How do you describe the knee-jerk reflex?
knee-jerk reflex, also called patellar reflex, sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, which lies just below the kneecap. In reaction these muscles contract, and the contraction tends to straighten the leg in a kicking motion.
What is the point of the knee-jerk reflex?
The primary purpose of the patellar reflex, which is the stretch reflex of the quadriceps femoris muscle in your anterior thigh, is to prevent the stretching of the quadriceps. The patellar reflex is illustrated in Figure 2. The patellar tendon attaches the quadriceps muscle to the tibia bone of the lower leg.
What is meant by knee jerk reaction?
The idiom “a knee jerk reaction” means that you respond to something in an equally unthinking way. This figurative meaning of knee jerk came from the physical reflex — which is called a “patellar reflex” by doctors, and which was discovered and named in the 1870’s.
What is a normal knee-jerk reflex?
The normal knee-jerk reflex involves no input to or from the brain. The normal knee-jerk or, “patellar jerk,” reflex is elicited when the knee is tapped below the knee cap (patella). Sensors that detect stretching of the tendon of this area send electrical impulses back to the spinal cord.
Why does the doctor taps your knee with a hammer?
A reflex can be decreased or absent if there is a problem with the nerve supply. To test your reflexes, your doctor will use a rubber hammer to tap firmly on the tendon. If certain reflexes are decreased or absent, it will show what nerve might be compressed. Not all nerve roots have a reflex associated with them.
Does the knee-jerk reflex involve the brain?
Doctors will test reflexes by tapping the tendon just below the knee, and this causes the leg to kick out. This knee-jerk reflex is an example of a simple monosynaptic reflex. This quick response is called a reflex, and reflexes occur without conscious thinking or planning, meaning the brain is not involved in them.
What causes knee jerks?
The normal knee-jerk or, “patellar jerk,” reflex is elicited when the knee is tapped below the knee cap (patella). Sensors that detect stretching of the tendon of this area send electrical impulses back to the spinal cord.
What is an example of a knee-jerk?
You use the phrase ‘Knee Jerk Reaction’ to indicate that you’ve made an automatic response to something. Example of use: “I hauled off and hit him when he jumped out at me. I know he was playing a trick, but it was a knee jerk reaction!”
What is the knee-jerk reflex an example of?
Doctors will test reflexes by tapping the tendon just below the knee, and this causes the leg to kick out. This knee-jerk reflex is an example of a simple monosynaptic reflex.
What happens during a knee jerk reflex?
Knee-jerk reflex, also called patellar reflex, sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, which lies just below the kneecap.
What nerves is responsible for the knee jerk reflex?
The knee jerk reflex is mediated by the L3 and L4 nerve roots, mainly L4. How does the knee jerk reflex protect the body? Reflexes protect your body from harmful things.
What is the function of the knee jerk reflex?
The patellar reflex or knee jerk is a monosynaptic reflex. Striking the patellar tendon with a tendon hammer just below the patella stretches the quadriceps tendon . This stimulates stretch sensory receptors (most importantly, muscle spindles ) that trigger an afferent impulse in a sensory nerve fiber of the femoral nerve leading to the lumbar region of the spinal cord.
What is the importance of a knee jerk reflex?
Knee-jerk reflex. 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 .