knee jerk reflex I all 4 grades with demo on patients I brisk tendon reflex |rootvalue I neurology

The Knee Jerk /Patellar Reflex : Grading of Reflexes , learn with demonstration on the patients (#MadeEasy)
Can’t remember grading of reflexes ?
Learn grading with examples.
#coticospinaltractdisorders

how to perform knee jerk reflex on a patient?
muscles involved in this knee reflex?

It is a deep tendon reflex.

The patellar reflex is contraction of the quadriceps femoris muscle, with resulting extension of the knee, in response to percussion of the patellar tendon.


A firm tap on the tendon draws the patella down, stretching the quadriceps an provoking reflex contraction.


There is a latency of around 18ms between stretch on the patellar tendon and the beginning of contraction of the quadriceps femoris muscle.


Root Value of the knee reflex :
Femoral nerve (L2-L4)

The #quadriceps muscle is composed of four muscles :

I.Rectus femoris
II.Vastus lateralis
III.Vastus medialis
IV.Vastus intermedius

Grading:
0 = Absent
1+ = Present but diminished
2+ = Normal
3+ = Increased but not necessarily pathological
4+ = Markedly hyperactive/ pathological/sometimes accompanied by sustained clonus

Significance:

Hyperactive reflexes is seen in UMN lesions i.e corticospinal tract disorders.

Hypoactive reflex is seen in LMN lesions i.e in neuropathy, spinal cord disorders.