Cutaneous.html.zip

15Mar 2022 byCutaneous.htmlCutaneousCutaneous sensation is part of the somatosensory system. Cutaneous receptors have a variety of nerve-fiber endings designed to respond to different types of energy produced in the environment. When these nerve endings are activated, you are able to feel changes in temperature, irritants, or mechanical stimuli that press, touch, or cause pain (also known as nociception). The different types of receptors are distributed throughout the skin; the distribution is not even and results in some areas having greater sensitivity to particular stimuli.After the cutaneous receptors transduce the stimuli, the sensory information is sent up to the brain via the spinal cord. The nerve fibers, which are called peripheral nerves, travel along two major pathways. One of the pathways, the medial lemniscus pathway, consists of large fibers that carry proprioceptive and touch information. The other pathway, the spinothalamic pathway, consists of smaller fibers that carry temperature and pain information. Both pathways travel up the spinal cord to the brainstem, synapse in the ventrolateral nucleus of the thalamus, and travel to the somatosensory cortex in the parietal lobe of the brain. Note that “soma” means “body”—thus, “somatosensory” means “body sensation.”Once the signals reach the somatosensory cortex in the brain, they synapse in the primary somatosensory-receiving area (S1) and are then sent to the smaller secondary receiving area (S2). You may recall that this is similar to what happens to sensory information in both the visual and auditory systems. The information goes to a primary processing area, and then it projects to a secondary area. As with the other senses we have discussed, there is a topographical organization to the brain’s receiving areas. However, the somatosensory receptive areas are not organized exactly the way our body is organized.