TREPHINE

n. Treaf-in'. Gr., rpviraioj. rpvwavov (from rpviraK, to bore). Lat., trepanum, trypan on. Fr., trephine, trepan. Ger., Schadelbohrer, Drillbohrer, Drehbohrer, Trephina, Trepan. An instrument for cutting or sawing a circular opening, generally for sawing such an opening in the skull; consisting of a crown (a steel tube with saw-teeth at its free end\ a shaft, and a handle. [E.] Brace t. A t. fitted into an ordinary carpenter's brace. [E.] Conical t. A t. the crown of which has the shape of a truncated cone, and is provided with oblique ridges on its outer surface, so that its progre ceases as soon as the bone has been cut through, [a, 34.] Corneal t. Of Bowman, a small cutting drill or t. designed to excise a defined circular portion of the apex of a conical cornea. The instrument Is rotated by the finger and thumb. De Wecker's A, ape; Aa. at; AS, ah; A*, all; Ch, chin; Cha, loch (Scottish); [s. 642]