of the nose, and may sometimes be relieved by pressing or cutting the
nerve, where it passes into the bone of the orbit above the eye. When it
affects a small defined part on the parietal bone on one side, it is
generally termed Clavus hystericus, and is always I believe owing to a
diseased dens molaris. The tendons of the muscles, which serve the office
of mastication, have been extended into pain at the same time, that the
membranous coverings of the roots of the teeth have been compressed into
pain, during the biting or mastication of hard bodies. Hence when the
membranes, which cover the roots of the teeth, become affected with pain by
a beginning decay, or perhaps by the torpor or coldness of the dying part
of the tooth, the tendons and membranous fascia of the muscles about the
same side of the head become affected with violent pain by their sensitive
associations: and as soon as this associated pain takes place, the pain of
the tooth entirely ceases, as explained in the second species of this
genus.

A remarkable circumstance attends this kind of hemicrania, viz. that it
recurs by periods like those of intermittent fevers, as explained in the
Section on Catenation of Motions; these periods sometimes correspond with
alternate lunar or solar days like tertian agues, and that even when a
decaying tooth is evidently the cause; which has been evinced by the cure
of the disease by extracting the tooth. At other times they observe the
monthly lunations, and seem to be induced by the debility, which attends
menstruation.

The dens sapientiae, or last tooth of the upper jaw, frequently decays
first, and gives hemicrania over the eye on the same side. The first or
second grinder in the under-jaw is liable to give violent pain about the
middle of the parietal bone, or side of the head, on the same side, which
is generally called the Clavus hystericus, of which an instructive case is
related in Sect. XXXV. 2. 1.

M. M. Detect and extract the diseased tooth. Cut the affected nerve, or
stimulate the diseased membrane by acu-puncture. Venesection to six ounces
by the lancet or by leeches. A strong emetic and a subsequent cathartic;
and then an opiate and the bark. Pass small electric shocks through the
pained membrane, and through the teeth on the same side. Apply vitriolic
ether externally, and a grain of opium with camphor internally, to the
cheek on the affected side, where a diseased tooth may be suspected. Foment
the h