Pacinian corpuscles are mechanoreceptors located throughout the body, including the dermal layer of the skin, tendons and joint capsules, as well as the mesentery surrounding the intestines. Their job is to mediate the tactile sensations of deep pressure and vibration.
Under a microscope, Pacinian corpuscles resemble tiny onion bulbs. When these structures are deformed by mechanical stimuli, they fire action potentials, which the brain ultimately interprets as deep touch.
The skin contains other mechanoreceptors, including Meissner corpuscles, Merkel endings and Ruffini endings. They are collectively responsible for detecting light touch and moderate pressure. The axons of mechanoreceptors are heavily myelinated, enabling these neurons to quickly transmit action potentials. Of all neurons responsible for detecting tactile information, only proprioceptors, which include the muscle spindles and Golgi tendon organs, transmit signals faster. In contrast, the nerve fibers carrying temperature sensation are lightly myelinated, while the C fibers that transmit pain signals are completely unmyelinated.
Mechanoreceptors send their signals to the brain via white matter tracts in the spinal cord called the dorsal columns. Pain and temperature signals reach the brain via a different route, called the spinothalamic tract.
Pacinian corpuscles were named in honor of the Italian anatomist Filippo Pacini, who discovered them around the year 1875.