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12 OF THE ARTICULATION OF THE LOWER-JAW.
Temporal Bone, is the most free and loose ; though both liga-
ments will allow an easy motion, or sliding of the cartilage on
the respective surfaces of the Condyle, and Temporal Bone.
These attachments of the cartilage are strengthened, and the
whole articulation secured, by an external ligament, -which is
common to both, and which is fixed to the Temporal Bone, and
to the neck of the Condyle. On the inner surface of the liga-
ment, which attaches the cartilage to the Temporal Bone, and
backwards, in the cavity, is placed what is commonly called the
Gland of the Joint ; at least, the ligament is there much more
vascular than at any other part, (v)
Weitbrecht) surround the greater portion of the joint, cover the
synovial membranes, and serve to connect the fibro-cartilage with
the osseous margins. These thin ligamentous structures are not
distinguished in the text from the synovial bursae, neither is it
usual to find the latter noticed specially in anatomical works of
the period. They had been, however, described at some length by
Weitbrecht, whose work appeared in 1742. (1) They are two in
The
number—one placed above the fibro-cartilage, the other below it.
superior is the larger and looser it lines the upper surface of the inter-
;
articular cartilage and the smooth part of the glenoid cavity. The
inferior is interposed between the condyle and the lower surface of the
fibro-cartilage. When the latter structure is perforated in the centre,
the synovial bursa) communicate and form one cavity.]
(c) [Dr Clopton Havers,(2) in 1G91, described the vascular processes of
the synovial membrane, which are commonly found projecting more
or less into the cavities of joints. When these processes are of any size,
they generally contain fat. They are frequently cleft, so as to present a
fringed appearance at their free border, which is very vascular. Dr
Havers regarded them as special structures for the secretion of synovia,
and named them the "mucilaginous glands of the joints." Subsequent
anatomists have generally denied them a special function, although, as
extensions of the synovial membrane, they must necessarily increase the
amount of secretion. Havers's view was revived by Mr Rainey, in a
paper published in the Proceedings of the Royal Society, in 1846. He
bases his advocacy on the constant occurrence of such vascular processes,
not only in the joints, but also in synovial sheaths, on a peculiar convo-
luted condition of their blood-vessels, and on the arrangement of the
epithelium covering them, which, " besides enclosing separately each
(1) Syndesmologia, p. 80, 1742.
(2.) Ostcologia Nova, p. 187, 1G91.