Primary Pain Pathway Flashcards
Types of Nociception Stimuli
Mechanical - deforms skin and has potential to cause cell disruption
Extremes of temp
Chemical (inflammation)
How pain pathways travel together?
In adjacent tracts of the A-L system of the spinal cord and spinal lemniscus of the brainstem but terminate in different regions of the CNS to provide different aspects of the pain experience.
What do pain pathways do?
- Provide meaning and saliency of the stimulus.
- Provide autonomic and behavioral responses to the stimulus
- Produce memory of the stimulus and its context
- Create attention to and arousal from the stimulus
- Activate descending inhibitory and/or faciliatory pathways
Spinothalamic Pathway
Primary pain pathway
- Pathway for the body (not face)
- Awareness and localization of noxious stimuli
Spinothalamic pathway receptor is?
Nociceptor
Spinothalmaic pathway afferent axon are?
Delta
C
-Both pseudounipolar
What tract does the spinothalamic pathway use?
The spinothalamic tract in the spinal cord and brainstem
Begins in the spinal cord and terminates in the ventral posterolateral nucleus of the thalamus
Where is the spinothalamic tract?
located in the anterolateral aspect of the spinal cord
located in the lateral aspect of the brainstem
What does the spinothalamic pathway contain?
Primary somatosensory cortex on the postcentral gyrus laterally or on the posterior paracentral gryus medially. These gyri are located within the parietal lobe.
What is the primary somatosensory cortex?
Sensory homunculus (little man) with somatotopic organization.
What is the primary somatosensory cortex?
More sensitive areas have larger areas of representation in the cortex
-Hand, face, lips and foot have large areas of representation.
What is the primary somatosensory cortex innervate?
- trunk, upper extremity, hand and face represented superiorly and laterally on the postcentral gyrus.
- Lower extremity represented medially on the posterior paracentral gryus.
What happens when a nociceptor is stimulated?
An AP is generated and propagates along a Delta or C first-order afferent neuron (whose soma is in a DRG).
The central axon terminates in the dorsal horn of the entering spinal cord segment.
What does the first-order afferent neuron synapse with?
A second-order neuron in the dorsal horn. Second-order neuron crosses the spinal cord to the contralateral STT and travels up the STT to the VPL nucleus of the thalamus.
When the second-order neuron synapses with what?
A third-order neuron in the VPL nucleus of the thalamus. The third-order neuron goes to the primary somatosensory cortex in the parietal lobe to conscious nociception perception and localization of the noxious stimulus.
