Which of the following normally occurs when a doctor's reflex hammer taps a patient's patellar tendon?
A)Alpha motor neurons stimulate contraction of intrafusal fibers in extensor muscles.
B)Alpha motor neurons stimulate contraction of extrafusal fibers in extensor muscles.
C)Alpha motor neurons that innervate ipsilateral flexor muscles are stimulated.
D)Inhibitory interneurons reduce action potential firing in alpha motor neurons to extrafusal fibers of extensor muscles.
E)Golgi tendon organs in the patellar tendon stimulate the contraction of extrafusal fibers of extensor muscles.

Question

Which of the following normally occurs when a doctor's reflex hammer taps a patient's patellar tendon?
A)Alpha motor neurons stimulate contraction of intrafusal fibers in extensor muscles.
B)Alpha motor neurons stimulate contraction of extrafusal fibers in extensor muscles.
C)Alpha motor neurons that innervate ipsilateral flexor muscles are stimulated.
D)Inhibitory interneurons reduce action potential firing in alpha motor neurons to extrafusal fibers of extensor muscles.
E)Golgi tendon organs in the patellar tendon stimulate the contraction of extrafusal fibers of extensor muscles.

Quizplus · Accepted Answer

When a doctor's reflex hammer taps a patient's patellar tendon, it causes the muscle spindle in the quadriceps muscle to stretch. This stretch activates sensory neurons, which synapse on alpha motor neurons in the spinal cord. The alpha motor neurons then stimulate the contraction of extrafusal fibers in the same quadriceps muscle to cause the knee jerk reflex.

Which of the Following Normally Occurs When a Doctor's Reflex