(From claudo, to shut). A nail or button. An instrument in surgery mentioned by Amatus Lusitanus, to be introduced into the ulcerated palate, for the better articulation of the voice. Sometimes this word signifies indurated tubercles of the womb, and are distinguished by a similar appellation.

Clavus, a corn, called also spina pedum, colli, eon-dylomata, and tyllomata. Dr. Cullen defines a corn to be a lamellated hard thickening of the cuticle. He ranks it as a genus of disease in the class locales, and order tumores.

Corns are a sort of horny excresence growing on the feet and toes, sometimes on the hands of labouring people. These callosities resemble an inverted wart, and are seated in the cutis and cuticle, arising chiefly from pressure and irritation, and are excessively painful when rooted near a nerve. The easiest and best method of cure, is to take off all uneasy pressure, and apply a piece of plaster, spread with soap, or plaster of litharge, with some opium, little more than the size of the corn, which may be closed on the part for four or five days together, to render its surface soft. That part which appears sodden must be pared away, but by no means so low as to touch the cutis vera; after which the plaster is to be renewed, and the whole process may be repeated in five or six days, till the corn appears likely to separate with its root, or waste away. Soaking the part in bran and warm water is very useful previous to each cutting. Hog's gall dried in the bladder, spread thin upon a rag and applied to the corn only, has often proved efficacious: it is apt to inflame the part a little, but the corn generally withers after a few applications of this kind, and is wholly separated. See White's Surgery; also Bell's Surgery, vol. v. p. 539. See Spinae pedum.

Clavus hystericus, (so called from clavus, a nail; as the sensation resembles the driving a nail into the head). A symptom attending some cases of hysteria, which is thus described by Sydenham: "Hysterics sometimes attack the external parts of the head, between the cranium and the pericranium, occasioning violent pain, which continues fixed in one place, not exceeding the breadth of one's thumb; and it is also accompanied with enormous vomitings." (See Cephalalgia.) Such again attend a venereal caries, or an exostosis of some bone of the cranium.

Clavus oculorum. See Staphyloma.