- Function
- Mechanical, thermal, chemical, polymodal pain
- Quantity
- Millions of free endings (Aδ + C)
- Density
- High throughout skin; also muscle, joint, viscera
- Distribution
- Skin, deep somatic tissues, most viscera
Fast Aδ “first pain” and slow C “second pain.” Spatial acuity is coarser than touch but still follows a similar body gradient (finest on fingertips and face).