Body processes

Epicritic Sensitivity – Function, Task & Diseases

Epicritical Sensitivity

The epicritic sensitivity is a perception system of the skin and is also called tactile sensitivity or fine perception . It is closely related to proprioception . Disorders of epicritic sensitivity are often caused by peripheral or central nerve damage.

What is Epicritic Sensitivity?

The human skin sense has different perceptual qualities, which are summarized as surface sensitivity. One of them is the epicritic sensitivity. As such, the discriminatory perceptions of vibration, pressure and touch are understood, which are also known as fine perception. In addition, epicritic sensitivity includes perceptions of the proprioceptive positional sense and is thus involved in both interoception of internal stimuli and exteroception of external stimuli.

The epicritic sensitivity works with various sensory cells that translate a stimulus into the language of the central nervous system . The epicritical receptors are either exteroceptors or interoceptors. The exteroceptors of epicritic sensitivity are primarily mechanoreceptors for gathering information about the location or fine-tuning of a touch. Proprioceptors such as the muscle spindles and tendon spindles are relevant as epicritical interoceptors, which serve to obtain information about the position of the muscles and joints.

Protopathic sensitivity is to be distinguished from epicritic sensitivity . This second quality of perception of the skin sense provides information on temperature and pain via thermoreceptors and nociceptors and is also referred to as predominantly exteroceptive coarse perception.

As part of tactile perception , epicritic sensitivity, in contrast to protopathic sensitivity, means the ability to perceive spatially close touch stimuli as individual stimuli. Fine perception plays a role for both tactile and haptic perception , in the sense of passive and active tactile perception.

Function & task

The epicritic perceptual system is also called the discriminating system of the skin. The protopathic system of the skin sense, on the other hand, corresponds to a protective system. Epicritic perception can be broken down into passive touch perception and active exploratory perception.All proprioceptive structures of the system are passive touch-perceptual structures. The first place for the perception of epicritical information are the receptors . In this context, mechanoceptors such as pressoreceptors and baroreceptors are distinguished from proprioceptors such as muscle spindles. The mechanoceptors are primarily concerned with pressure perception. Proprioceptors are responsible for self-awareness. Beroreceptors are located, for example, in the wall of blood vessels and are involved in the enteroceptive regulation of blood pressure .

Mechanoreceptors are mainly divided into SA, RA and PC receptors. The most important SA receptors are the Merkel cells, the Ruffini corpuscles and the Pinkus-Iggo tactile discs for pressure perception. Significant RA receptors are the Meissner bodies , the hair follicle sensors, and the Krause end bulbs for touch perception. The PC receptors responsible for vibration sensation are primarily the Vater-Pacini corpuscles and the Golgi-Mazzoni corpuscles.

In connection with proprioception, enteroceptive receptors are distinguished from purely proprioceptive receptors. Automatically controlled bodily processes such as the urge to urinate , the urge to defecate , the cough reflex or the filling of the auricles are regulated via enteroceptive epicritical receptors in the bladder , the gastrointestinal tract or the cardiovascular system .

For all exteroceptive stimuli, all epicritical information is transmitted via the dorsal strands of the spinal cord . The protopathic receptors of the skin sense, on the other hand, transmit their information via the anterior spinocerebellar tract or posterior|posterior spinocerebellar tract to the cerebellum . The posterior strand pathways as an afferent information pathway of epicritic sensitivity run uncrossed.

The gracile fasciculus is responsible for the information that affects the lower extremities. The cuneatus fasciculus, on the other hand, directs the epicritic information of the upper extremities. The first neuron switches to the second neuron in the gracile or cuneate nucleus of the brainstem. After this switching, the pathways continue as lemniscus medialis and cross within the decusatio lemniscorum. In the thalamus , they are switched to a third neuron, which then transports the epicritical information to the postcentral gyrus.

As part of the tactile perception, the epicritical sensitivity in terms of touch sharpness is determined using a two-point discrimination threshold. In young people, the tactile sensitivity of fine perception is about 1.5 millimeters at the fingertip. In older people, it is sometimes only four millimeters. On the back, the tactile sensitivity of fine perception is physiologically the lowest and amounts to a few centimetres.

Diseases & Ailments

The most important task of the epicritic system is the evaluation and differentiation of tactile impressions and touch impressions. Disorders of the epicritic system are expressed primarily in the inability to distinguish between touch and touch.One of the most common causes of surface sensitivity disorders is damage to peripheral or central nerves. A lack of sensory integration can also be responsible for disturbances in epicritic sensitivity. A sensory integration disorder goes back to predisposition and is expressed in the inability to combine different sensory impressions with each other. On the other hand, it can result from a lack of physical practice in childhood.

The ability to combine different sensory impressions is particularly important for the near senses such as the epicritic system and can be increased if necessary with a disposition. Epicritical sensory disturbances are expressed either as hyperesthesia or as anesthesia . Hyperesthesia corresponds to an increased perception or hypersensitivity to touch stimuli and can assume painful proportions.

Hyperaesthesia often occurs as a result of acute or chronic irritation of nerve structures, for example after operations or other interventions. Those affected often show a tactile defense, which is expressed in the avoidance of touching.

The opposite phenomenon is anesthesia, which amounts to an insensibility. Localized anesthesia is found, for example, in the case of peripheral polypathies in a specific part of the body, such as can be caused by poisoning , diabetes or certain infections . Just as often, local anesthetics can be traced back to damage to the central nervous system as part of a neurological disease such as multiple sclerosis , a stroke or a spinal cord infarction . Traumatic damage to the central nervous system can also be a possible cause. The same applies to tumor diseasesof the central nervous system.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.