Mod5-Obj4: Somatosensory pathways

Question 1

Somatosensory pathways

Answer 1

Convey general (somatosensory) sensory information from receptors (skin, musculature, joints) to the brain

Question 2

Somatosensory pathways involve threes successive neurons

Answer 2

1. ) First-order neuron
2. ) Second-oder neuron
3. ) Third-order neuron

Question 3

Sensory pathways

Answer 3

Relay sensory input from the receptor to the brain

• Are multi-neuron pathways and usually involve:
  1. ) A sensory neuron of the PNS
  2. ) Two interneurons in the CNS

Question 4

Example of a sensory pathway

Answer 4

Pain receptor, sensory neuron, spinal cord interneuron, brain interneuron, cerebral cortex

Question 5

First-order neurons (Sensory neurons)

Answer 5

Conduct sensory input from receptors to the spinal cord

• Unipolar neurons
• The cell body resides in a dorsal root ganglion
• The axon enters the posterior fray horn via a dorsal root and synapses with a second-order neuron within a nucleus

Question 6

Second-order neurons (Spinal cord interneurons)

Answer 6

Conduct sensory input to the thalamus (or cerebellum)

• Multipolar interneurons
• The cell body resides in a sensory nucleus of the posterior gray horn
• The axon travels in a specific spinal cord tract in a particular white column

Question 7

Third-order neurons (brain interneurons)

Answer 7

Conduct sensory input from thalamus to a specific region of the primary somatosensory cortex

• Multipolar interneurons
• The cell body resides in the thalamus
• The axon travels in a specific projection tract to a specific region of the primary somatosensory cortex