Somatic Afferent or Sensory Neurons

Somatic afferents (or sensory neurons) are nerve fibers, part of the somatic nervous system (also includes somatic efferent neurons), which transmit sensory information from the body to the central nervous system (CNS). They connect to peripheral receptors (peripheral process), extend into the CNS (central process), and are located in the posterior root ganglion (a cluster of transmitting sensory neuron’s somas). Two somatic afferent pathways:

• General somatic afferent (GSA): These fibers, found in most spinal nerves, carry impulses from the body’s surface — pain, temperature, and touch, as well as impulses from deeper structures, such as muscles, joints, and tendons — to the brain. 
• Special somatic afferent (SSA): These systems involve specialized receptor organs stimulated by changes in the external environment: the eyeball stimulated by light and the inner ear by air waves — both through the cranial nerve.