Before Going to Lab 1, Label the patellar reflex area and reciprocal innervation in Figure 19.2. Although the grading is subjective, grade the extension of the leg.
LAB ACTIVITY
+1 = little response hypo-reflexive
0 = no response hypo-reflexive
+2 = normal response
+3 = above normal response
+4 = exaggerated reflex hyper-reflexive
Testing the Patellar Reflex:
Test the patellar reflex. Have the subject sit on the edge of a table or a tall lab chair with their knee off the table or chair and the leg dangling and relaxed. Now ask the subject to clasp both hands in front of their chest and isometrically pull in opposite directions. This action leads to an enhancement of the chest and reinforces the patellar reflex. Palpate the patella and the tibial tuberosity, also palpate the patellar ligament located between these two structures. While the subject is pulling, strike the patellar tendon with the tapered end of a reflex hammer, causing a reinforced patellar reflex. Observe the distance of leg movement this time.
Answer the Discussion Questions with your lab group.
Complete Biopac Laboratory Guide Experiment: Effect of Physical and Mental Distraction on Patellar Reflex Knee Jerk Response.
Effector for patellar reflex arc: effector for reciprocal innervation.
Integrating center for patellar reflex arc: integrating center for reciprocal innervation.
Motor neuron for patellar reflex arc: motor neuron for reciprocal innervation.
Receptor: sensory neuron.
Figure 19.2: Patellar reflex arc.
