The knee-jerk reflex, also known as the patellar reflex, is
a simple reflex
that causes the contraction of the quadriceps muscle when the patellar tendon is stretched.
Is knee-jerk an innate reflex?
Pulling your hand away from a hot object, blinking because it’s very bright or kicking when someone taps the tendon below your kneecap – these are all innate reflex actions. … The knee-jerk reflex involves
a sudden kicking movement of your lower leg after the tendon just below your kneecap has been tapped
.
What kind of reflex is knee-jerk?
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
.
Is the knee-jerk reflex somatic or autonomic?
Autonomic Reflexes
Activity 1- Patellar reflex The patellar tendon reflex or knee-jerk reflex is a monosynaptic stretch reflex that assesses the nervous tissue between (and including) the L2 and L4 segments. It can be done by tapping the patellar ligament (just below the knee) with a reflex hammer.
Is the knee-jerk reflex a flexion or extension?
Knee reflex: (L2-L4) Slightly lift up the leg under the knee, and tap the patellar tendon with a reflex hammer. There should be a reflex contraction of the quadriceps muscle (
knee extension
).
What does the knee reflex test for?
The patellar reflex test is performed
to determine the integrity of the neurological function
, which is accomplished by hitting the patellar tendon below the knee cap with a test hammer [2].
What happens during knee jerk reflex?
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
.
Why is knee jerk reflex important?
This is a reflex of proprioception which
helps maintain posture and balance
, allowing to keep one’s balance with little effort or conscious thought. The patellar reflex is a clinical and classic example of the monosynaptic reflex arc.
What nerve causes knee jerk?
Although the knee jerk reflex is mediated by the
L3 and L4 nerve roots
, evidence exists that altered knee jerk expression may occur with exclusively L5 radiculopathy.
What is the doctor testing when he hits your knee?
The knee jerk reflex
is one that you may have had tested at a check up at the doctor’s office. In this test, the doctor hits your knee at a spot just below your knee cap and your leg kicks out. Try it! Have a partner sit with his or her legs crossed so that his leg can swing freely.
What are the 4 types of reflexes?
In our discussion we will examine four major reflexes that are integrated within the spinal cord:
the stretch reflex, the Golgi tendon reflex, the withdrawal reflex and the crossed extensor reflex
.
What are the three types of reflexes?
- Categories of Reflexes. Reflexes can either be visceral or somatic. …
- Stretch Reflex. One of the simplest reflexes is a stretch reflex. …
- Flexor (Withdrawal) Reflex. Recall from the beginning of this unit that when you touch a hot stove, you reflexively pull your hand away. …
- Crossed-Extensor Reflex.
What is not required for a reflex arc?
A
reflex does not require any thought input
. The path taken by the nerve impulses in a reflex is called a reflex arc. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord.
Is it bad if you have no reflex in your knee?
Pathological Reflexes. Many reflexes are normal. For example, the knee jerk is a normal reflex and
the absence of this reflex would be considered abnormal
. Many reflexes are normal in a newborn or young child but would be abnormal if found in an adult.
What is a normal knee 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.
