Page 103 - My FlipBook
P. 103
8
BONES. 113
of a cylindroid joint. The axis of rotation is perpendicular to the axis
of the moving bone, or, as in the case of the elbow, the axis of two
bones, the radius and ulna, since both of these describe curvations
around the axis of rotation. The paths of movement of the hinge-
joint are free within certain limits. These degrees of freedom are of
necessity fixed by the direction of the greatest convexity. The co-opera-
tion of the surfaces is exact."
In man the temporo-maxillary articulation presents a combination
of these movements. In the Carnivora, however, this joint has no
gliding movement, as the condyle is a half cylinder working in a deep
glenoid fossa of corresponding form, which only allows an up-and-down
or hinge movement. In ruminants the condyles of the inferior maxillse
are only slightly convex, and the glenoid fossae of the temporal bones
but slightly concave. This arrangement allows great latitude of motion,
and the joint is a combination of the arthrodial and of the hinge, as it
likewise is in man.
The gliding movement of this joint in man, characteristic of the
arthrodial articulation, has an important bearing in the adjustment of
artificial teeth. If the condyles of the inferior maxilla are carried
well up into the glenoid fossae when the mouth is closed, the jaws or
their teeth will be in proper apposition to each other.
The structures connected with the temporo-maxillary articulation are
generally described as five ligaments and two synovial sacs. The liga-
FxG. 58.
Temporo-maxillary Articulation, internal view.
ments are the capsular, external and internal lateral, stylo-maxillary,
and an interarticular fibro-cartilage. The capsular and external lateral
will be described as one ligament, while the internal lateral and stylo-
VoL. I.—
BONES. 113
of a cylindroid joint. The axis of rotation is perpendicular to the axis
of the moving bone, or, as in the case of the elbow, the axis of two
bones, the radius and ulna, since both of these describe curvations
around the axis of rotation. The paths of movement of the hinge-
joint are free within certain limits. These degrees of freedom are of
necessity fixed by the direction of the greatest convexity. The co-opera-
tion of the surfaces is exact."
In man the temporo-maxillary articulation presents a combination
of these movements. In the Carnivora, however, this joint has no
gliding movement, as the condyle is a half cylinder working in a deep
glenoid fossa of corresponding form, which only allows an up-and-down
or hinge movement. In ruminants the condyles of the inferior maxillse
are only slightly convex, and the glenoid fossae of the temporal bones
but slightly concave. This arrangement allows great latitude of motion,
and the joint is a combination of the arthrodial and of the hinge, as it
likewise is in man.
The gliding movement of this joint in man, characteristic of the
arthrodial articulation, has an important bearing in the adjustment of
artificial teeth. If the condyles of the inferior maxilla are carried
well up into the glenoid fossae when the mouth is closed, the jaws or
their teeth will be in proper apposition to each other.
The structures connected with the temporo-maxillary articulation are
generally described as five ligaments and two synovial sacs. The liga-
FxG. 58.
Temporo-maxillary Articulation, internal view.
ments are the capsular, external and internal lateral, stylo-maxillary,
and an interarticular fibro-cartilage. The capsular and external lateral
will be described as one ligament, while the internal lateral and stylo-
VoL. I.—
