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Neuro 8
WVSOM -- Neuroanatomy -- Somatosensory Pathways Test 1
| Question | Answer |
|---|---|
| What are the somatosensory pathways concerned with? | conveying information regarding specific sensory modalities to the cerebral cortex for conscious perception |
| What are the 2 ascending spinal pathways? | dorsol column/medial lemniscus pathway and anterior lateral system |
| What is the dorsal colum/medial lemniscus also called? | dorsal column pathway and dorsal column system as well as DCML |
| What is the DCML involved with? | carries information concerned with fine touch, proprioception and vibration |
| What sensory receptors are involved with the DCML? | pacinian corpuscles, joint receptors, ruffini corpuscles, meissner’s corpuscles, GTO and muscle spindles |
| How do axons enter the spinal cord into the DCML pathway? | central processes of DRG enter the spinal cord in the posterior horn and enter posterior funiculus. |
| How does the pathway change depending on location of entry into the spinal cord? | axons form higher levels of the cord enter the posterior funiculus but assume a more lateral position. This works out as cervical are most lateral and sacral are most medial |
| What is the fasciculus gracilis? | present at all levels. Contains long ascending branches of fibers from sacral, lumber and lower 6 thoracic roots |
| What is the fasciculus curneatus? | appears around T7. Contains long ascending branches from the upper 6 thoracic and all cervical dorsal roots |
| Where are the 1st order neurons in the DCML pathway? | neurons in DRG which send central processes ascending in fasciculus gracilis and cuneatus |
| Describe the route in which the first order neurons of the DCML ascend in? | ascend ipsilaterally and terminate on the nuclei in the medulla. |
| What arises form the nucleus gracilis and cuneatus in the medulla? | 2nd order neurons which project ventromedially as internal arcuate fibers |
| How do internal arcuate fibers travel? | they decussate and form a compact fiber buncle on each side of the brain stem called the medial lemniscus |
| What is the medial lemniscus? | compact fiber bundle on each side of brain stem made form internal arcuate fibers |
| Describe the location of the medial lemniscus. | ascends throu the contralateral half of the brain stem and its fibers terminate in the VPL of the thalamus |
| Where are the 3rd order neurons of the DCML? | travel from VPL of thalamus to the postcenteral gyrus of cerebral cortex (somatosensory cortex) |
| Where is the somatosensory cortex? | postcentral gyrus |
| How many neurons in the Anterior Lateral system? | 3 |
| Where are first order neurons in ALS? | DRG |
| Where are second order neurons in ALS? | dorsal horn to VPL |
| Where are third order neurons in ALS? | VPL to somatosensory cortex |
| What does the ALS do? | conduct pain, temperature and crude touch info |
| Describe the role of first order neurons in ALS. | receives input from seonsory receptors and projects to the dorsal horn where the neurons split. They then travel 1 to 3 segments upa dn down the cord in the dorsolateral tract and enter the dorsal horn where they synapse |
| Describe the path of the second order neurons in the ALS pathway. | from the dorsal horn they immediately cross the cord in the ventral white commissure. They then ascend the spinal cord in the ALS and synapse in the VPL. |
| Where do 3rd order neurons travel in ALS pathway? | from the VPL to the somatosensory cortex |
Created by:
tjamrose
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