Cutaneous Receptors
Cutaneous receptors are sensory receptors located in the dermis, which is a layer of the skin. These receptors are responsible for sensations of touch, pressure, heat, cold, and pain. They are classified asmechanoreceptors which are associated with pressure, thermoreceptors which are associated with temperature, and nociceptors which are associated with pain (Brodal).
Functional Anatomy
There are five mechanoreceptors, free nerve endings, Meissner's corpuscles, Pacinian Corpuscles, Merkel's disks, and Ruffini's corpuscles. Table 1 shows where each receptor is located, what their function is in detecting a stimulus, and lastly what their rate of adaptation is. The strength of the stimulus is determined by the rate of action potential discharge triggered by the receptor potential. This is where the rate of adaptation comes into play for these receptors. Rapidly adapting receptors fire when a stimulus is first presented but then stop if the stimulation continues. Whereas, slowly adapting receptors will sustain discharge if the stimulation continues. The size of the receptive field of a cutaneous receptor is also important in order to discriminate between tactile stimuli. If the receptor has a large receptive field the receptor would not be able to discriminate between two stimuli placed on the same area. Also the more receptors located in one area of skin allow that area to be more sensitive to stimuli (Brodal, Purves).
Table 1
Receptor Type
Location
Function
Rate of Adaptation
Free Nerve Endings
All skin
Temperature, Pain,
Crude Touch
Slow
Meissner's Corpuscles
Glaborous skin
Touch, Pressure (dynamic)
Rapid
Pacinian Corpuscles
Subcutaneous tissue,
Interosseous membranes,
Viscera
Deep pressure,
Vibration (static)
Rapid
Merkel's Disks
All skin, Hair Follicles
Touch, Pressure (static)
Slow
Ruffini's Corpuscles
All skin
Stretching of skin
Slow
Cutaneous receptors
Modality
Type
Fiber type
Touch
Rapidly
Functional Anatomy
There are five mechanoreceptors, free nerve endings, Meissner's corpuscles, Pacinian Corpuscles, Merkel's disks, and Ruffini's corpuscles. Table 1 shows where each receptor is located, what their function is in detecting a stimulus, and lastly what their rate of adaptation is. The strength of the stimulus is determined by the rate of action potential discharge triggered by the receptor potential. This is where the rate of adaptation comes into play for these receptors. Rapidly adapting receptors fire when a stimulus is first presented but then stop if the stimulation continues. Whereas, slowly adapting receptors will sustain discharge if the stimulation continues. The size of the receptive field of a cutaneous receptor is also important in order to discriminate between tactile stimuli. If the receptor has a large receptive field the receptor would not be able to discriminate between two stimuli placed on the same area. Also the more receptors located in one area of skin allow that area to be more sensitive to stimuli (Brodal, Purves).
Table 1
Receptor Type
Location
Function
Rate of Adaptation
Free Nerve Endings
All skin
Temperature, Pain,
Crude Touch
Slow
Meissner's Corpuscles
Glaborous skin
Touch, Pressure (dynamic)
Rapid
Pacinian Corpuscles
Subcutaneous tissue,
Interosseous membranes,
Viscera
Deep pressure,
Vibration (static)
Rapid
Merkel's Disks
All skin, Hair Follicles
Touch, Pressure (static)
Slow
Ruffini's Corpuscles
All skin
Stretching of skin
Slow
Cutaneous receptors
Modality
Type
Fiber type
Touch
Rapidly