra.
cv2 t g
The tangent point of OPT on the odontoid process of the second cervical vertebra.
cv2 ip
The most postero-inferior point o n the corpus of the second cervical vertebra.
cv4 iP
The most postero-inferior point on the corpus of the fourth cervical vertebra.
The distobuccal cusp of the upper first molar.
dmS
Gnathion. The most inferior point on the mandibular symphysis.
gn
Infradentale. The most antero-superior point on the lower alveolar margin.
id
Incision inferius. The midpoint of the incisal edge of the most prominent lower
11
central incisor.
Incision superius. The midpoint of the incisal edge of the most prominent upper
is
central incisor.
Lambda. The midpoint of the lambdoid suture on the external cranial contour.
1
The posterior tangent point of ML.
mlp
Nasion. The most anterior point of the frontonasal suture.
n
Opisthion. The most antero-inferior point on the posterior margin of foramen
0
magnum.
Pogonion. The most anterior point on the mandibular symphysis.
Pg
Prognathion. The point on the mandibular symphysis farthest from cd.
pgn
Pterygomaxillare. The intersection between the nasal floor and the posterior conpm
tour of the maxilla.
Prosthion. The most antero-inferior point on the upper alveolar margin.
pr
The lower tangent point of RL.
rli
The upper tangent point of RL.
rls
Sella. The centre of the sella turcica. The upper limit of the sella turcica is defined
S
as the line joining the tuberculum and dorsum sellae.
Supramentale. The most posterior point on the anterior contour of the lower
sm
alveolar process.
Spinal point. The apex of the anterior nasal spine.
SP
Subspinale. The most posterior point on the anterior contour of the upper alss
veolar process.
The point of intersection between M L and RL.
tpo
Vl
The lower point on the vertical line.
The upper point on the vertical line.
vs
Reference lines
CVT
Cervical vertebrae tangent. The posterior tangent to the odontoid process through
cv4 iP.
FML
Foramen magnum line. The line through ba and 0.
FMP
Foramen magnum perpendicular. The perpendicular to FML.
True horizontal line. The line perpendicular to VER.
HOR
MBL
Mandibular base line. The line through pgn and cd.
ML
Mandibular line. The tangent to the lower border of the mandible through gn.
Nasal line. The line through sp and pm.
NL
NSL
Nasion-sella line. The line through n and s.
OPT
Odontoid process tangent. The posterior tangent to the odontoid process through
C V ip
~.
RL
VER
Ramus line. The tangent to the posterior border of the mandible.
True vertical line. The vertical line projected on the film.
topographical and non-topographical correlations with the position of the head in relation to the cervical column (NSL, NL and
F M L in relation to OPT and CVT), and negative correlations with the inclination (OPT/
HOR, CVT/HOR) and curvature (OPTKVT)
of the cervical column. Apart from some
topographical correlations, the anterior facial heights showed no significant correlations with the position of the head in relation to the true vertical.
The posterior vertical dimensions s-pm,
422
BEN1 SOLOW AND ANTJE TALLGREN
TABLE 2
Morphological variables
Variable
No.
Min
Max
1
2
3
4
5
6
7
8
9
10
179.9
141.9
66.9
42.3
100.1
84.2
91.7
46.5
52.6
111.7
71.4
49.5
56.3
58.7
112.8
44.5
17.2
29.3
55.2
45.2
73.9
114.4
114.9
113.1
78.4
110.6
72.8
68.4
69.6
- 2.8
- 5.4
1.2
39.3
6.7
4.7
77.5
66.9
19.0
107.1
63.9
43.8
69.9
213.4
164.2
82.2
57.5
127.9
107.7
113.1
59.7
65.4
144.2
98.6
63.8
73.6
88.5
142.4
57.9
34.8
47.4
77.5
68.0
105.7
144.9
148.7
135.9
106.5
150.4
92.5
90.0
95.0
6.4
6.1
15.6
64.6
41.7
30.9
98.6
92.5
35.0
137.0
84 .O
71.0
87.9
n-1
ba-br
n-s
s-ba
n-ba
ndd
n-ar
ss-pm
sp-pm
pgn-cd
pg-tgo
n-sp
n-ss
sp+n
n-gn
s-pm
s-cd
s-ar
cd-tgo
ar-tgo
s-tgo
n-s-ba
n-s-cd
n-s-ar
NSLIFMP
s-ba-o
s-n-ss
s-n-sm
s-n-pg
ss-n-sm
ss-n-ue
NSL/Nf.
NSL/MBL
NSLIML
NLlML
NSLlRL
NLIRL
MBLlML
MLlRL
n-s-pm
pm-s-ba
cv2ap-cv4 ip
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
X
193.50
153.03
75.15
49.08
112.68
94.95
101.69
53.41
58.65
126.64
83.02
56.39
64.00
71.79
126.62
50.53
26.67
38.71
68.54
56.09
90.29
129.22
132.04
123.48
92.26
126.96
82.22
79.99
81.42
2.23
0.80
8.04
55.15
27.56
19.52
86.74
78.70
27.59
120.82
72.33
56.89
78.67
Skewness
S.D.
6.71
4.56
3.01
2.91
4.43
4.26
4.33
2.74
3.07
5.58
5.13
3.09
3.57
5.24
6.27
3.00
3.56
3.57
4.40
4.61
5.94
5.03
6.83
4.67
5.51
5.84
3.52
3.52
3.86
2.20
2.81
3.08
4.40
6.20
5.71
4.82
4.63
3.29
6.79
3.46
4.90
3.70
V
m
0.190
- 0.103
0.040
- 0.003
0.138
0.117
- 0.029
-0.369 I
- 0.098
0.089
0.204
0.051
0.176
0.180
0.022
0.185
- 0.165
- 0.219
-0.170
0.039
0.116
- 0.086
0.245
- 0.013
-0.011
0.522 2
0.079
-0.158
0.099
- 0.207
- 0.044
0.150
- 0.253
- 0.231
-0.105
0.032
0.197
- 0.226
0.154
0.306
0.081
0.261
Kurtosis
b2
Method
error
s(i)
2.73
2.87
2.82
3.28
3.27
2.96
2.56
2.67
2.20 2
3.33
3.15
2.54
2.62
2.94
2.53
2.47
2.68
2.57
2.69
3.14
2.92
3.67
2.83
2.93
2.65
4.68 2
3.67
3.66
3.72 1
2.31 1
2.33 I
2.84
3.34
3.01
2.28 1
2.24 2
2.89
2.65
2.65
3.70 1
3.24
2.80
0.654
0.560
0.286
0.591
0.679
1.075
0.702
0.498
0.809
1.203
0.704
0.366
0.850
0.312
0.342
0.356
0.999
0.428
1.351
1.194
0.487
0.573
2.507
0.649
1.176
1.189
0.545
0.412
0.390
0.390
0.344
0.475
0.439
0.361
0.457
0.677
0.719
0.325
0.619
0.478
0.570
0.739
m,
Sample size for statistical description = 120. Sample size for s(i) = 21. s(i) =
where d rep.
resents the difference between double determinations of the same subject, and n the sample size. The variables are given in mm or degrees.
I p s 0.05,
2 ps0.01.
cd-tgo, ar-tgo and s-tgo generally showed
negative topographical and non-topographical associations with the inclination of
NSL to the true vertical and the cervical
column. No significant associations were
found between the posterior vertical dimensions and the inclination or curvature
of the cervical column.
Thus, on the average, extension of the
head in relation to the cervical column was
seen in connection with large anterior and
small posterior facial heights, while flexion
of the head was seen in connection with
small anterior and large posterior facial
heights.
Cranial base flexion. The flexion of the
cranial base (n-s-ba, n-s-cd, ns-ar)
showed positive topographical correlations
with the inclination of NSL to the true vertical and the cervical column. Negative
non-topographical associations were found
between n-s-cd and the inclination of FML
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
423
TABLE 3A
Postural variables. Self balance position (pos. 1)
-
Skewness
Variable
No.
Min
Max
X
S.D.
NSLlVER
NL/VER
FMLlVER
RLlVER
ML/VER
N SLIOPT
NSLlCVT
NL/OPT
NL/CVT
FMLlOPT
FMLiCVT
RLlOPT
RLlCVT
MLlOPT
MLlCVT
OPT/HOR
CVT/HOR
OPT/CVT
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
73.5
68.0
66.9
-9.9
43.0
74.4
82.7
66.9
75.2
70.5
76.4
-9.7
-3.8
50.3
52.4
72.7
73.8
-2.9
111.6
99.3
102.1
16.1
77.7
105.9
111.9
95.9
101.2
107.6
109.6
18.8
23.1
85.8
90.5
103.3
96.2
12.7
89.57
81.53
87.31
2.83
62.01
91.41
96.48
83.37
88.44
89.14
94.22
4.66
9.74
63.84
68.92
88.16
83.08
5.08
5.23
5.02
6.10
5.80
7.00
5.97
5.74
5.77
5.56
7.20
7.03
5.89
5.67
6.43
6.93
6.14
5.39
2.63
Kurtosis
b2
m
0.191
0.032
-0.516 2
0.074
-0.217
- 0.258
- 0.077
- 0.255
0.051
- 0.265
-0.162
- 0.249
- 0.092
0.621 2
0.547 2
0.212
0.272
- 0.271
5.35 2
3.60
3.94 1
2.74
3.11
2.84
2.71
2.59
2.34 1
2.98
2.68
2.53
2.52
3.64
3.55
2.60
2.07 2
3.37
Sample size = 120.
'ps0.05.
pso.01.
2
TABLE 3B
Postural variables. Mirror position ( p o s . 2 )
Skewness
-
Variable
No.
Min
Max
X
~
NSLlVER
NLlVER
FML/VER
RLlVER
ML/VER
NSLlOPT
NSLiCVT
NL/OPT
NL/CVT
FMLlOPT
FM L/ C VT
RL/OPT
RLlCVT
ML/OPT
~ . -~~ - .
MLlCVT
OPT/HOR
CVT/HOR
OPTlCVT
~~
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
~~
~
78.7
73.5
76.5
-6.7
47.8
73.1
82.5
65.6
75.0
72.0
79.4
- 7.2
-0.8
52.2
56. I
77.0
75.2
-2.6
111.9
99.5
108.7
18.8
79.2
104.7
110.8
95.9
101.8
109.0
113.2
18.9
23.6
86.4.
91.6
105.0
97.7
11.9
~~
92.59
84.55
90.33
5.85
65.02
92.18
97.71
84.13
89.67
89.91
95.45
5.44
10.97
64.61
70.15
90.41
84.87
5.54
4.73
4.69
6.28
5.49
6.60
6.00
5.65
5.81
5.54
7.39
7.23
5.89
5.63
6.25
6.65
5.89
5.19
2.57
Kurtosis
b2
a
S.D.
~
_
_
_
0.199
0.104
0.199
0.006
- 0.333
-0.354 1
- 0.261
-0.331
- 0.045
- 0.084
- 0.057
- 0.259
- 0.037
0.562 2
0.532 2
0.135
0.168
- 0.330
_
4.79 2
2.85
2.80
2.59
2.62
3.07
2.84
2.68
2.23 2
2.81
2.51
2.28 1
2.32 I
3.41
3.42
2.54
2.33 1
3.29
~
Sample size = 120.
1 pC0.05.
zpso.01.
to the true vertical and the cervical column.
The inclination of the foramen magnum
line to the anterior cranial base (NSL/FMP)
and to the posterior cranial base (s-ba-o)
showed positive, respectively negative nontopographical correlations with the inclination of the nasal line (NL) to the true vertical and the cervical column. In addition,
topographical correlations were observed
with the postural variables involving NSL
and FML.
Thus, on the average, a backward upward slope of the foramen magnum line in
relation to the cranial base, was seen in
connection with extension of the head (NSL,
NL) in relation to the true vertical and the
424
BEN1 SOLOW AND ANTJE TALLGREN
TABLE 4A (Part11
Correlations between postural and morphological variables
Linear morphological variables
Postural
variables
No.
Head
pos.3
n-1
ba-br
n-s
1
2
3
-00
-05
-04
03
~
s-ba
_ _ __
___
4
n-ba
n-cd
5
6
__ __
n-ar
~
7
ss-pm
sp-pm
pgn-cd
8
9
10
pg-tgo
11
-05
-15
-252
-292
-14
-201
01
-09
-12
-14
-02
-07
- _ _ - __
~~
NSL/
VER
43
1
2
-05
-09
NLI
VER
44
1
2
-03
-06
FML/
VER
45
NSL/
OPT
48
NSLl
CVT
49
NL/
OPT
50
NL/
CVT
51
FMLI
OPT
1
2
05
02
00
07
11
oa
-07
-201
09
06
01
-01
09
04
-14
-252
09
-03
05
00
02
-01
09
04
-11
-21
-242
1
-14
-17
-16
-09
-332
-292
-312
-17
-17
-15
-19'
-252
-312
-221
-292
-232
-232
-15
-18'
1
2
-11
-15
- 09
- 17
-191
-21 1
-05
-12
- 07
- 13
-10
-14
-03
-07
-06
-09
-02
-02
-13
-181
-13
-181
1
-13
-17
- 09
- 17
-17
-20
-08
- 17
- 05
2
- 12
-05
-09
04
-01
-07
-11
-03
-06
-16
-211
-06
-13
1
2
-10
-13
-0 7
08
01
- 11
- 17
-10
-14
-04
-08
-03
-06
03
03
-01
-06
-08
1
-11
-15
- 07
-14
-17
06
-02
- 09
2
- 16
-05
-09
03
-02
-03
-08
02
-01
-03
-08
05
-02
52
1
2
-02
-04
- 19
-25 2
-262
-272
-201
-252
-372
-402
-242
-252
-221
-252
-16
-18'
-17
-17
-12
-16
-13
-17
FMLI
CVT
53
1
2
-03
-05
- 19 I
-25 2
-262
-23 2
-282
- 36 2
-392
-201
-221
-17
-201
-17
-19
-181
-20 1
-14
-18
OPT/
HOR
58
15
11
1 8 1
13
11
11
-06
-10
-03
-10
-09
-05
CVTI
HOR
59
14
181
07
09
05
06
-07
-10
-01
-07
-08
-04
OPT/
CVT
60
-04
-07
-06
-04
16
15
M LI
-16
-191
01
02
'
-25
1
2
1
-02
1
-08
-12
~
2
07
08
09
14
15
242
1
2
09
10
09
14
15
242
1
-01
-03
02
00
01
02
-07
-05
2
-03
-02
02
02
04
05
-06
-07
06
04
11
11
15
14
-00
-02
47
1
2
01
-01
17
15
19 1
252
07
-01
15
12
262
262
342
322
01
-05
10
03
-13
-15
272
252
M LI
OPT
56
1
2
-05
-09
11
03
07
04
08
02
02
-04
19'
15
272
242
07
04
13
13
-05
-11
292
24 2
MLI
CVT
57
1
2
-06
-09
11
04
08
06
05
-01
04
-02
21 1
191
3 1 2
282
06
03
09
11
-07
-12
332
292
RLI
VER
46
11
08
07
13
08
-02
07
04
10
09
10
06
-14
-232
01
-08
00
-01
-252
-302
RLI
OPT
54
1
2
-02
-05
02
-06
-09
-11
09
02
-09
-14
-08
-11
03
02
10
04
-252
-302
RLI
CVT
55
1
2
-03
-06
03
-05
-08
-10
07
-02
-07
-13
-08
-13
02
-01
07
02
-18
-25
08
08
11
11
VER
C V ~ ~ P - 42
CV4'P
1
1
2
1
2
06
04
17
181
191
21 1
05
04
322
342
13
13
-01
-05
-02
-06
04
00
05
00
10
10
13
13
11
10
1
2
02
03
Sample size = 120. The decimal points of the correlation coefficients have been omitted.
1 p c 0.05.
zpco.01.
3 m e correlation coefficients have been given for both head positions investigated: position 1, the self balance position, and
position 2, the mirror position (for definitions, p. 418).
425
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
TABLE 4A (PartZ)
Correlations between postural and morphological variables
Linear morphological variables
Postural
variables
n-sp
No.
Head
pos.3
__
12
19 1
09
n-ss
13
sp-gn
14
232
20 1
s-pm
n-n
- -
___
15
06
02
11
04
02
-04
14
10
01
-07
05
-00
01
-03
03
-03
NSL/
VER
43
1
2
NLI
VER
44
1
2
-16
-292
FML/
VER
45
1
2
05
-04
NSL/
OPT
48
1
2
282
262
482
442
322
312
NSL/
CVT
49
1
2
252
21'
422
392
NLI
OPT
50
1
2
-02
-04
NLI
CVT
51
1
2
-06
-10
FML/
OPT
52
1
2
FML/
CVT
53
OPT/
HOR
sxd
s-ar
__
~
cd-tgo
~
ar-tgo
s-tgo
__
~
16
17
18
19
-282
-332
-13
-262
-05
-17
-181
-242
-252
-342
-201
-342
-03
-08
-16
-232
-02
-13
05
04
-02
-13
13
02
21
20
-06
-07
03
-06
-02
-11
-21 1
-242
-12
-17
-07
-16
372
342
-211
-232
-09
-12
-03
-07
-181
-232
-232
-202
-15
-211
242
232
292
262
-232
-252
-04
-09
02
-03
-13
-201
-181
-242
-09
-17
302
262
402
302
272
08
06
01
-02
12
08
-05
-11
-15
-201
01
-05
242
191
322
302
21
08
05
06
02
18 1
13
01
-06
-09
-15
14
12
272
232
232
211
252
232
-03
-04
05
02
-01
-04
-191
-242
-11
-15
-04
-09
1
2
11
07
21
17
16
14
181
15
-03
-05
09
05
03
-01
-16
-20'
-07
-11
01
-05
58
1
2
-11
-191
-272
-292
-262
-302
-272
-322
-03
-03
-03
-09
-01
-06
CVTl
HOR
59
1
2
-09
-15
-232
-242
-201
-242
-21 1
-252
-03
-02
-08
-14
-07
-12
OPT1
CVT
60
1
2
-08
-13
-16
-19'
-21
-21
-201
-22'
-01
-01
10
09
MU
47
1
2
-17
-272
-302
-362
-422
-492
-432
-512
-01
-02
21
14
1
2
-08
-10
-07
-11
-21 1
-232
-211
-242
-00
VER
M L/
56
OPT
1
3 8 2
1
1
1
181
02
02
04
-03
-01
08
00
-03
-06
01
01
-05
-05
-10
-12
11
10
12
11
14
12
14
12
3 1 2
242
392
382
31 2
282
41 2
352
252
22 1
342
31 2
412
372
3 3 2
292
472
422
272
242
362
332
422
392
362
322
492
442
1
M LI
CVT
57
1
2
-11
-15
-13
-17
-272
-302
-272
-31
01
-01
RL/
VER
46
1
2
-08
-15
-211
-17
-232
-181
-262
-04
-06
03
-06
11
02
-12
-16
-191
-262
-17
-282
RLI
OPT
54
1
2
04
02
13
10
10
09
10
07
-01
-03
06
03
13
08
-14
-191
-20 1
-252
-14
-21'
RLI
CVT
55
1
2
01
-04
06
02
01
-00
01
-02
-01
-04
11
07
181
13
-09
-15
-15
-21
-08
-16
~
2
CV4lP
42
~
19 1
201
232
232
~1
2
-181
-
292
302
252
252
11
11
232
232
282
272
03
04
02
03
1
15
16
Sample size = 110. The decimal points of the correlation coefficients have been omitted.
1 p S 0.05.
2 p s 0.01.
3 The correlation coefficients have been given for both head positions investigated: position 1, the self balance position, and
position 2, the mirror position (for definitions, p. 416).
BEN1 SOLOW A N D ANTJE TALLGREN
426
TABLE 4B (Part I )
Correlations between postural and morphological variables
Angular morphological variables
Postural
vanables
NSLl
No.
Head
pos.3
n-s-ba
n-s-cd
__ __
22
__
___
24
25
43
1
2
NLI
VER
44
1
2
-02
-05
08
10
FMLl
VER
45
1
2
-10
-12
-201
-18'
NSLl
OPT
48
1
2
15
15
211
221
242
252
22'
181
NSL/
CVT
49
1
2
211
211
232
252
302
302
NL/
OPT
50
1
2
-13
-13
02
04
NLI
CVT
51
1
2
-08
-09
03
05
FML/
OPT
52
1
2
-18'
-17
-21'
-191
FML/
CVT
53
1
2
-13
-14
OPT/
HOR
58
1
2
CVT/
HOR
59
OPT/
s-n-ss
s-n-sm
s-n-pg
ss-nsm
ss-npg
NSLl
30
31
32
NL
- __ - - - - 26
27
28
29
-08
01
-392
-482
-492
-542
-482
-542
16
09
18 1
13
252
13
-252
-16
-11
-17
-17
-17
-15
-16
10
01
08
02
-08
-13
-11
-11
-09
-09
04
-03
01
-04
-08
-04
-372
-382
-462
-492
-492
-522
14
16
201
232
322
322
221
16
-03
03
-342
-432
-452
-372-452-492
13
13
19 1
211
332
312
11
08
-221
-18'
-13
-14
-181
-201
-20'
-232
08
10
11
15
-20 1
-201
12
05
-181
-12
-09
-11
-13
-15
-15
-18'
07
07
10
12
-221
-242
-11
-10
-592
-602
402
422
-10
-11
-12
-14
-12
-15
04
04
05
07
11
11
-201
-18'
-07
-07
-602
-642
462
482
-06
-08
-08
-10
-08
-11
02
02
03
04
11
09
11
09
05
05
04
-01
09
03
1
2
07
05
04
04
-01
-06
11
06
60
1
2
12
11
03
03
11
09
47
1
2
-03
-06
-00
01
05
01
15
06
MLI
OPT
56
1
2
-14
-14
-05
-04
02
02
MLI
CVT
57
1
2
-08
-09
-04
-02
06
06
RLI
VER
46
1
2
-04
-07
10
12
RLI
OPT
54
1
2
-15
-15
RLI
CVT
55
1
2
-10
-11
C V ~ ~ P -
42
1
-15
-16
VER
322
292
s-ba-
362
262
--MLI
292
342
FMP
NSLl
VER
CVT
302
302
23
n-s-ar
01
-05
-09
-13
-03
-03
02
02
-602
-682
482
542
~01
05
03
00
362
342
-242
-31 2
13
08
03
06
06
10
00
-09
-05
-13
-01
-05
-02
00
01
05
02
-06
-03
-11
00
-03
10
08
12
14
12
14
-03
-08
-04
-08
-02
-06
-17
-11
10
07
11
13
232
252
-03
-09
-201
-252
-09
-13
07
04
-191
-16
08
07
10
08
201
17
-03
-01
-17
-14
-09
-10
07
02
-13
-09
11
10
13
13
232
211
-04
-04
-17
-16
-09
-11
-03
-09
13
02
-16
-08
07
08
08
-08
-16
-252
-15
-221
01
-04
05
06
-08
-07
03
-00
-16
-13
-06
-08
04
01
02
-02
-16
-14
-10
-07
02
01
06
08
-03
-03
03
-03
-12
-07
-02
-05
09
07
07
04
-18 1
-191
-12
-11
01
-01
-11
-10
-06
-03
-08
-11
01
01
00
00
03
03
-01
-06
-05
-02
11
15
-01
-04
_.
cv4'P
2
-15
-15
-03
03
02
08
03
02
-03
-02
Sample size = 120.The decimal points of the correlation coefficients have been omitted.
'p,CO.O5.
*pso.01.
3 The correlation coefficients have been given for both head positions investigated: position 1 , the self balance position, and
Position 2, the mirror position (for definitions, p. 418).
42 7
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
TABLE 4B (Part21
Correlations between postural and morphological variables
Angular morphological variables
Postural
variables
No.
Head
p0s.3
NSL/
MBL
NSLl
ML
-
__
33
34
NLlML
NSL/
RL
35
36
- -
NL/RL
MBLl
ML
ML/RL
n-spm
__
__
___
__
37
38
39
40
04
-00
-00
03
41
cv~a*cv41P
__
42
NSL/
VER
43
1
2
392
41 2
26 2
302
09
14
342
342
11
13
NLI
VER
44
1
2
11
10
02
03
15
21 1
12
09
282
FML/
VER
45
1
12
10
10
11
05
08
08
06
00
01
-04
-07
04
06
NSLl
OPT
48
542
572
442
482
312
2
3 5 2
422
422
221
232
-11
-14
11
13
4E2
482
-18
-19
NSL/
CVT
49
1
2
462
502
332
372
18 1
242
442
432
242
242
00
-04
-01
03
422
432
-08
-09
NLI
OPT
50
1
2
302
322
242
282
372
412
232
241
382
-06
-09
06
09
332
342
-372
-372
16
12
NL/
CVT
51
1
21 1
242
12
16
242
30 2
242
232
392
40 2
262
272
-262
-282
06
00
FMLl
OPT
52
262
2E2
272
292
232
262
181
17
11
11
-16
-17
12
14
201
21 1
-332
-322
16
2
FML/
CVT
53
1
2
19'
201
17
191
12
16
181
16
11
11
-06
-09
03
06
15
15
-24 2
-252
08
02
OPT/
HOR
58
CVT/
HOR
59
OPT/
CVT
60
MLI
VER
47
MLI
OPT
56
MLI
CVT
57
RLI
VER
46
RLI
OPT
54
RLI
CVT
55
2
1
2
1
42
C"4iP
382
10
06
06
02
-06
-04
-06
-02
12
17
-12
-252
09
-01
-08
-05
-11
-252
00
-07
-10
-07
-05
-17
1
1
14
10
05
-01
11
-191
-242
-21'
-252
-232
-242
-12
-16
-12
-13
14
14
-10
-11
-242
-342
282
332
-242
-312
-11
-16
-10
-14
-11
2
-14
-16
-15
-15
03
04
01
-01
-191
-302
20'
252
-17
-221
1
2
-21 1
-232
-292
-292
- 3 1 2
-01
-04
-01
272
242
-262
-242
-17
-292
242
242
-21 1
-262
1
2
-472
-512
-692
-732
-712
-722
02
-00
08
09
682
692
-652
-662
-382
18'
211
-16
-242
1
-332
- 3 1 2
-552
-542
-552
2
- 5 3 2
14
15
201
221
602
592
-602
-592
-09
-08
-622
-622
-632
-612
13
12
191
201
662
652
-662
-652
-14
-14
02
01
-03
-07
02
03
01
05
-532
-582
-56%
-582
-252
-302
392
442
-16
-252
07
10
-07
-191
242
272
252
292
-392
-391
-422
-412
-392
-422
492
522
09
10
-22'
-232
181
14
09
03
1
2
-
3 1 2
262
19'
pm-sba
-
1
1
-392
2
-382
1
- 16
2
-19
1
-13
01
-181
-292
-08
-09
2
04
07
1
2
- 06
- 03
11
15
12
17
-412
-422
-432
-432
-2E2
-332
392
442
02
03
-12
-13
1
03
03
07
06
09
08
-05
-04
-03
-03
-10
-09
10
09
16
16
-272
-282
1
2
06
04
Sample size = 120. The decimal points of the correlation coefficients have been omitted.
1 p L 0.05.
2 PB0.01.
3 The correlation coefficients have been given for both head positions investigated: position 1, the self balance position, and
position 2, the mirror position (for definitions, p. 418).
428
BEN1 SOLOW AND ANTJE TALLGREN
cervical column, while a backward downward slope was seen in connection with
flexion of the head.
Facial prognathism. The maxillary and
mandibular prognathism (s-nss, s-n-sm,
s-n-pg)
showed negative topographical
and non-topographical correlations with
the position of the head in relation to the
cervical column and the true vertical.
Thus, on the average, retrognathic jaws
were seen in connection with extension of
the head, and prognathic jaws in connection
with flexion of the head.
Regarding the sagittal jaw relationship
(ss-n-pg), positive non-topographical correlations were found with the inclination of
the nasion-sella line to the cervical column
and the true vertical.
Inclination of the j a w bases. The inclination of the mandible to the cranial base
and to the nasal line (NSLIMBL, NSLIML,
NL/ML, NSL/RL, NL/RL) showed marked
positive topographical and non-topographical correlations with the position of the
head in relation to the cervical column,
and negative associations with the cervical
inclination and curvature. Apart from topographical associations no significant correlations were found with the position of the
head to the true vertical.
Thus, on the average, a small inclination
of the mandible to the cranial base and the
nasal plane was seen in connection with
flexion of the head, backward cervical inclination and increased cervical lordosis, while
large mandibular inclination was seen in
connection with extension of the head, forward cervical inclination and reduced cervical lordosis.
The inclination of the nasal plane to the
cranial base (NSL/NL) showed, apart from
the topographical correlations, no significant associations with the postural relationships of the head and the cervical column.
Mandibular shape. Apart from the topographical correlations, the mandibular
shape (MBLIML and MLIRL) showed significant correlations only with the cervical curvature (OPTICVT), a marked bend of the
mandibular base being associated with a
marked cervical lordosis.
Nasopharyngeat space. The shape of the
bony nasopharyngeal space, as expressed by
the angles n-s-pm and pm-s-ba, showed
positive and negative correlations, respec-
tively, with the position of the head in relation to the cervical column. Although
most of the pairs of variables shared a reference point or a reference line, the sign of
many of the correlations differed from that
which would have been expected topographically, thus indicating the presence of a biological coordinating mechanism. Non-topographical correlations were found with the
cervical inclination and curvature.
The correlations indicated that, on the
average, a proportionally large antero-postenor extent of the nasopharyngeal space was
seen in connection with flexion of the head
in relation to the cervical column, backward cervical inclination and increased cervical lordosis, while a proportionally short
nasopharynx was seen in connection with
extension of the head, forward cervical inclination and reduced cervical lordosis.
Length of the cervical column. m e
length of the cervical column (~v2~p-cv4’p)
was negatively correlated with the position
of the head in relation to the true vertical
and with the cervical inclination and curvature.
Regarding the correlations with the craniofacial morphology, the cervical length
was found to be positively associated with
the upper and total linear vertical dimensions; negative correlations were found
with the shape of the nasopharyngeal space
as expressed by pm-s-ba.
Thus, on the average, a long cervical
column was seen in connection with flexion
of the head in relation to the true vertical,
forward inclination and reduced lordosis of
the cervical column, large vertical facial dimensions, and a proportionally short sagittal extension of the nasopharyngeal space.
A short cervical column was seen in connection with extension of the head, backward
inclination and increased lordosis of the
cervical column, short vertical facial dimensions and a proportionally long nasopharynx.
Part I1 Correlations between craniofacial
morphology and the inclination of the
mandible to the true vertical and
the cervical column
The inclination of the mandibular line to
the true vertical and the cervical column
(MLIVER, MLIOPT, MLICVT), showed positive non-topographical and topographical
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
correlations with the lateral total cranial
base lengths n+d and n-ar, with the length
of the mandibular corpus, pg-tgo, and with
the posterior vertical facial dimensions except s-pm. Negative topographical correlations were found with the anterior lower
and total facial heights (sp-gn, n-gn). In
addition, ML/VER showed positive non-topographical correlations with the anterior cranial base length (n-s), and negative with
the anterior upper facial height (n-sp,
n s s ).
Marked topographical correlations were
found with the angular morphological variables involving ML. Negative non-topographical correlations were found with the
inclination of the mandibular base to the
anterior cranial base, as expressed by NSL/
MBL, and positive correlations with the
mandibular prognathism (s-n-pg). In addition, ML/VER showed negative non-topographical correlations with the sagittal jaw
relationship (ss-n-pg) and negative, respectively positive non-topographical correlations with the nasopharyngeal angles ns-pm and pms-ba.
Thus, on the average, a mandibular line
relatively perpendicular to the cervical column and the true vertical was seen in connection with short anterior and long posterior facial heights, large anterior and lateral
cranial base lengths, a small inclination of
the mandible in relation to the anterior cranial base, and mandibular prognathism,
while a small angulation of the mandibular
line in relation to the cervical column and
the true vertical was seen i n connection
with long anterior and short posterior facial heights, short anterior and lateral cranial base lengths, a large inclination of the
mandible to the anterior cranial base, and
mandibular retrognathism.
The inclination of the ramus line to the
cervical column and the true vertical (RL/
VER, RL/OPT, RLICVT) showed only few
significant correlations with the craniofacial morphological variables. Topographical
correlations were found with the morphological variables involving tgo and RL. Nontopographical correlations with morphological variables involving ML indicated that
a large angulation of the ramus line to the
cervical column was associated with a relatively straight mandibular base and a large
inclination of the mandibular line to the
429
anterior cranial base, while a small angulation of the ramus line to the cervical column, i.e., a relatively great parallelism,
was associated with a marked bend of the
mandibular base and a small inclination of
the mandibular line to the anterior cranial
base.
DISCUSSION
The comprehensive system of associations
between the variates expressing the size,
shape and position of the craniofacial components, and those expressing the postural
relationships of the head and cervical column, clearly indicates a relationship between craniofacial morphology and head
posture.
The magnitudes of the non-topographical correlations rarely exceeded a numerical
value of 0.5.This is consistent with a previous analysis of craniofacial correlations
(Solow, '66). However, despite their moderate magnitude the correlations observed
seem to be of considerable interest in view of
the biological coordinating mechanisms
whose presence they can be taken to indicate.
The fact that similar correlations were
found throughout i n both head positions indicates that the observed relationships between facial morphology and head posture
were not affected by small changes in the
natural head position. Moreover, craniofacial dimensions which biologically could be
considered to represent the same source of
variability, displayed similar correlations.
The main groups of correlations between
the craniofacial morphological variables and
the cranial and cervical postural variables
are summarized in table 5. It is seen from
the table that of the postural variables, the
position of the head in relation to the cervical column (NSL/OPT), displayed the most
comprehensive set of correlations with craniofacialmorphology. The twoextremetypes
of head posture displayed by this variable
are thus of particular interest. One extreme
type is characterized by extension of the
head in relation to the cervical column and
to the true vertical, a forward inclination of
the cervical column and a tendency to reduced cervical lordosis (fig. 2), while the
other extreme type is characterized by flexion of the head in relation to the cervical
column and the true vertical, backward in-
430
BEN1 SOLOW AND ANTJE TALLGREN
TABLE 5
Main groups of significant correlations between craniofacial morphology and postural
relationships of head and cervical column
Postural relationships
Craniofacial morphology
Head to true
vertical
(NSL/VER
NLlVER
FML/VER)
Craniocervical angulation
(NSLIOPT
NLlOPT
FMLIOPT)
Cervical
inclination
(OPTIHOR
CVTIHOR)
Cervical
curvature
(OPTICVT)
Antero-posterior dimensions
Cranial base: n s , s-ba, n-ba,
n-cd, n-ar
Maxilla: ss-pm, sp-pm
Mandible: pgn-cd, pg-tgo
Vertical facial dimensions
Anterior: n-ss, sp-gn, n-gn
Posterior: cd-tgo, ar-tgo, s-tgo
Facial prognathism
Maxilla: s-n--6s
Mandible: s-nam, s-n-pg
Inclination o f j a w bases
Mandible: NSL/ML, NSL/MBL
Mandible to maxilla: NL/ML
Mandibular shape
Gonial angle: ML/RL
MBLlML
-
+
Nasopharyngeal space
n-s-pm
pm-s-ba
+-
+
-
+
M i n . NSI./OP'I'
Max. NSL/OPT
2
-
3
Fig. 2 Mean facial diagram illustrating craniofacial morphology and craniocervical posture in the ten subjects with the largest extension of the head i n relation to the cervical column
(NSLIOPT) in the natural head position (Mirror position). Diagram oriented according to mean
NSLlVER for this subsample (95.9'). In all the mean facial diagrams (figs. 2 3 and 6-9) the
sella point is located 10 cm from the vertical line.
Fig. 3 Mean facial diagram illustrating morphology and posture in the ten subjects with
the most marked flexion of the head i n relation to the cervical column (NSL/OPT) i n the natural head position (Mirror position). Orientation according to mean NSL/VER for this subsample
(89.2").
HEAD POSTURE AND CRANIOFACIAL MORPHOLOGY
431
Fig. 4 Craniofacial morphology of subject HB 003, showing marked extension of the head
i n relation to the cervical column. Radiograph and tracing oriented according to natural head
position (Self balance position). Notice large anterior facial height, large mandibular inclination
and facial retrognathism.
Fig. 5 Craniofacial morphology of subject HB 092, showing marked flexion ofthe head i n relation to the cervical column. Orientation according to the natural head position (Self balance
position). Notice small anterior facial height, small mandibular inclination and facial prognathism.
clination of the cervical column and a ten- facial morphology characterizing these two
dency to increased cervical lordosis (fig. 3). extreme postural types. As illustrated in
The correlations observed may be visual- figure 2, a subject displaying the first exized by a description of the average cranio- treme postural type, a n extension of the
432
BEN1 SOLOW A N D ANTJE TALLGREN
IkFJk\--
?I
tII .: I-----------
,/
- _---,
I
I
\ \
;
~
,
.' .L-=
/-*
'\.
I
II
/-
bI
head in relation to the cervical column, on
the average was characterized by the following craniofacial morphology :
a. large anterior facial height
b. small posterior facial height
c. small antero-posterior craniofacial
dimensions
d. large inclination of the mandible to
the anterior cranial base and to the
nasal plane
e. facial retrognathism
f. large cranial base angle and a backward upward slope of the foramen
magnum line in relation to the cranial base
g. small nasopharyngeal space
A subject displaying the second extreme
postural type, a flexion of the head in relation to the cervical column (fig. 3), was on
the average characterized by a small anterior and a large posterior facial height,
large antero-posterior extension of the craniofacial skeleton, a small inclination of
the mandible to the anterior cranial base
and the nasal plane, facial prognathism, a
small cranial base angle, a backward downward slope of the foramen magnum line in
relation to the cranial base, and a large
nasopharyngeal space.
Individual subjects displaying the two
extreme postural types are shown in figures
4 and 5.
The difference in craniofacial morphology in the two extreme postural groups is
illustrated by the combined mean diagrams
of the subjects displaying the largest extension and flexion of the head in relation
to the cervical column (fig. 6). An impression of the combined effect of the morphological and postural differences in the two
extreme groups is obtained by superimposing the same two mean diagrams according to the recorded natural head position (fig. 7).
To further illustrate the observed relationship between head posture and craniofacial morphology, mean facial diagrams
were derived for the two morphological
groups displaying the largest and smallest
inclination of the mandible to the anterior
cranial base, NSL/ML. Graphical comparisons of these mean diagrams with those in
figures 2 and 3 are shown in figures 8
and 9.
The craniofacial morphology in the group
characterized by a large inclination of the
mandible to the anterior cranial base
showed marked similarity to the morphology
in the group characterized by marked extension of the head in relation to the cervi-
HEAD POSTURE A N D CRANIOFACIAL MORPHOLOGY
433
- Min.
______
cal column (fig. S), and the craniofacial
morphology in the group characterized by a
small NSL/ML was similar to that found in
the group characterized by marked flexion
of the head in relation to the cervical column (fig. 9).
The relationship between craniofacial
morphology and the posture of the head
and cervical column has not previously
been subjected to systematic study. However, Bjork ('55, '60, '61) i n his roentgen
cephalometric studies ofcraniofacial growth
made the observation that individuals with
a flattened cranial base and a retrognathic
facial type carried their head in an extended position, while those with a marked bend
of the cranial base and a prognathic facial
type carried their head with the face lowered. Bjork and Kuroda ('68) using the foramen magnum perpendicular to represent
the balance axis of the head, observed that
in a subject with condylar hypoplasia and
palpebral ptosis, a flattening of the cranial base was accompanied by a change in
head posture so that the face was raised.
Morphologically, the face was drawn in under the anterior cranial base, and the
mandible rotated backwards. Bench ('63) in
a roentgenographic study of growth of the
cervical vertebrae noted a tendency for
NSI./OPT
Min. NSL/ML
the neck to be curved in subjects with
square faces and a straight and long cervical column in subjects with long faces. The
observations by the above mentioned authors are largely in accordance with the
findings in the present investigation.
The correlations observed between the
craniofacial morphology and the inclination
of the mandible to the true vertical and the
cervical column were consistent with and
supplemented the above findings. In particular it may be noted that a facial type
characterized by a relatively straight mandibular base and a large inclination of the
mandibular line to the anterior cranial
base also featured a ramus line with a
large angulation to the cervical column
(figs. 2, 4), while a facial type characterized by a marked bend of the mandibular
base and a small inclination of the mandibular line to the anterior cranial base displayed a ramus line relatively parallel to
the cervical column (figs. 3, 5).
The present finding of an association between craniofacial morphology and craniocervical postural relationships in the natural head position raises several questions.
Which biological mechanisms are responsible for the associations? Do changes in
craniofacial morphology influence cranio-
434
BEN1 SOLOW AND ANTJE TALLGREN
cervical posture; is craniofacial morphology
influenced by postural factors, or are other
biological mechanisms responsible for the
coordinated variation in morphology and
posture ?
Answers to these questions cannot be derived from the present study. However, it
seems reasonable to assume that functional
factors play an important role in this connection, being related to craniofacial morphology as well as to head posture.
Regarding the relationship between craniofacial morphology and functional factors, Moss and Young ('60), Moss ('68),
Moss and Rankow ('68), Moss and Salentijn ('69) emphasized that the morphology
of the craniofacial skeleton is determined
by the surrounding functional matrix. Electromyographically, a relationship between
craniofacial morphologic characteristics
and the degree of muscular activity has
been demonstrated by Mmller ('66). Similar
findings were made by Ingervall and Thilander ('74). An association between craniofacial morphology and bite force was observed by Ringqvist ('73). A relationship
between dentoalveolar morphology and
tongue and lip function has been described
by numerous authors (for review, see for
instance Hanson and Cohen, '73). Furthermore, a relationship between skeletal morphology and adenoidal obstruction has
been observed by, among others, LinderAronson ('70, '74), Dunn et al. ('73), and
Koski and Liihdemaki ('75).
Regarding the relationship between
functional factors and head posture, physiologic functions such as respiration, swallowing and speech, which are dependent
upon the maintenance of a sufficient nasopharyngeal space, may be related to the
craniocervical posture. Bosma ('63) thus
stresses that the postnatal development of
head and neck posture parallels the stabilization of the pharyngeal airway, and
that the development of sight, hearing and
vestibular orientation are other guiding
mechanisms for the stabilization of an upright head posture. In a study of patients
with bulbar poliomyelitis Bosma ('57) also
emphasizes the intimate relationship between the impaired function of the mouth,
pharynx and larynx on one hand, and the
adaptive or compensatory changes in the
posture of head and neck on the other.
Cleall et al. ('66)cinefluorographically examined the relationship between head pos-
ture and swallowing and found small but
significant movements of the head during
swallowing.
Ricketts ('68) reported that in subjects
with excessive adenoid development in the
nasopharynx, a forward and downward
tongue posture and extension of the head
was seen, apparently caused by an effort to
increase the airway. After removal of the
adenoids elevation of the tongue and downward flexion of the head were noted. Queen
and Cleall ('74) found a reduced nasopharyngeal area and extended head position in
subjects with Down's syndrome. The finding
in the present study of a negative correlation between the sagittal extent of the nasopharyngeal space and the craniocervical
angulation is consistent with the observations made by these authors.
The potential of functional factors to mediate the relationship between craniofacial
morphology and craniocervical posture,
demonstrated in the present study, thus
seems to be supported by the literature. On
the other hand, the determination of causal
factors and of the detailed nature of the
mechanisms at work requires further study.
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