Lenticular.
Greek, φακωτός.
The lenticular of the ancients was a vertical chisel cutting on one edge and struck on the other by a hammer, while the end carried a rounded button, which being smooth did not injure the brain ([Pl. XL, fig. 4]). It takes its name from the lentil-like (φακωτός) shape of the button. Galen had a high appreciation of it, and gives a full description of its principle (x. 445), which is transcribed by Paul (VI. xc):
‘The method of operating with a sort of incisor called lenticular is greatly praised by Galen, being performed without drilling after the part has been grooved all round with gouges.’
Wherefore he says:
‘If you have once exposed the place, then applying the chisel, which has at its point a blunt (rounded), smooth, lentil-shaped knob, but which longitudinally is sharp, when you apply the flat part of the lenticular to the meninges divide the cranium by striking with the small hammer. For we have all that we require in such an operation, for the membrane, even if the operator were half asleep, could not be wounded, being in contact only with the flat part of the lenticular, and if it be adherent anywhere to the calvarium the flat part of the lenticular removes its adhesion without trouble. And behind it follows the incisor or lenticular itself, dividing the skull, so that it is impossible to discover another method of operating more free from danger or more expeditious.’
The earliest illustration of the lenticular I have been able to obtain is that given by Vidus Vidius ([Pl. XL, fig. 2]). It evidently is the same instrument as that described by Galen.
Hammer.
Greek, σφῦρα; Latin, malleolus.
I have already quoted passages where the hammer is referred to as being used in cranial surgery. Paul says: ‘When you apply the flat part of the lenticular to the meninges divide the skull by striking with a small hammer,’ and again in using gouges, ‘strike gently with hammer (σφῦρα) to avoid concussion of the head’ (VII. xc).