N12 - Pain and nociception 2 Flashcards
Name the trigeminal nucleus’s (4) from superior to inferior.
- main sensory nucleus
- oralis
- interpolaris
- caudalis
what are the two types of 2nd order neurones in nociception?
- nociceptive specific
- wide dynamic range (nociceptive non-specific)
Describe nociceptive specific neurones.
- Inputs from nociceptors only
- Presence and location of noxious stimulus
Describe wide dynamic range (nociceptive non-specific).
- Inputs from nociceptors ,mechanoreceptors and thermoreceptors
- Respond a wide range of stimulus intensities
- Grade severity
where do 2nd order neurons go to?
Contralateral thalamus :
- via trigemino-thalamic tract
- some go via reticular formation
- ventrobasal nuclei
- posterior and medial nuclei (emotional responses and motor responses)
when does it go from the thalamus?
- Primary somatosensory cortex
- Insula
- Cingulate gyrus ‐ emotion
what can happen at the first synapse?
-Interactions between pathways :
>divergence and convergence
>hyperalgesia, radiating and referred pain
-Modulation/modification of the signal :
>gate control theory (segmental and descending controls)
>diffuse noxious inhibitory controls
what is divergence?
Final branching of primary afferent
what is convergence?
- numerous pre-synaptic axons converge in a 2nd order neurone
- allows summation
- spatial inaccuracies
what is hyperalgesia?
Increased pain from a stimulus that normally provokes pain
what is radiating pain?
pain appears to be spread beyond the area affected
what is referred pain?
Pain appears originate from an area that is different to the injured area
Describe referred pain.
-usually from a deep to superficial structure
-to a tissue that produces sensory activity
-usually segmental :
>heart to left arm
>maxillary sinus to teeth
>appendix to abdominal skin
How does gate theory work?
-Gate = inhibitory interneurons
- Interneurons activated by:
>segmental inputs
>descending controls
Name excitatory neurotransmitters.
- substance P
- CGRP
- Glutamate
