Knee jerk is a deep tendon reflex of lowerlimb .
It is increased tendon reflex activity suggests increased
excitability of the anterior horn cells in the spinal segment of the stretched
muscle due to loss of descending inhibition with a UMN or corticospinal tract
lesion.
Brisk reflexes alone, are not necessarily pathological and
it may result from anxiety
Brisk reflex is physiologically seen in anxiety
Pathologically brisk reflex is seen in pyramidal tract
lesion