What reflex is a doctor invoking when tapping the knee with a rubber hammer?

Answer 1

knee-jerk reflex,also called patellar reflex is a

sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, which lies just below the kneecap. One of the several positions that a subject may take for the test is to sit with knees bent and with one leg crossed over the other so that the upper foot hangs clear of the floor. The sharp tap on the tendon slightly stretches the quadriceps, the complex of muscles at the front of the upper leg. In reaction these muscles contract, and the contraction tends to straighten the leg in a kicking motion. Exaggeration or absence of the reaction suggests that there may be damage to the central nervous system. The knee jerk can also be helpful in recognizing thyroid disease.

So, basically, it's a nerve reflex, you can't control it, it's just like when you put your hand on a hot kettle it pulls away, you can't help it.

Answer 2

When a doctor taps the knee with a small hammer he or she is testing a person's reflexes (sensory receptors, sensory neurons, spinal chord, interneurons, motor neurons, brain). If a person's leg instantly jerks upwards his/her reflexes are fine. His/her sensory receptors are affected by the stimulus (tap on the knee), which causes an action potential that travels along the sensory neurons and reaches the interneurons in the spinal chord, where it splits to either brain or motor neurons, and finally travels through motor neurons causing the muscle to flex (upward jerk).

Answer 3

A doctor taps the patellar ligament with a rubber reflex hammer. This is invoking the patellar, or knee jerk, reflex.

Answer 4

To see if your nerve cells are working correctly.

Answer 5

Without going into detail, the reason the knee "jumps" when the doctor hits it is because of a reflex.

Answer 6

reflexes