Cutaneous receptors are classified as rapidly adapting (RA) or slowly adapting (SA). The four types of receptor that contribute to touch are the Merkel cell (SA-1), The Ruffini organ (SA-II), the Meissner corpuscle (RA-I) and the Pacinian corpuscle (RA-II). The output of these receptors is transmitted by primary neurons in the dorsal root ganglion through relay neurons in the cuneate nucleus and thalamus to the primary somatosensory cortex (SI). Brodmann's area 3b is the portion of SI devoted to cutaneous mechanoreceptive stimuli. It is organized topographically, with further subdivision by...

Cutaneous receptors are classified as rapidly adapting (RA) or slowly adapting (SA). The four types of receptor that contribute to touch are the Merkel cell (SA-1), The Ruffini organ (SA-II), the Meissner corpuscle (RA-I) and the Pacinian corpuscle (RA-II). The output of these receptors is transmitted by primary neurons in the dorsal root ganglion through relay neurons in the cuneate nucleus and thalamus to the primary somatosensory cortex (SI). Brodmann's area 3b is the portion of SI devoted to cutaneous mechanoreceptive stimuli. It is organized topographically, with further subdivision by sensory modality. Individual sensory channels for SA I, RA, and PC activity thus extend from skin to cortex, where they terminate in modality-specific cortical columns.