In the knee-jerk reflex circuit, the dorsal horn of the spinal cord contains the
A) interneurons that connect sensory input to extensor muscle motor neurons.
B) stretch receptors.
C) cell bodies of motor neurons.
D) axons of sensory neurons.
E) white matter of the spinal cord.

Question

Quizplus · Accepted Answer

The knee-jerk reflex circuit involves sensory input from stretch receptors in the quadriceps muscle, which is transmitted via sensory neurons (whose axons are located in the dorsal root ganglia) to the dorsal horn of the spinal cord. Here, the sensory neurons synapse with interneurons, which in turn synapse with motor neurons in the ventral horn of the spinal cord that activate the quadriceps muscle. Therefore, the dorsal horn of the spinal cord contains the axons of sensory neurons that transmit the initial sensory input in the knee-jerk reflex circuit.

In the Knee-Jerk Reflex Circuit, the Dorsal Horn of the Spinal