The Somatic Senses

The somatic (general) senses collect information about cutaneous sensations (tactile sensations on the surface of the skin) and proprioceptive sensations. The following stimuli are detected:
  • Tactile stimuli are detected by mechanoreceptors and produce sensations of touch and pressure:
  • Merkel discs are receptors with free nerve endings that detect surface pressure (light touch). They are located deep in the epidermis.
  • Root hair plexuses are receptors with free nerve endings that surround hair follicles and detect hair movement.
  • Corpuscles of touch (Meissner's corpuscles) are receptors with encapsulated nerve endings located in the dermal paillae (near the surface) of the skin that detect surface pressure (light touch).
  • Pacinian corpuscles are encapsulated nerve receptors that detect deep pressure and are located in the subcutaneous layer (below the skin).
  • Thermal stimuli are detected by free nerve ending thermoreceptors sensitive to heat or cold.
  • Pain stimuli are detected by free nerve ending nociceptors.
  • Proprioceptive stimuli are detected by the following receptors:
  • Muscle spindles are mechanoreceptors located in skeletal muscles. They consist of specialized skeletal muscle fibers enclosed in a spindle‐shaped capsule made of connective tissue.
  • Golgi tendon organs are mechanoreceptors located at the junctions of tendons and muscles.
  • Joint kinesthetic receptors are mechanoreceptors located in synovial joints.