(From the same). A fissure or crack. The mouth, or other natural apertures into the body, are called fissures; but morbid fissures are cracks in the skull, or in a long bone when the fracture is longitudinal.

A morbid fissure differs from a fracture, because in the latter there is a total solution of continuity. A fracture also is transverse or oblique; a fissure longitudinal.

Fissures most frequently occur in the skull; and of these there is, first, the counter fissure, when the blow is received on one side of the head, and the fissure is on the other; where the internal table is broken, the external remaining sound; or where the stroke is received on one bone, and the fissure is in that adjoining. Many authors doubt the existence of a counter fissure, and it is difficultly accounted for; but the facts are well attested. Hippocrates, Galen, Celsus, Berengarius, Fal-lopius, and several others, assert their having met with such instances. The most frequent kind is that which is soon discovered by laying the bone bare, and cleaning the part with sponge; but they are occasionally so small, that some art is necessary to discover them. If a black liquor, made of burnt bone or cork, mixed with water, is rubbed on the bare skull, it will sink into the crack, and discover, when washed off, its situation; or, if the head be clean shaved, and the patient bled freely, an oedematous puffiness will appear, in a day or two, over the part affected.

Fissures are often productive of worse consequences than fractures; for there is often, at the same time, a concussion of the brain; and it is consequently necessary to ascertain this circumstance. Instances of the ill effects of fissures have happened many months after the accident. The fissure alone is not dangerous, but the violence which occasioned it, and the consequent rupture of numerous vessels, whose extravasated contents injure the bone. When this happens, an unexpected death is often the consequence.

Trepanning seems to be the properest method of relief; though the plan recommended by Mr. Bromfield, in concussions of the brain, has alone effected a cure.

Flssura Cerebri Magna Sylvii. The Sulcus which divides the anterior and middle lobes of the cerebrum on each side: it ascends obliquely backwards from the temporal ala of the os sphenoides to near the middle of the os parietale.