Pain Flashcards
Where is the insular cortex located?
If you retract the lateral sulcus of your brain you get to a deep structure called the insular cortex
What is the insular cortex?
a portion of the cerebral cortex folded deep within the lateral sulcus
What does the lateral sulcus separate?
the fissure separating the temporal lobe from the parietal and frontal lobes
How is the somatosensory cortex involved in pain?
tells us where the pain is and the magnitude of the sensation
What are the 3 components of the pain matrix?
- Sensory/discriminative; contributing to perception and the location of pain
- Affective; experience the negative, anxiety-provoking nature of pain
- Associative
How is the insula involved in pain?
Linked to the imagination of pain
What are the 2 major conscious ascending tracts?
- The Dorsal Column-Medial Lemniscal Pathway
- The Anterolateral System which consists of;
- Anterior spinothalamic tract
- Lateral spinothalamic trac
What is The Dorsal Column-Medial Lemniscal Pathway responsible for?
Carries ensory modalities of fine touch (tactile sensation), vibration and proprioception.
What is the lateral spinothalamic tract responsible for?
carries the sensory modalities of pain and temperature.
What is the ventral spinothalamic tract responsible for?
carries the sensory modalities of crude touch and pressure.
What is Brown-Sequard syndrome (BSS)?
Hemisection of the spinal cord resulting in paralysis and loss of proprioception on the ipsilateral side as the injury or lesion, and loss of pain and temperature sensation on the contralateral side as the lesion.
General pain pathway:
- Nociceptor
- Afferent fibre of 1st order neuron goes to dorsal horn of spinal cord where it synapses with 2nd order neuron
- 2nd order neuron transmits information up lateral spinothalamic tract and travels to thalamus.
- 3rd order neuron goes to somatosensory cortex
Which spinothalamic tract does pain information travel in?
Lateral
What is the nocebo effect?
The nocebo effect can also occur when a doctor tells you a surgery or procedure could have negative results e.g. patients frequently stop their statins as they are told it may worsen muscle aches
What are the 2 important ways in which you can become less sensitive to pain?
- Gate control theory of pain
- Descending inhibitory pain fibres
What 2 types of fibres are pain fibres?
- C fibres
- A delta fibres
Describe C fibres
C-fibers are the smallest diameter, non-myelinated, and slowest sensory and motor conductivity. These fibers mediate the sensation of heat and the primary components of hot sensation and pain. More aching dull pain.
Describe a-delta fibres
A-delta fibers are small, myelinated, and moderate sensory conductivity speed. Slightly faster than C fibres. These fibers mediate the sensation of cold and the secondary components of cold sensation and pain. More sharp, quick pain, associated with reflexes.
What do nociceptors detect?
Noxious stimulus
What do mechanoreceptors detect?
Cutaneous mechanoreceptors respond to mechanical stimuli that result from physical interaction, including pressure and vibration (i.e. touch).
Where are mechanoreceptors located?
They are located in the skin, like other cutaneous receptors.
What type of fibres are mechanoreceptors innervated by? What is the exception to this?
They are all innervated by Aβ fibers, except the mechanorecepting free nerve endings, which are innervated by Aδ fibers.
Describe a-beta fibres
A-beta fibers are intermediate size, myelinated, and fastest sensory conductivity. These fibers mediate the sensation of touch, mild pressure, vibration, and joint positioning sensations. These are measured in the sensory nerve conduction tests of standard electrodiagnostic studies (EMG/NCV).
Which spinothalamic tract does touch information (from mechanoreceptors) enter?
nter the anterior spinothalamic tract.
