knee jerk

[blueyedevil]

what is the hammer called that is used for the knee jerk test

[jonn4y]

Apparently they are called:
"Percussor or Patella Hammer"

[Peter Pedant]

reflex hammer

[brachiopod]

4lb lump hammer

[brachiopod]

OK, my doctor must have been a sadist then.....

[Golem]

Like many things associated with medicine this device is named after the doctor who created it, in this case John Madison Taylor, 1855-1931. He practiced pediatrics, neurology, and physical medicine in Philadelphia, and so we have Taylor's Hammer, one of the most common designs still in use. This is a description from the meeting of the Philadelphia Neurological Society on Feb 27, 1888 when Taylor first presented it,

"... devised to serve as nearly as possible all ends for which a hammer is likely to be called into use by clinicians...In shape it is a cone flattened on the opposite side, with apex and base carefully beveled or rounded, of about the thickness throughout of the human index finger. The material is moderately soft rubber. It is held by an encircling band of metal midway between the apex and base transversely, and from it, on the edge, depends the straight handle. The handle is rigid though light, it being Dr. Taylor's opinion that this had better be under the full control of the wilder. If elastic as recommended by some, an element of uncertainty enters in the degree of force used in the blow. The special feature of this hammer is that the shape of the striking surface is like the outer surface of the extended hand, palm downward, which is most often used in obtaining tendon jerk. The rounded apex is adopted to reach the biceps tendon at the bend of the arm .... This little tool will also well serve to elicit chest sounds, to percuss the abdomen, and in fact, is useful whenever an elastic hammer is needed. The material being of soft rubber, the blow does not hurt the intercepting fingers as does the hammer usually employed to strike the tendons and muscles."

Other doctors have produced variations on a theme and there are Troemner, Dejerine and Babinski Hammers each designed with a speciality in mind.