The Pacinian corpuscles are sensory preceptors that are found in many areas of the body, with their greatest density occurring in areas that are more sensitive to touch, such as the fingertips. Those Pacinian corpuscles that are found within a joint or joint capsule convey information to the central nervous system regarding changes in the positioning of the joint. When Pacinian corpuscles, which are also called lamellar corpuscles, are deformed by pressure, they cause action potentials or nerve impulses to occur in the free nerve ending embedded within them.
One of the four major mechanoreceptors, the Pacinian corpuscles are approximately 1 millimeter long, oval-shaped, and are wrapped in a layer of connective tissue. There is an inner core in the center of the structure that holds a myelinated nerve ending. Surrounding the core are layers of flattened cells resembling the layers of an onion. These layers, or lamellae, are extremely sensitive to pressure and vibration. When deformed, they cause the nerve ending embedded within the core to bend. The physical deformation of the nerve ending's plasma membrane causes it to emit positive sodium ions that, after reaching a certain threshold, are transferred as an impulse along the axon.
The Pacinian corpuscles are especially sensitive to vibration, a property that makes them capable of determining the textures of surfaces coming in contact with the skin. The rapidly adapting and highly sensitive mechanoreceptors were named after Filippo Pacini, the Italian anatomist who first discovered them.