The jaw-bone, in few cases, is completely dislocated, for the zygomatic
process formed from the upper jaw-bone (malar?
) and the bone behind
the ear (temporal?
) shuts up the heads of the under jaw, being above
the one (condyloid process?
), and below the other (coronoid process?
Of these extremities of the lower jaw, the one, from its length, is
not much exposed to accidents, while the other, the coronoid, is more
prominent than the zygoma, and from both these heads nervous tendons
arise, with which the muscles called temporal and masseter are connected;
they have got these names from their actions and connections; for
in eating, speaking, and the other functional uses of the mouth, the
upper jaw is at rest, as being connected with the head by synarthrosis,
and not by diarthrosis (enarthrosis?
): but the lower jaw has motion,
for it is connected with the upper jaw and the head by enarthrosis.
Wherefore, in convulsions and tetanus, the first symptom manifested
is rigidity of the lower jaw; and the reason why wounds in the temporal
region are fatal and induce coma, will be stated in another place.
These are the reasons why complete dislocation does not readily take
place, and this is another reason, because there is seldom a necessity
for swallowing so large pieces of food as would make a man gape more
than he easily can, and dislocation could not take place in any other
position than in great gaping, by which the jaw is displaced to either
side. This circumstance, however, contributes [p. 229]
to dislocation there;
of nerves (ligaments?
) and muscles around joints, or connected with
joints, such as are frequently moved in using the member are the most
yielding to extension, in the same manner as well-dressed hides yield
the most. With regard, then, to the matter on hand, the jaw-bone is
rarely dislocated, but is frequently slackened (partially displaced?
in gaping, in the same manner as many other derangements of muscles
and tendons arise. Dislocation is particularly recognized by these
symptoms: the lower jaw protrudes forward, there is displacement to
the opposite side, the coronoid process appears more prominent than
natural on the upper jaw, and the patient cannot shut his lower jaw
but with difficulty. The mode of reduction which will apply in such
cases is obvious: one person must secure the patient's head, and another,
taking hold of the lower jaw with his fingers within and without at
the chin, while the patient gapes as much as he can, first moves the
lower jaw about for a time, pushing it to this side and that with
the hand, and directing the patient himself to relax the jaw, to move
it about, and yield as much as possible; then all of a sudden the
operator must open the mouth, while he attends at the same time to
three positions: for the lower jaw is to be moved from the place to
which it is dislocated to its natural position; it is to be pushed
backward, and along with these the jaws are to be brought together
and kept shut. This is the method of reduction, and it cannot be performed
in any other way. A short treatment suffices, a waxed compress is
to be laid on, and bound with a loose bandage. It is safer to operate
with the patient laid on his back, and his head supported on a leather
cushion well filled, so that it may yield as little as possible, but
some person must hold the patient's head.