Which of the Following Occurs Last (Patellar Tendon Reflex)

Question

Which of the following occurs last (patellar tendon reflex)?
A) The effector organ contracts.
B) The action potential travels along the efferent neuron to the quadriceps femoris.
C) The action potential travels along the sensory neuron to the spinal cord.
D) The muscle receptors of the quadriceps femoris are stimulated when the patellar ligament is stretched.

Accepted Answer

The patellar tendon reflex follows the sequence: stimulation of muscle receptors in quadriceps femoris -> sensory neuron triggers action potential -> action potential travels to spinal cord -> synapse with motor neuron in spinal cord -> motor neuron sends action potential to quadriceps femoris -> contraction of quadriceps femoris. Therefore, the effector organ (quadriceps femoris) contracts last as a result of the reflex arc.