Term
|
Definition
-receptors: skin (a-beta fibers)
-cell bodies: dorsal root ganglion
-primary afferent axons (skin) to spinal nerves to spinal cord
-primary afferent axons ascend the spinal cord via ipsilateral dorsal columns (white matter) |
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Term
| pacinian corpuscle (largest) |
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Definition
-10-15% of hand mechanoreceptors
-sensitive to high frequency vibration
-low spatial acuit (10+mm)
-"onion-like" |
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Term
| ruffini's endings (second largest) |
|
Definition
-20% of hand mechanoreceptors
-sensitive to skin stretch
-low spatial acuity (7mm) |
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Term
| Meissner's corpuscle (1/10th of pacinian) |
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Definition
-40% of hand mechanoreceptors
-sensitive to low frequency vibration
-intermediate spatial acuity (3mm) |
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Term
|
Definition
-25% of hand mechanoreceptors, especially fingertips
-sensitive to edges, points, curvature
-high spatial acuity (0.5mm) |
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|
Term
Structure of specialized endings
contribute to receptor function (e.g. pacinian corpuscle) |
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Definition
| onion-like capsule confers sensitivity to high frequency vibrating stimuli but not steady pressure |
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Term
|
Definition
-skin innervated by right and left dorsal roots for a single spinal segment
-numbered by spinal seg providing innervation
-overlap (cutting one doesn't lead to loss of all sensation) |
|
|
Term
| topographic organization of dorsal columns |
|
Definition
lower body axons in gracile tract (medial)
upper body axons in cuneate tract (lateral) |
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