I love old medical photos like these. This is a picture demonstrating Jendrassik Maneuver
The Jendrassik maneuver is a medical maneuver wherein the patient flexes both sets of fingers into a hook-like form and interlocks those sets of fingers together. The tendon below the patient’s knee is then hit with areflex hammer to elicit the patellar reflex. The elicited response is compared with the reflex result of the same action when the maneuver is not in use. Often a larger reflex response will be observed when the patient is occupied with the maneuver, as the maneuver may prevent the patient from consciously inhibiting or influencing his or her response to the hammer. This effect was first observed in the late 19th century by Hungarian physician Erno Jendrassik, whom it was named after.