13.1: Introduction to the Somatic Senses
- Page ID
- 63447
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- Define general somatic sensation and special somatic sensation
- Describe the structures and functions of general somatic senses
- Explain how the structures of the eye modulate and assist with the detection of light by photoreceptors.
- Explain how the structures of the ear modulate and assist with the detection of sound by hair cells.
- Describe the structures of the vestibular apparatus and their role in equilibrium and balance.
- Describe the receptors and supporting cells responsible for chemoreception in taste and in smell.
- Trace the pathways from sensory receptors to their cerebral processing regions.
The somatic sensory system includes all the afferent, sensory receptors from the skin, skeletal muscles, joints and special senses which are responsible for our conscious perception of the environment.
Our somatic senses make us aware of our surroundings or state of our body through peripheral sensory receptors. These receptors send sensory information through cranial and spinal nerves to the central nervous system. The neurons of the central nervous system need to process the information, a step called integration. Once processed, if a motor response is required, the neurons of the central nervous system will send a signal to skeletal muscles to move.
In this chapter, we will examine the sensory components of the somatic nervous system. For the sensory input, we will look at sensory receptors of general and special senses and how the sensory information is sent to the CNS.
Figure \(\PageIndex{1}\): Back pain. Pain is detected by the class of receptors called nociceptors that detect potentially damaging stimuli that might cause us harm. Pain in muscles and joints is stimulated by thermal, mechanical, or chemical stimuli, which often results in poor localization and dull pain sensation. (Image credit: "laminectomy in Iran2" by Ermateb is licensed under CC BY-NC 4.0.)
In the United States the incidence of back pain differs by demographic characteristics (CDC, 2021):
- The percentage of adults with back pain increased with age, from 28.4% for those aged 18–29 and 35.2% for those aged 30–44 to 44.3% for those aged 45–64 and 45.6% for those aged 65 and over.
- Women (40.6%) were more likely to experience back pain than men (37.2%).
- Estimates of back pain differed among non-Hispanic white (42.7%), non-Hispanic black (35.8%), Hispanic (31.2%), and non-Hispanic Asian (24.5%) adults.
- The percentage of adults with back pain decreased as family income increased, from 44.8% in adults with income less than 100% of the federal poverty level (FPL) to 37.6% in adults with income 200% or more of FPL.
Contributors and Attributions
OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at https://openstax.org/books/anatomy-and-physiology