Pacinian

Pacinian corpuscles, also known as Pacinian receptors, are specialized, encapsulated mechanoreceptors found in the skin and other tissues, notably in deep dermal and subcutaneous layers, as well as in joints, periosteum, and mesentery. They primarily detect mechanical stimuli such as high-frequency vibration and rapid changes in pressure.

Structure and innervation: Each corpuscle is a large, ovoid capsule containing numerous concentric lamellae of connective tissue surrounding a single nerve ending. The nerve ending is usually associated with a myelinated Aβ fiber that traverses the lamellated capsule. The onion-like lamellae and the encapsulated arrangement enable sensitive transmission of dynamic mechanical signals. Pacinian corpuscles exhibit rapid adaptation, responding strongly to changes in stimulus rather than to sustained pressure.

Physiology and sensitivity: Pacinian corpuscles are rapidly adapting receptors best suited to detect dynamic events, including onset and offset of pressure and high-frequency vibrations. They are most responsive to frequencies in the higher range (roughly around 250 Hz) and show reduced response to constant, unchanging pressure.

Distribution: They are particularly abundant in glabrous skin of the fingertips, palms, and soles, but are also found in deeper tissues such as joints, periosteum, and mesentery. Compared with some other mechanoreceptors, they are relatively sparse near the surface of the skin.

History: The corpuscles are named after the Italian anatomist Filippo Pacini, who first described them in the 19th century. In older literature they may be referred to as Vater-Pacinian corpuscles.

See also: mechanoreceptors, Meissner corpuscle, Ruffini ending, Merkel disc.