A site for medical students - Practical,Theory,Osce Notes

Basic facts about the Knee Jerk

Methods of eliciting the  Knee Jerk
The knee jerk can be elicited with both knees flexed and resting on the forearm of the examiner.
In the silling position this can be done with the knee hanging down.
It can also be done with sitting position with legs crossed.

Innervation of knee jerk is
L3, L4

What is Pendular Knee Jerk
By definition pendular knee jerk has more than 3 oscillations that is equidistant from the neutral position.
This is seen in cerebellar lesion.
Hung up Knee jerk is seen in the following conditions.
Chorea - Choreic movement of quadriceps is seen.
Hypothyroidism-there is prolonged relaxation.

How to elicit knee jerk in amputated leg/removed Patella
You should place a finger above the patella.
Ask the patient to keep the legs extended.
Then you strike in a peripheral direction the patella will be pulled up.