Download osteological investigations upon the external surface of temporal

Bulgarian Journal of Veterinary Medicine (2006), 9, No 4, 251−255
OSTEOLOGICAL INVESTIGATIONS UPON THE
EXTERNAL SURFACE OF TEMPORAL FOSSA IN DOGS
FROM VARIOUS BREEDS AND CROSSBRED DOGS
G. KOSTADINOV, A. DECHEV & A. VODENICHAROV
Department of Veterinary Anatomy, Histology and Embryology, Faculty of
Veterinary Medicine, Trakia University, Stara Zagora, Bulgaria
Summary
Kostadinov, G., A. Dechev & A. Vodenicharov, 2006. Osteological investigations upon the
external surface of temporal fossa in dogs from various breeds and crossbred dogs. Bulg. J.
Vet. Med., 9, No 4, 251−255.
The external surface of temporal fossa was investigated in 28 canine skulls − 22 of purebred dogs
and 6 of dogs of unidentified breed. It was found out that the external surface of temporal fossa in
dogs of unidentified breed was smooth whereas in purebred individuals it had a various degree of
roughness. In Pitbulls, the surface was slightly uneven, with short, rostroventrally directed crests. The
best shaped outer surface of temporal fossa was most clearly manifested in the French Bulldog. The
temporal fossa was the most prominent in the Dachshund and in Miniature Pinschers, fairly prominent in the Collie, the Labrador and German Shepherds and the least prominent in the Caucasian
Ovcharka and the Shar Planinets. The obtained data allowed to assume that the external surface and
the prominence of the temporal fossa could be important for further studies upon the determination of
the strength of the temporal muscle and its role in the function of mandible and bite strength.
Key words: bone relief, dog breeds, skull, temporal fossa
INTRODUCTION
It is known that the external surface of
temporal fossa together with the external
sagittal crest and the temporal crest serve
as attachment points of the temporal muscle. The latter is the strongest masticatory
muscle that is supposed to be the most
involved in canine biting force and the
function of the mandible (Dyce et al.,
1987; Miller, 1993; Frewein, 1994).
Most literature data are about the
mandibular joint and masticatory muscles
in dogs as a whole, without details related
to type or breed (Strom et al., 1988; Constantinescu, 2002). Moreover, the data
about the sites of attachment of the temporalis muscle and the external surface of
temporal fossa are few and contradictory
(Sisson, 1975; Frewein, 1994; Evans & de
Lahunta, 1996). The crests observed on
the external surface of both parietal bones,
the heights of the external sagittal crest
and the temporal crest in different canine
types and breeds are also interesting
(Lignereux et al., 1991; Regedon et al.,
1991; Onar, 1999; Onar, 2001; Dechev et
al., 2004; Karan et al., 2006).
The studies of Endo et al. (1999) on
wolf’s head show that the temporal muscle
does not occupy the lateral surface of the
frontal bone as is in domesticated dogs,
but its thickness was higher. The authors
suppose that during the domestication of
Osteological investigations upon the external surface of temporal fossa in dogs from various...
the dog, the three-dimensional plan of the
temporalis muscle had changed, manifested by shifting of attachment surface in
the frontal bone and decreased thickness
of muscle body due to increased brain
size.
The purpose of the present study was
to perform a comparative characteristics
of attachment sites of the temporal muscle
on canine skull and in particular, to describe the external surface of the temporal
fossa with regard to elucidation of the role
of this muscle in the function of mandibular joint and bite strength in the different
breeds.
MATERIALS AND METHODS
The studies were performed on 28 skulls
from adult dogs (12 male and 16 female at
the age of 4−11 years) as followed: 4
Miniature Pinschers, 1 Dachshund, 1 Poodle, 1 Drathaar, 1 Collie, 2 German
Shepherds, 1 Caucasian Ovcharka, 1 Belgian Sheepdog, 1 Labrador, 3 Dogues, 1
Shar Planinets, 1 Rottweiler, 2 Pittbulls, 1
French Bulldog and 1 Saint Bernard. The
other 6 skulls were from stray dogs of
unidentified breed, obtained in the Stara
Zagora Community kennel.
All skulls were taken from dead or
euthanized dogs. After skin removal, they
were soaked for several hours in running
water. Afterwards, the heads were boiled
in water, the soft tissues were removed
and the skulls dried at room temperature.
Then they were defatted in an ether/ chloroform mixture (1:1) and bleached in 4%
hydrogen peroxide solution for 24 hours.
Osteoscopy of the external surface of
temporal fossa and the prominence of the
parietal bone, the length and the height of
the external sagittal crest at the parietal
vault was performed in all skulls. The two
temporal lines and the mode of their sepa-
252
ration from the external sagittal crest were
followed out.
RESULTS AND DISCUSSION
The results of osteoscopy revealed that in
the various canine breeds, there were differences in the shape, size and depth of
temporal fossa.
In Caucasian Ovcharka and Shar
Planinets breeds, belonging to the dolichocephalic type, the temporal fossa had a
rectangular shape with clearly shaped
crest on its surface, oriented obliquely and
longitudinally. The parietal bone was
slightly prominent, thus making the temporal fossa deeper (Fig. 1 and Fig. 2).
Temporal fossa
Fig. 1. Skull of Caucasian Ovcharka. The temporal fossa is with a rectangular shape and
low, obliquely oriented lines; bar=25 mm.
Fig. 2. Shar Planinetz skull. A rectangular temporal fossa and single low lines (arrows), oriented predominantly longitudinally; bar=24 mm.
BJVM, 9, No 4
G. Kostadinov, A. Dechev & A. Vodenicharov
Fig. 3. Saint-Bernard skull and atlas. Deep temporal fossa, limited by prominent external sagittal and temporal crests (arrows); bar=28 mm.
Fig. 4. Pitbull skull. Triangular temporal fossa,
clearly defined by prominent external and
temporal crests; bar=19 mm.
In the Saint Bernard, the temporal
fossa was relatively deep, with irregular
surface and noticeably shaped thickenings
in the caudoventral edge. The caudal edge
of the external sagittal crest was high,
with enlarged dorsal edge (Fig. 3).
In Pittbulls, the temporal fossa was
with a triangular shape, apparent rough
surface and crests directed caudodorsally.
The external sagittal crest and the temporal crest were clearly shaped (Fig. 4).
The temporal fossa in the French
Bulldog was trapezoid-shaped. The central parts of parietal bones were convex.
BJVM, 9, No 4
Their surface was rough with well-formed
bone thickenings, especially in their dorsal half. The temporal crest and the temporal line were rounded. The external
sagittal crest was indistinct and located in
the area of the interparietal bone (Fig. 5).
The parietal bones were highly prominent in the Dachshund, Miniature Pinschers and the Poodle and consequently,
the temporal fossa in these breeds was
shallow. The external sagittal crest was
indistinct in Miniature Pinscher and Poodle breeds and its initial part − well shaped in the Dachshund. It must be stated
that the temporal lines in these breeds were
independent and at a various distance from
the median line. They were the most closely
located in the Dachshund and the most outlying – in Miniature Pinschers. In these
cases, a shaped parietal field was observed
on the calvarium (Fig. 6 and Fig. 7).
The temporal fossa of skulls of
Dogues was with an irregular trapezoid
shape. Parietal bones had low crests, part
of them oriented longitudinally and the
other – almost vertically. They formed a
quadrangular field with a rough surface,
situated in the caudodorsal edge of the
temporal fossa. The external sagittal crest
and the temporal crest were relatively high
and sharp-edged.
Fig. 5. French Bulldog skull. Trapezoidal temporal fossa with an irregular surface; bar=18
mm.
253
Osteological investigations upon the external surface of temporal fossa in dogs from various...
*
Fig. 6. Dachshund skull. A well-defined initial part of the external sagittal crest, that is
anteriorly situated between independently
differentiated temporal lines (arrows); bar=16
mm.
Fig. 7. Miniature Pintscher skull. The punctated line shows the external sagittal crest on
the dorsal surface of the skull; bar=13 mm.
Fig. 8. Skull of a dog of an unidentified breed
(stray dog). Low crests, prominent and
smooth external surface of the temporal fossa;
bar=17 mm.
254
In the skulls of dogs from unknown
breeds, the surface of temporal fossa was
almost smooth. The cranial parts of the
external sagittal crest and the temporal
crest were low (Fig. 8).
The performed osteoscopic investigations allowed to conclude that in dolichocephalic dogs, the temporal fossa was
commonly with a rectangular or irregular
trapezoidal shape, considerable depth and
with marked rough surface. The external
saguttal crest was high. In brachicephalic
dogs, the temporal fossa was with predominantly triangular or trapezoidal shape. The parietal bones were prominent
and smooth and consequently, the temproal fossa was shallow.
The present study attempted to make a
comparative evaluation of the types of
attachment sites of the temporal muscle to
the canine skull. Although the number of
included skulls is low, the data revealed a
number of significant differences between
the different types. The crests and thickenings on the surface of parietal bones allowed us to assume that they serve for the
attachment of well shaped muscle layers,
oriented in various directions. On the
other side, the strong prominence of the
external sagittal crest in some breeds allowed the attachment of muscle bunches
under a bigger angle that would increased
the coefficient of efficiency of the muscle.
The obtained results, although from a
relatively few individuals, permitted us to
suppose that the outer surface and the
prominences of the temporal fossa, together with the other attachment sites of
temporal muscle on the skull could be
important for the bite strength and the
function of the mandibular joint. Most
evidently, additional morpho-functional
studies are necessary for further elucidation of this subject.
BJVM, 9, No 4
G. Kostadinov, A. Dechev & A. Vodenicharov
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Paper received 28.04.2006; accepted for
publication 14.11.2006
Correspondence:
G. Kostadinov,
Department of Veterinary Anatomy,
Histology and Embryology,
Faculty of Veterinary Medicine,
Trakia University, Student’s Campus
6000 Stara Zagora, Bulgaria.
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