Flashcards in Exam #1: Sensory II Deck (35):
What is the Anterolateral System?
This is the ascending sensory tract that relays:
*Note a little light/crude touch
What is the definition of nociception?
Physiologyical reception of noxious sensory information elicited by tissue injury
*This can be MEASURED
What is pain? How does pain differ from
This is the subjective perception of discomfort in response to stimulation of sensory nerve endings
*This cannot be measured
Where is the anterolateral system anatomically?
What are the two major white matter tracts that are part of the Anterolateral System? Where are these two tracts?
- Anterior Spinothalamic Tract= in the anterior faniculus
- Lateral Spinothalamic Tract= in the anterolateral tract/ ventrolateral tract
Aside from the Anterior Spinothalamic Tract & Lateral Spinothalamic Tract, what other tracts are part of the ALS?
How are the tracts of the ALS classified phylogeneticaly?
What is the neosplinothalamic system?
- Developed later in evolution i.e. newer
- Direct pathway= information ascends directly from the spine to VLP to somatosensory
- 15 % nociceptive
What is the Paleospinothalamic system?
- Indirect pathway= info goes to the reticular formation-->thalamus
- 85% nociceptive fibers
****Most of the information carried by this pathway is NOT entered into consciousness
What is a dermatome?
Band of skin that is innervated by a pair (right & left) of spinal nerves
What are the three neurons of the Neospinothalamic Pathway?
2) Dorsal horn
3) VPL of thalamus
What type of sensation is carried by the Neospinothalamic Pathway?
- Fast, sharp, & well-localized pain sensation
This information enters CONSCIOUSNESS
Where does the central process of the free nerve ending in the Neospinothalamic Pathway enter the spinal cord? What happens here?
Dorsolateral Tract of Lissauer (White Matter)
- Bifurcates into short ascending & descending branches
- Synapse with the Substantis Gelatinosa in the dorsal horn of the gray matter
What is the function of the Substantia Gelatinosa?
Modulation of nociception
****Thus, b/c of the SG, some nociception is attenuated
After sensory information passes through the SG, where does it go?
- Anterior white commisure
- Axons of the nucleus proprious
- Ascends ventrolateral funiculus
Outline the spinothalamic tract.
1) DRG pseudounipolar
4) Axon from NP
5) Ascend spinal cord--axons to Reticular formation in caudal medulla
8) VPL Thalamus
9) Primary somatosensory cortex
Where does the decussation of the spinothalamic tract occur?
Spinal cord level
What type of fibers convey the nociception from the receptor to the DRG?
A-delta i.e. lightly myelinated
What is radicular pain?
Pain resulting from irritation of a dorsal root of a spinal nerve
If there is a lesion in the right ascending spinothalamic tract?
Loss of pain & temperature sensation from contralateral side of the body 2+ segments below the lesion b/c of bifurcation of the dorsolateral tract of Lissauer
IF the lesion in the neospinothalamic system is in the ascending tract, where are the symptoms?
Opposite or contralateral side
Patient has L1 distribution of pain in the left leg. Where could tractotomy be preformed?
T9 on the right
Outline the mechanism of referred pain.
- Sensory fibers bringing sensory information from the two involved structures synapses on the SAME second order neuron
- Neospinothalamic tract
What is syringomyelia?
This is a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in pain, paralysis, weakness, and stiffness in the back, shoulders, and extremities.
What fibers are effected by the enlargement of the central canal of the cord?
Anterior white commissure; carries sensory signals from second order neurons that are crossing over
How will occlusion of the Anterior Cerebral Artery effect the ALS?
Sensory deficits in the contralateral leg & foot
How will occlusion of the MCA effect the ALS?
Sensory deficits in the contralateral upper limb & foot
What are the lenticulostriate arteries?
Branches of the MCA that supply the Thalamus
What will occlusion of the lenticulstriate arteries cause in regards to the ALS pathway?
Sesory deficits on the contralateral side
****Note that this is similar to what happens with the DC-ML
What does the PCA supply?
Occidental lobe & the inferior temporal lobe, including the spinothalamic tract
What does occlusion of the PCA result in, in regards to the ALS?
Sensory deficit on the contralateral side
What does the basilar artery supply?
Caudal pons--spinothalamic tract
What does occlusion of the basilar artery supply result in, in regards to the ALS?
What do the vertebral arteries supply?