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Variations in the articular facets of the cervical vertebrae.

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VARIATIOSS I N T H E ARTICULAR FACETS O F
T H E CERVICAL VERTEBRAE
CARL C. FRANCIS
Department of Anatomy, ?Vestern Reserve University
For a number of years clinicians have been interested in
the relation of arthritis and other degenerative diseases of the
cervical vertebrae to manifestations of nerve irritation and
injury. Ifany studies of this problem have been made. Recently, Overton and Grossman ( ' 5 2 ) suggested the possibility
that anatomical variations in the articulations of the second
and third cervical vertebrae rnay be related to instability of
the intervening joints, and thus may be an additional cause
for clinical manifestations of nerve damage. They studied 36
cadaver specimens, and report that 18 of these showed marked
variations in the plane of articulation, in the angle of inclination, and in the size of the articular facets of the right and
left articular processes. They further state that their series
is too small for a statistical study, but they feel that minor
anatoniical variations do occur frequently in the upper cervical spine. They do not state the age, sex, o r race of any of
their specimens, but do report that degenerative changes were
present in 4 specimens.
Standard anatomical texts describe the cervical vertebrae in
detail and casually mention certain variations. Many extensive studies are available on variations in the total number of
cervical vertebrae, on modifications of the spinous processes,
and on variability of the foramina in the transverse processes.
A careful perusal of the literature failed t o reveal any systematic study of the articular facets in a large series of vertebrae of known age, sex, and race. The documented collection
of human skeletons in the Department of Anatomy, Western
589
590
CARL C. F R A N C I S
Reserve University, contains ample material for such a survey. I t was felt that definite information on the variations of
these portions of the cervical vertebrae is desirablcb bccause
of its possible relationship to clinical prohlems.
MATEBIAL
111 order to avoid the complication of degenei~~tivci
cliaiige
a s innell a s possihle, it was thought best to limit thc study to
Male
A1.E IS TEARS
\ \ 11 i te
23
“ti
- ’i
5
5
1
7
7
9
i>
‘X
29
30
31
7
11
(i
9
33
12
32
33
34
3.5
36
Totals
109
h‘emalr
Negro
12
10
9
13
11
16
10
18
13
23
13.5
IYhite
S,.*r,,
6
0
1
ti
4
(i
1
2
3
1
1
3
2
3
2
>
I
6
4
4
4
4
11
0
27
3;
G r a d total
328
vcrtchrae of young adults. F r o m the records, all the inale
Tvliite individuals hetwecn the ages of 25 and 36 years, iucliisive, were selected, and their cei-vical vertebrae were withdrawn. One hundred nine complete sets were found to he
available for study. Noiie displayed any gross evidence of
arthritic change in any facet, arid none slio-\vcd evitlence of
antenlortern fracture or othei. injury. Among the male Negroes, 335 similar sels mere found in the ages hetwwn 25 and
Ta4RIATIOKS I N CERVICAL VEBTERRAE
591
34 years. Female skeletons are less numerous in tlie collection, and only 27 female white sets were found. F o r the female Negro there were 57 sets. It must be remembered that
in the files all individuals with an admixture of Negro blood
were classified as Negro. Very few were of pure Negro stock,
and the term Negro-hybrid would be more accurate.
I n conipiling the tables of size, I used the first 100 sets for
the males of each stock, but for the females all available sets
were used. An occasional vertebra had suffered postmortem
damage, making it impossible to make certain measurements.
The exceptions are indicated in the tables as they occur.
METHOD
Each bone was carefully inspected and any gross anatoniical
variations were noted. The angle of inclination of each articular facet was observed, and those with marked variation were
recorded. The same procedure was carried out with the angle
that the articular facet made with the sagittal plane. Finally,
the following measurements were made with a sliding caliper :
f o r each facet the greatest diameter (anteroposterior diameter) in a plane parallel with the sagittal plane, and the greatest
diameter (lateral diameter) in a plane parallel with the coronal plane. In each case the measurement was to the nearest
millimeter .
OBSERVATIONS
There were t h e e male white individuals (no. 445, no. 584,
and 110.1075) in whom the second and third cervical vertebrae
were firmly united not only in the area of the centra, bat also
in that of the pedicles, laminae, and spinous and articular
processes. There mas no evidence that this fusion was due to
arthritic change o r to injury; therefore, it must he regarded
as being congenital in origin. There was no abnormal fusion in
any area of any other vertebra of this group. In one case (no.
301) the centruni of tlie third cervical vertebra was incompletely separated into two lateral halves by a partial defect in
the sagittal plane. This centrum was about half as tliicli as
592
CARL C. FBBNCIS
the centra of adjacent vertebrae, but the canals for the fourth
cervical nerves did not appear to have been encroached upon.
This condition has been called a "butterfly" vertebra by
roentgenologists. I n two male white skeletons (no. 301 and
no. 307) the spirious processes of the fifth cervical vertebra
were not fused, leaving a congenital midline cleft between the
two halves, and the same defect was present in the sixth vertebra of no. 317. I n no. 301, the lamina arid spinous process
of the fourth vertebra w-cre presumably congenitally absent
on the right side.
Acmoiig the male Negroes, in three cases (no. 1474, no. 3231,
and no. 2518) tlic posterior central portion of the arch of tlie
atlas was missing, and this did not appear t o be due to injury or damage. No other marked congenital variations were
seen. One individual (no. 1493) had a fusion of the fifth, sixth,
and sez-cnth vertebrae, and another (no. 2476) had a fusion of
the centra of the fifth and sixth vertebrae. I n both these
spines there was evidcnce of extensive chronic disease.
Among the €emale whitc specimens, no. 514 displayed an
absence of the posterior central portion of the arch of the
atlas, and the same condition was seen in no. 2718 of the female Segroes.
The angle of inclination of the articular facets showed very
little rariation between right and left sides, vcry few having
a difference of its much as 5". Among tlie male 15-hite the
greatest difference, approximately lo", was observed once in
the lower facets of the third vertebra and once in the lower
facets of the fourth and of the fifth vertebra. hn01lg' the male
Negroes there was one case in the upper facets of the fifth
vertebra in which a difference of 10" occurred, and the same
difference mas seen once in the lower facets of the fifth vertebra and once in the upper facets of the sixth. Among the females, variations in the angle of inclination were negligible.
There was more variability in the angle made by the articular facets with the sagittal plane. Almong the male whites in
the inferior facets of the second vertebra there were four
spcciinens with a difference of 30" and nine with 10". I n the
VARIATIONS I N CERVICAL VERTEBRAE
593
upper facets of the third vertebra there were two with a difference of 20" and 15 with 10" ; in the lower facets there was
one with 20" and one with 10". I n the upper facets of the
fourth vertebra there was one case of 20" and four cases of
10". I n the fifth vertebra there were three examples of a difference of 10" i n the upper facets and one example of 15" in
the lower. I n the upper facets of the sixth there was one of
20" and three of lo", and in the lower facets one of 10". The
articular facets involved in the joints between the second and
third cervical vertebrae of the male whites displayed more
cases with considerable variability in this angle than the facets
involved in auy other of the cervical joints. Among the male
Negroes in the lower facets of the axis there were 10 specimens
with a difference of 10" and three with a difference of 20". I n
the upper facets of the third vertebra there were six with a
difference of 10" and one with the same difference in the lower
facets. I n the lower facets of the fifth vertebra there was one
case with a difference of 30". I n the lower facets of the fifth
vertebra and in the corresponding upper facets of the sixth
there was one case with a difference of 55", which ~ v a sthe
greatest variation seen in any vertebra of any of the four
groups. Among the female whites there was one case of a
difference of 10" in the lower facets of the axis, and one of the
same difference in the upper facets of the seventh vertebra.
Among the female Negroes there was one with a difference of
20" in the lower facets of the axis.
The upper articular facets of the atlas were quite variable
in shape. The outline might be ovoid, reniform, o r dumbbell
in shape, and a few facets were divided into completely separate anterior and posterior portions. 111 measuring, these
variations were ignored and only the greatest anteroposterior
and lateral dimensions were recorded.
I n most white male specimens differences in the average
dimensions between the right and left facets a r e small (table
2). It is interesting to note that in the upper facets the average anteroposterior diameter of the right side is equal to or
greater than that of the left in every cervical vertebra with
Firut
8econcl
Third
Fourth
Fifth
Sixth
Sevcnih
Lowar fmct
First
Second
Third
Fourth
Fifth
Bixtli
Berenth
upper facet
Right
17.8 rt 1.6
11.0 rt 1.7
11.3 2 1.7
10.9 rt 1.6
10.8 2 1.6
30.7 k 1.6
13.2 2 2.5
23.2 2 2.6
18.8 2 1.6
11.4 +- 1.6
11.6 2 1.6
11.1 2 1.5
10.7 rt 1.5
10.5 rt 1.7
Mean
(i-20
14-22
8-18
8-17
7-15
7-17
8-15
17-31
15-23
8-16
9-1 7
8-16
7-1 5
8-1 6
Range
Left
17.3 f 1.5
11.3 2 1.5
11.5 rt 1.9
31.3 f 1.5
11.0 f 1.5
10.8 f 1.4
12.9 f 2.4
23.6 k 2.5
18.7 k 1.5
11.2 2 1.3
11.3 f 1.4
11.1 k 1.6
10.4 rt 1.7
9.8 zk 1.3
Menn
ANTEBOWSTIORIOR DlAMmTIER
14-21
9-16:
8-18
8-18
8-16
7-15
7-10
18-30
15-23
8-16
8-16
8-16
8-15
7-13
Range
All figures in miWetcra
Right
17.3 f 1.3
11.9 & 1.4
12.0 f 1.5
12.5 f 1.5
12.8 f 1.8
13.3 f 2.0
13.9 rt 2.5
13.4 f 1.3
16.7 f 1.6
12.0 f 1.5
12.4 f 1.5
12.6 rt 1.4
12.8 zk 1.7
13.6 f 2.2
Mean
9-17
8-18
8-21
9-16
15-22
9-lG
9-16
10-16
14-22
9-16
9-16
9-1 7
9-1 6
9-1 8
KHllKr
Left
12.1 f 1.5
12.6 k 1.5
12.9 f 1.6
13.2 2 1.6
13.5 rt 2.0
15.0 rt 2.6
17.0 P 1.6
11.8 f 1.3
18.3 f 1.7
12.0 f 1.4
12.4 f 1.6
12.7 f 1.5
13.1 f 1.8
13.6 k 1.9
Mean
IAATBUALUIAXETRR
Average dimmxions of artieiikr faaats of cervical Prartebrac ( n n k wkite)
TABLE 2
14-23
9-17
10-16
9-17
9-17
9-18
9-23
10-16
15-23
9-16
9-16
9-16
8-18
9-17
Hsnge
8
k
0
VARIATIOKS I N CERVICAL VERTEBRAE
595
the exception of tlie atlas, whereas in the lower facets the
findings a r e reversed. The lateral diameter of both upper and
lower facets on the left side is equal to or greater than that of
the i-ight side in every instance except i n the lower facets of
the atlas. The most marked differences occur i n the lateral
diameter of the upper facets of the axis, in the anteroposterior
diameter of the upper facets of the seventh vertebra, and in
hotli diameters of the lower facets of the same bone. The
articular facets involved in the articulations between the fifth
and sixth vertebrae, that is, the upper facets of six and the
lower of five, show slightly more diff ercnce between riglit and
left than do the others when all four areas a r e considered together.
In table 3 (malc white) the distribution of the actual difference in length of the respective diameters of the right and
left sides is tabulated. I n each vertebra there a r e a few showing coiisiderahle difference, hut with the exception of the
serentli no single vertebra can be singled out as being more
variable than any other. Inspection of the vertebrae shows
that adjacent facets tend to be similar i n size. F o r example,
if tlic lower right facet of a given vertebra is large the corresponding upper facet of the vertebra below also is large.
For the male Negro, female white, and female Negro groups,
tables showing the actual distribution of differences in length
were compiled but have not been included for publication because in each group the seventh vertebra was the only one
that sho~vedany marked variability, and the findings were in
all groups essentially the same as for the malc white.
h m o n g male Negro specimens, differences between the riglit
and left facets a r e small (table 4) ; the lateral diameter of the
lower facets of the atlas shows the greatest difference. Thc
articular facets involved i n the articulation between the second and Ihird vertebrae, that is, between the lower facets of
the axis and the upper of the third vertebra, show slightly
more difference between right and left sides when all four
areas a r e considered together. There is no noteworthy tliffere w e in size of the cervical vertebra in white and Negro.
596
CARL C. FRANCIS
TABLE 3
Distribution of variation in diameters of right and l e f t articular facets
of t k e cervical vertebrae (male white)
( I n millimeters of differmce)
ANTEROPOSTERIOR DIAMETER
0
1
2
3
4
5
4
6
7
2
1
1
8
9 1 0
~
U p p e r facet
First
secolla
Third
Fourth
Fifth
Sixth
Seventh
23
30
38
39
41
34
27
40
43
39
42
38
41
37
15
17
15
12
15
17
21
11
8
4
5
5
5
11
7
2
2
1
1
3
2
Lower facet
First
Second
Third
Fourth
Fifth
Sixth
Sevrn th
21
28
29
26
37
29
17
50
37
41
41
34
38
25
19
23
18
23
18
21
16
7
7
5
5
7
9
16
3
2
4
3
1
3
13
1.pper facet
First
Second
Third
Fourth
Fifth
Sixth
Seventh
35
14
31
33
33
30
23
41
36
43
46
40
33
35
12
22
21
18
18
21
21
8
11
4
4
7
1
1
3
8
6
38
27
35
31
21
20
20
32
50
34
38
36
39
28
20
19
16
23
24
22
27
6
5
14
__
2
1
2
1
1
1
2
2
1
6
4
7
3
3
2
1
2
Lorcer facpt
First
Second
Third
Fourth
Fifth
Sixth
Seventh
8
1
10
7
7
6
13
2
1
3
1
2
1
6
6
1
1
1
1
1
2
1
1
1
First
Second
Third
Fourth
Fif t Ii
Sistli
Seveiitli
Lower facet
First
second
Third
Fourth
Fifth
Sixth
Seve11th
U p p e r facet
Right
78.4 t 1.4
12.0 ir 1.7
17.7 t 1.5
11.8 _t 1.5
11.5 zk 1.6
11.2 t 1.7
12.3 I- 2.7
23.6 t 2.5
19.0 -I- 1.3
11.2 t 1.5
11.5 t 1.3
11.3 & 1.4
11.0 t 1.4
10.1 -C 1.3
Alean
16-22
9-16
6-15
8-15
8-16
8-15
6-18
39-28
16-22
8-15
8-14
8-15
8-14
8-13
Range
Left
18.3 I- 1.3
11.4 -C 1.8
11.6 & 1.6
11.5 +- 1.5
11.5 & 1.5
11.3 t 1.7
12.2 t 2.2
23.2 _t 2.8
18.9 & 1.5
11.5 & 1.6
11.7 & 1.5
11.4 -C 1.4
11.1 t 1.6
10.2 t 1.3
Mean
ANTEROPOSTEKIOR DIAMETER
15-22
8-16
8-15
6-16
8-16
8-16
8-18
16-26
16-22
6-16
8-15
8-15
8-15
6-13
Range
Right
17.6 i:1.5
11.3 t 1.6
11.9 ir 1.5
12.5 2 1.5
13.2 zk 1.7
13.5 2 1.8
14.9 -c 2.8
11.5 _i 1.2
17.7 & 1.4
11.9 rt 1.5
12.2 2 1.4
12.6 -C 1.6
13.3 2 1.7
14.4 t 1.9
______
Mean
14-21
8-15
9-15
9-16
9-17
10-17
10-20
9-15
15-21
8-15
9-15
8-16
10-17
10-2 0
Range
Left
16.7 t 1.3
11.8 & 1.4
12.1 I- 1.3
12.9 -C 1.4
13.4 t 1.5
14.0 t 2.0
15.1 +- 2.6
11.6 F 1.3
17.9 ir 1.4
11.4 1
.1.4
11.8 t 1.4
12.3 t 1.4
13.3 t 1.7
14.4 t 1.9
Mean
LATERAL DIAMETER
Average dinicnsions of articular facets of cervical vertebrae (male Negro)
All figures i n millimeters
TABLK 4
14-20
9-15
9-16
10-17
10-17
10-18
9-20
10-15
15-21
9-14
8-15
9-15
9-17
10-19
Range
First
Sec,ond
Third
Foartli
Fif tll
Sixth
Seventh
Lower f aeet
FirRt
sccoild
Third
Fourth
Pif th
Sixth
Scvciith
upper facct
16.6 f 1.3
11.6 2 1.3
11.7 f 1.6
11.0 f 1.2
11.3 f 1.3
12.0 f 2.1
13.3 f 2.2
15-20
9-14
9-15
10-14
9-14
8-15
8-1 8
19-24
14-20
8-12
8-13
9-12
8-12
8-1 2
Range
Left
17.2 f 1.3
11.1 f 1.4
11.1 f 1.9
10.7 f 1.3
10.5 f 1.4
10.7 f 1.5
11.8 f2.7
21.6 -t- 2.1
17.4 f 1.4
11.0 2 1.5
11.2 k 1.3
10.7 f 1.3
10.2 f 1.3
11.3 2 1.7
Mean
A,YTEROP0STERIOB DIAXETEIL
Right
21.8 f 1.5
18.0 f 1.8
10.4 f 1.1
11.0 f 1.2
10.4 f 1.0
10.3 f 1.2
9.9 f 1.0
Mean
-
16-20
9-14
8-1 7
8-14
s-I 4
8-15
7-1 7
17-26
14-20
9-1 (I
8-13
9-13
8-13
8-14
Range
Right
16.2 f 1.3
10.7 & 1.1
11.1 f 1.1
11.1 f 1.1
11.9 f 1.6
12.5 2 1.6
12.4 f 1.8
12.4 f 1.4
15.1 f 1.3
11.3 2 1.3
11.4 & 1.1
11.5 & 1.1
12.2 f 1.2
13.3 f 2.0
Mean
13-18
9-13
9-13
9-13
9-14
9-15
10-15
10-15
13-18
9-14
9-13
10-13
10-14
9-17
Bange
Left
14.9 f 1.2
11.4 f 1.2
11.6 f 1.3
11.9 f 1.3
12.4 f 1.5
13.0 2 1.7
14.3 f 1.G
12.0 f 1.3
16.7 f 1.7
11.4 f 1.6
11.2 f 1.1
11.4 f 1.1
12.1 f 1.4
13.4 & 1.9
Mean
IATDEAL DIAMETER
Average di.me~t.sionsof articular facets of oervieal vrrtebrac (female white)
All figures in millimeters
TABLE 5
12-18
10-15
10-15
9-15
8-15
10-1 G
11-17
9-15
12-20
9-16
9-1 3
8-1 3
9-15
9-10
Range
11.2 r 1.1
11.2 i 1 . 3
11.1 2 1.4
11.2 t 1.3
11.2 2 1.5
12.3 2 2.5
1i.6: t l . 6
21.9 & 2.1
li.6 t 1.3
10.6: t 1.2"
10.9 3- 1.2'
10.6: & 1.0
10.5 t 1.1
10.1 t 1.4-
Bascd on 56 cases.
First
Second
Third
Fourth
Fifth
Sixth
Sevellth
Lowrv facr t
First
Secoll tl
Third
Fourth
Fifth
Sixth
Rcvrn th
rppcr fna t
Jkllll
14-22
9-13
9-15
9-14
9-14
9-15
10-17
17-26
15-20
9-13
9-14
9-13
9-13
7-13
Kange
-
17.8 +- 1.4
11.0 i 1.2
11.2 1 1 . 5
10.8 t 1.1*
10.7 t 1.3
10.8 I
1.4
11.6 t 1.9"
22.0 i- 2.5
17.7 ? 1.5
10.8 t 1.1"
11.2 +- 1.0"
11.1 t 1.0
10.6 t 1.1
9.9 t 1.5'
15-21
9-14
9-15
9-13
9-14
9-14
10-15
17-28
15-21
9-13
9-14
9-13
9-13
8-14
Range
1S.6 C 1.6
10.7 t 1.1
11.0 t 1.1
11.5 t 1.5"
12.1 i 1.3
12.6: t 1.8
12.4 & 2.1
11.1 C 1.4
15.7 & 1.1
11.0 i 1.2*
11.3 t 1.3"
11.4 2 1 . 4
12.3 & 1.2
13.4 -C 1.8"
__-_____-
Right
Mean
inillimeters
___.___
Left
iii
Mean
ANTEROYOSTERIOR DIAMETER
Right
~
All figures
13 19
9-14
9-14
9-15
10-13
9-17
9-17
8-15
14-18
9-13
9-14
9-14
9-14
9-17
Rdngr
LPft
~
15.1 C 1.2
11.1& 1.1
11.3 ? 1.2
11.7 i 1.3*
12.4 2 1.5
13.3 +- 1.7
13.3 +- 2.0
11.2 i 1.4
16.1 & 1.4
10.8 t 1.1'
10.8 2 1.2"
11.2 I
1.2
12.4 t 1.3
13.5 t 1.4"
Mean
_
I A T K R A L 1)IAXIITIIR
Avrragc ilbin('nsions of ariac!rlnr faccts of ccreicnl v w t r h r n r (frninlc S r g r o )
_
13-18
9-13
9-14
9-14
9-15
9-17
9-19
8-15
13-19
9-13
9-13
9-13
10-15
9-17
Range
_
600
CARL C. FRA4NCIS
I n female white specimeiis there is a tendency f o r somewhat
greater variation between comparable measurements of right
anci left sides (table 5). The unusually large figures for the
anteroposterior diameter of the left upper facet of the seventh
ancl o l thp right lower facets of the sixth ancl seventh verteTABTJE 7
1111)iot.sions of aiticirlai facets of Atlaiitorlmitol articulation
White
Mean
Xea1.o
Range
~
~
_______
__-
Mean
-
__
Range
-_-
D i a ~ n c t c iof
f a c e t s on atlas
Vertical
L at ern1
9.7 i- 1.6
10.2 -t 1.6
Diameter of
facets on dens
Vertical
10.6 i 1.9
Tlateral
8.7 ? 1.3
_
_ ~ _ _~
______
6-13
6-15
9.7 -t 1.8
10.4 t 1.3
7-11
8-1 3
6-16
6-14
11.3 ? 1.9
9.0 t 1.1
8-li
7-12
FBBIALE
White
Negro
_________
D~unwterof
facets on atlas
Vertical
Lateral
.___
Range
Mean
Ranpr
9.4 t 1.4
9.9 t 1.6
7-12
7-13
9.6 -t 1.4
10.3 "r 1.2
7-12
8-12
10.3 ? 1.7
8.2 t 1.0
8-14
6-10
11.1 t 2.1
8.8 & 1.0
7-15
6-10
Vean
Din meter of
furets on dens
Vertical
Lateral
brae are probably due to the small number of cases. I t is interesting to note that the lateral diameter of the left upper
facet of the axis is mach longer than that of the left. This was
also observed in the inale white anci was not seen in either
Negro group.
Among fernale Negro specimens there is littlc variation in
dimensions of the right ancl left facets with the exception of
VARIATIONS I S CERVICAL VERTEBRAE
601
the lower ones of the seventh vertebra (table 6). When the
four facets involved in the articulation between any two vertebrae are considered together, the joint between the fifth and
sixth is slightly more variable than the others.
Measurements of the articular facets of the joint between
the dens and the atlas for all four groups are given in table 7
f o r the sake of completeness.
DISCUSSION
Standard texts state that occasionally the second and third
cervical vertebrae may be fused congenitally, and this was
seen in the male white group but not in the others. Such fusion
would, of course, preclude any movement, and Cave ('37) has
postulated that such fusion is an attempt to guarantee increased stability of the cranio-cervical area.
Within a single vertebra, the failure of fusion of the posterior portions (cervical spina bifida) might make the area
somemhat less stable, and the absence of one lamina and of its
corresponding half of the spinous process would tend toward
instability. I n the male white group this would indicate that
the articulations associated with the fifth vertebra would be
the most likely to give evidence of instability, but one would
not be warranted in drawing any general conclusion from this
single group, particularly since the condition was not observed
in any of the other groups.
I n general the Negro cervical vertebrae showed less tendency to display congenital anomalies than did the white.
With regard to instability of an intervertebral joint, variations in the angle of inclination of the articular facets ~7ould
appear to be of greater significance than variations in the
angle with the sagittal plane. Differences in the angle of inclination are minor, and no joint is more subject to variation
than any other. However, in the articulations between the second and third vertebrae of both male groups there was somewhat more variability in the angle with the sagittal plane.
Usually this difference is not great, and I did not find the
602
C A R L C. F R A N C I S
extreme differences reported by Overtori and Grossrnaii except in one instance between thp fifth and sixth vertebrae.
When one uses differences in size of right and left articular
facets as a criterion of variability of the apophyseal joints,
those between the fifth arid sixth cervical vertebrae display a
little more variability in the male white group and in the female Negro group. This was the finding between the second
and third vertebrae in the male Negro group. I-Io\~ever,no
joint was outstandingly variable.
HUMNARY ANT, C’ONCLUSIOSS
The cervical vertebrae of 328 individuals betwecn the ages
of 25 and 36 years, inclusive, were examiucd and ccrtaiii
~neasu~ernents
were made. Variations in the angle of inclination of the articular facets and in the aiiglc with the sagittal
plane were considered. Tables of dimensions of the articular
facets are given f o r 100 male white and 100 Amale Xegro individuals, and f o r 27 fcmale white and 57 female Negro.
There is no evidence from this study that any one of the
cervical vertebrae is subject t o congenital variations which
mould make the apophyseal articulations particularly unstable, o r that any is outstandingly variable.
L[TERATUBE CITED
(‘AVE,
1937 The rertchra eritica. J . Aiiat., L o i d o n , 7 2 : 319.
1952 Anatomical variations in thr. aIticiilations between the secorid niid third rervical vertebrae. J . Eone and
Joint Surg., S i - A : 155-1 61.
A . 1 . E.
OTERTOX, T,. M., AND J . W. GROSSM4N
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