The complete works of John Hunter, F.R.S (Volume 2).

  • Hunter, John, 1728-1793.
Date:
1841
Catalogue details

Licence: Public Domain Mark

Credit: The complete works of John Hunter, F.R.S (Volume 2). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    moves almost directly forwards in passing from the cavity to the eminence; and the parallelism of the motion is also preserved by the shape of an intermediate cartilage. In this joint there is a moveable cartilage, which, though common to both condyle and cavity, ought to be considered rather as an appendage of the former than of the latter, being more closely con- nected with it, so as to accompany it in its motion along the'com- mon surface of both the cavity and eminence. This cartilage is nearly of the same dimensions with the condyle, which it covers, and is hollowed out on its inferior surface, to receive the condyle. On its upper surface it is more unequal, being moulded to the cavity and eminence of the articulating surface of the temporal bone, though it is considerably less, and is therefore capable of being moved with the condyle, from one part of that surface to another. Its texture is ligamento-cartilagineous. This moveable cartilage is connected with both the condyle of the jaw and the articulating surface of the temporal bone, by distinct ligaments, arising irom its edcres all round. That by which it is attached to the temporal bone fs the most free and loose ; though both ligaments will allow an easy motion 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 hVamenCwhich 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 ligament 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. Of the Motion in the Joint of the Lower Jaw. The lower jaw, from the manner of its articulation, is susceptible of a -reat many motions. The whole jaw may be brought hori- zontally forwards, by the condyles sliding from the cavity towards the eminences on each side. This motion is performed chiefly whence teeth of the lower jaw are brought directly under those of the upper, in order to bite or hold anything very fast between theOr the condyles only may be brought forwards, while the rest Of the jaw is tilted backwards, as is the case when the mouth is open -for on that occasion the angle of the jaw is tilted backwards and the chin moves downwards, and a little backwards also. In this last motion the condyle turns its face a little forwards; and he centre of motion lies a little below the condyle, in the line be- ween i and the angle of the jaw. By such an advancement of Zcondyles forwards, together with the rotation mentioned, the ape! ture of The mouth may be considerably enlarged; a circumstance