Two-Point Threshold

1. Two-Point Threshold Receptors and Somatic Senses

2. Meissner’s Corpuscles • Meissner's Corpuscles are encapsulated dendritic endings • surrounded by CT wrapping • mechanoreceptors • detect light touch • abundant in the hairless portions of skin (i.e. lips, fingertips, palms, soles, nipples, external genitalia)

3. Pacinian Corpuscles • Pacinian Corpuscles are also encapsulated dendritic endings: • surrounded by CT wrapping • mechanoreceptors • detect heavy pressure • abundant in deep subcutaneous tissues of hands, feet, penis, clitoris, urethra, breasts

4. This exercise tests your partner’s ability to detect the difference between two points on the skin simultaneously on different areas of the body. Tells you the area innervated by a single receptor (neuron) 1. Hold the two points closely together. (could be tips of forceps, pens, calipers, etc...) Push down GENTLY! 2. Ask the subject to report whether they feel one or two points. Record the results. 3. Move the points 1mm across (remove them from the subjects arm and use a ruler to measure). 4. Reapply the points to your partner’s skin. 5. Ask the subject to report whether they feel one or two points. Record the results. 6. Repeat steps 4-6 until the subject can feel the difference between the two points. This is the Two-Point Threshold. (This means two receptors are being stimulated instead of one.) Two-Point Threshold