Father Pacini corpuscles

Father Pacini corpuscles belong to the mechanoreceptors in the skin that are particularly suitable for the detection of vibrations. A thickening serves as a sensor at the unmarked ends of the otherwise medullary nerves. There is a thickening that can reach a diameter of up to 2 millimeters. The thickening consists of 40 to 60 concentrically superimposed lamellar layers, which are enclosed on the outside by a connective tissue capsule.

What is the father Pacini corpse?

Vater-Pacini corpuscles are named after the German anatomist Abraham Vater (18th century) and the Italian anatomist Philippo Pacini (19th century). Together with 4 other types of mechanoreceptors, they belong to the touch sensors, each type of which is optimized for the detection of specific stimuli.

The Vater-Pacini corpuscles are the only tactile sensors in the subcutis because, according to their specialization, they can cover a relatively wide field. They are quick to adapt, that is, they specialize in rapid stimulus changes. Their main task is to detect vibrations using sensors. Due to their extremely fast adaptation, they are optimized for vibrations in the frequency range of 300 Hz (oscillations per second), a frequency that is already perceived as a deep tone by the human ear.

The sensor head of the Vater-Pacini corpuscles consists of a thickening on the unmarked nerve endings of afferent neurons, the rest of which is surrounded by a myelin sheath. Father Pacini corpuscles are found more frequently in the palms and soles of the feet as well as on the fingertips. Further accumulations can be found in the periosteum, in the pancreas, in other organs in the lower abdomen, in the urinary bladder and in the vaginal area.

Anatomy & structure

Vater-Pacini corpuscles mark the unmarked end part of sensory nerves, the rest of which are surrounded by a medullary sheath. The Vater-Pacini corpuscles consist of a thickening of the nerve endings, which arise from a concentric - onion skin-like - layering of up to 60 lamellae.

The lamellae are made up of flattened Schwann cells that normally envelop neurons without mycelium. The individual lamellae are separated from each other by an extremely thin film of interstitial body fluid. In the inner space of the sensor heads there is a fluid-filled space in which the free end of the nerve can move. On the outside, the tactile bodies are enclosed by a connective tissue capsule. The anatomical structure of the Vater-Pacini corpuscles makes them very quickly adapting touch sensors.

A deformation of only a few micrometers causes an influx of sodium ions, which trigger an action potential. The sensors hardly react to slow deformations that last longer. They specialize in rapidly changing pressure deformations, such as those typically caused by vibrations.

Function & tasks

Vater-Pacini corpuscles, together with Merkel cell receptors, Krause corpuscles, Meissner corpuscles and Ruffini corpuscles, form a network of skin sensors, which are referred to as the sense of touch. In order to give the responsible brain areas a more complete picture, the sense of touch is supplemented by temperature and pain sensors. The brain is not only able to create a situation report from the millions of sensor reports, but the received and processed reports can also be converted into conscious or unconscious instructions.

For example, high temperature reports lead to an unconscious opening of the sweat pores of the skin in order to increase the evaporative cooling for a cooling effect. Vater-Pacini corpuscles specialize in rapid changes in pressure and changes in direction of the effects of pressure, so that they can perceive vibrations very well. You can even detect weak vibrations up to several hundred oscillations, i.e. vibrations that are already well in the audible range, which begins at around 200 Hz. Vater-Pacini corpuscles react not only to vibrations that act on the skin from outside, but also to changes in pressure on the skin when the hands slide over a rough surface.

This means that they not only serve as part of a warning device of possible impending injuries, but are also part of the sense of touch for better haptic detection of a surface. At the same time, they complement the fine sensory recording of lightweights such as spiders and insects, which crawl over the skin and can potentially be dangerous.

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Diseases

As with all sensory services that are recorded through the formation of nervous action potentials and passed on in the form of electrical impulses via ganglia and other "clearing points" such as the thalamus, functional disorders can also occur in the Vater-Pacini bodies.

A reduced performance of the tactile bodies can be based on mechanical injuries in the affected skin areas or on infections or tumors that lead to serious physiological changes. Much more often, however, the transmission paths of the nervous impulses, i.e. the neurons themselves or the implementation of the nervous impulses at the synapses, are affected. Only rarely are disturbances in superficial sensitivity restricted to Vater-Pacini corpuscles. As a rule, such disturbances extend to all skin sensors in a certain area. The perception can refer not only to a weakening (hypaesthesia), but also to an increase (hyperesthesia) of the sensations.

Weakening of the surface sensitivity can often be observed, which can often be attributed to circulatory disorders (ischemia) and thus to insufficient supply of the afferent sensory nerves. Ischemia in this area is often an indicator of serious metabolic disorders such as diabetes. In addition to metabolic disorders, hypaesthesia up to complete numbness (numbness) can also be caused by mechanical pressure exerted on the nerves. The mechanical pressure can typically arise in bottlenecks that serve to pass nerves and blood vessels to joints, such as the carpal tunnel on the wrist.