Chapter 12, Problem 6RAC

Several of the events that occur between the time a physician strikes a patient’s patellar tendon with a rubber hammer and the time the quadriceps femoris contracts (knee-jerk reflex) are listed below:

(1) increased frequency of action potentials in sensory neurons
(2) stretch of the muscle spindles
(3) increased frequency of action potentials in the alpha motor neurons
(4) stretch of the quadriceps femoris
(5) contraction of the quadriceps lemons
Which of the following most closely describes the sequence of events as they normally occur?
a. 4,12,3,5  c. 1,4,3,25   e. 4,2,3,1,5
b. 4.1,3,2,5   d. 4,2,1,3,5