Touch and Temperature

Mechanoreceptors Vary In
1. Encapsulation
2. Rate of adaptation
3. Receptive field size
Receptors in Skin
1. Free nerve endings
  1. Pain, temp.
2. Merkel's disc (touch)
  1. Not encapsulated, slow-adapting, small receptive size, upper level
3. Meissner's corpuscle (touch)
  1. Encapsulated, fast-adapting, small receptive size, upper level
4. Pacinian corpuscle (vibration)
  1. Encapsulated, fast-adapting, large receptive field, lower level
5. Ruffini's ending (stretch)
  1. Not encapsulated, large receptive field, lower level, slow-adapting
Afferent fibers
1. Aa (alpha-alpha)
  1. Large, muscle fiber feedback
2. Ab (alpha-beta)
  1. Of mechanoreceptors (pacinian, ruffini, meissner, merkel)
3. Alpha-delta
  1. Pain, temp, free nerve ending
4. C-fibers
  1. Smallest. Pain, temp, skin itch receptors, free nerve ending
Dermatomes
1. skin surface areas enervated by the dorsal roots of one spinal segment.
2. Shingles
Somatosensory pathways
1. Unipolar neurons
2. Cranial nerves (facial)
  1. Carry touch & pain info from face, mouth, tongue & dura mater to cranial nerve nuclei in brainstem, then to thalamus
3. Area 1 (texture, light, touch)
4. Area 2 (size, shape, movement)
5. Area 3A (join movement)
6. Area 3B (light touch, size, shape, texture)

Zusammenfassung der Ressource

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