Monday, August 10, 2009

Tendon Reflex

Tendon reflex, like the patella reflex so often checked by doctors, tapping with the little rubber hammer, is an involuntary response to stimulus that prompts automatic reaction of a limb or body part. Some reflex actions like the patellar reflex operate in a closed neural circuit, called a "reflex arc", that saves time and thought, bypassing the conscious and immediately eliciting a quick response.

The relative health status of some individuals is also reflected in involuntary responses. When the doctor checks my patellar reflexes, watch out!, because some of them are hyperactive. Especially the right leg, which exhibits what is called "tonic" reflex, or just "tone" for short. Too much "tone" means that flexors and extensors are opposing each other too much to allow freedom of voluntary movement. When the doctor taps lightly on the ligament below the patella, my leg responds in a fairly dramatic way.


B. Perky said...

Then together we would respond just right because I respond not at all most of the time and the rest of the time, after several "hits," just a little.

Jim Cobabe said...

Yeah, this trick never worked much with me before. It depends on muscle tone. I had to have a stroke first to get it to work. Don't try this at home, it isn't worth the trouble.

Jim Cobabe said...

Of interest to me was the fact that reflex action depends on some specialize nerve arrangments, far different than the normal wiring we expect. I was surprised to learn about reflex arcs and how they function.