MS Hunter 251 f.43r, Full page illustration of use of surgical instruments in operation for...

Medical treatise by John of Arderne concerned with the treatment of anal fistula The instruments depicted to the left, from left to right, are: the 'sequere me' ('follow me') a flexible probe, so called because it was the guide to be followed by other instruments; a syringe; the 'Acus rostrata' or snouted needle, a grooved director along which the scalpel was passed; the 'fraenum Caesaris' or strong thread, a ligature that constricted the rectal side of the fistula; the 'tendiculum', which was used to keep the ligature taut whilst the fistula was being divided; another syringe. The 'cochlear' (or shield) is shown at the top; this was probably held by the surgeon's mate and was used to protect the rectum during the operation. At the bottom is another snouted needle accompanied by a razor like scalpel.