Question

After the primary sensory afferent synapses on the second order neuron, the second order neuron _________

a. synapses in the thalamus
b. crosses midline
c. travels down to the lower extremities
and travels to the _____________where it synapses on a 3rd order neuron.
a. brainstem
b. thalamus
c. spinal cord

Answer 1

The correct answer is option

1. crosses midline.

2. thalamus.

Step-by-step explanation:

The somatosensory system divides the afferent neurons in the pathway into three types: primary, secondary and tertiary.

Primary afferent neurons transmit the impulse from the organ to the synapse at the secondary afferent neurons in the dorsal root ganglion.

The secondary neurons carry the impulse from primary neurons to tertiary neurons which decussate at the medulla through medial lemniscus. After these neurons enter and synapse to the third-order neurons in the thalamus region of the brain from which the impulses travel to the parietal lobe.

Thus, crosses midline and thalamus are the correct options.