The sense of touch (somatosensation) relies on a diverse network of specialized sensory neurons called mechanoreceptors. These receptors convert mechanical forces like pressure and vibration into electrical signals the brain interprets. Among these, the Pacinian corpuscle is a distinct and highly-tuned sensor, playing a unique role in the perception of dynamic touch.
Defining the Pacinian Corpuscle
A Pacinian corpuscle, also known as a lamellar or Vater-Pacini corpuscle, is a large, encapsulated sensory nerve ending. These structures are typically oval or spherical, sometimes reaching over a millimeter in length. Each corpuscle consists of a single nerve fiber surrounded by a complex, layered capsule.
These receptors are located deep within the body’s tissues, not near the skin surface. In the skin, they are situated in the deep dermis and subcutaneous tissue, concentrated in the hands and feet. They are also found internally in joint capsules, the periosteum of bone, mesenteries, and organs like the pancreas.
Primary Sensory Function
The Pacinian corpuscle detects high-frequency vibration and transient, deep pressure. They act as sensitive vibration detectors, optimally tuned around 250 Hertz (Hz), though they can detect frequencies from 20 Hz up to 1000 Hz. This specific tuning allows them to perceive subtle, high-frequency oscillations that travel through tissues.
The corpuscles are rapidly adapting mechanoreceptors, meaning they only generate a signal when a stimulus begins or ends, not while it is maintained. For instance, they fire impulses when deep pressure is applied and again when it is removed, remaining silent during continuous application. This rapid adaptation makes them ideal for sensing change, movement, and the vibratory nature of contact rather than static pressure.
The Unique Structure and Mechanism
The function of the Pacinian corpuscle is directly linked to its physical architecture, which is often likened to a small onion. It features many concentric layers of connective tissue, called lamellae, surrounding a central, unmyelinated nerve axon terminal. These layers, which can number up to 60, are separated by fluid-filled spaces and enclosed by a connective tissue sheath.
This layered, fluid-filled capsule serves as a mechanical filter that is the physical basis for rapid adaptation. When static pressure is applied, the force is initially transmitted to the central nerve ending, causing a brief deformation that opens mechanically-gated ion channels. However, the fluid and the viscoelastic lamellae quickly redistribute and dampen the sustained pressure, relieving the stress on the nerve ending.
Only dynamic, high-frequency changes, such as vibrations, are effectively transmitted through the layers to the central nerve fiber. The repeated, rapid mechanical deformation of the axon terminal by the oscillating pressure repeatedly opens and closes the ion channels. This results in the continuous generation of action potentials for the duration of the vibration. This process, known as mechanotransduction, converts the physical energy of the movement into an electrical nerve impulse.
Role in Overall Touch Sensation
The high-frequency detection capability of Pacinian corpuscles refines our sense of touch and interaction with objects. Their ability to sense vibrations is important for perceiving fine texture, such as distinguishing between smooth and rough materials. This occurs because movement across a surface generates high-frequency vibrations in the skin corresponding to the material’s texture.
These receptors are also important for manipulating tools and objects. When holding a vibrating tool, the corpuscles detect subtle transmitted vibrations, providing feedback about the interaction. Furthermore, when located near joints and deep fascia, their sensitivity to deep, transient pressure contributes to proprioception—the body’s sense of position and movement in space. This information helps monitor and control limb movements.