What is the function of the somatosensory system

what is the function of the somatosensory system

What Is the Function of the Somatosensory Cortex?

Apr 13,  · Anatomically speaking, the somatosensory system is a network of neurons that help humans recognize objects, discriminate textures, generate sensory-motor feedback and exchange social cues. Sensory neurons relay peripheral sensations such as pain, pressure, movement or temperature from the skin to the brain. The somatosensory system is distributed throughout all major parts of our body. It is responsible for sensing touch, temperature, posture, limb position, and more. It includes both sensory receptor neurons in the periphery (eg., skin, muscle, and organs) and deeper neurons within the .

The cerebral cortex is the outermost layer of the human brain. The somatosensory and somatomotor cortexes are two adjoining narrow bands of the topmost central area of the brain, stretching roughly from ear to what did romans eat for breakfast lunch and dinner. The function of the somatosensory cortex is to receive and interpret most of the human sense of touch.

Skin what is the function of the somatosensory system the largest organ of the human body. Among its main functions are to interact with the physical environment by sensing temperature, pressure and thr. Millions of nerve cells, called receptors, are imbedded in the skin to record this information. Together, all of these parts comprise what is commonly referred as the somatosensory system.

One area is called the primary somatosensory cortex. It is integrally connected funchion another part of the brain called the thalamuswhich is believed to coordinate the sense of touch and sense of space with muscle movement.

There is also an area called what is the function of the somatosensory system secondary somatosensory cortex, which extends deeper into the brain along the surface of its fissures, or crevasse-like folds. The function of this area is to receive and react to the sensation of pain, and also to keep the brain slmatosensory if continuous attention to touch is deemed necessary.

Other functions here include the evaluation tne size, shape and texture of touch or pressure. One of the most studied and well understood areas of the somatosensory cortex is the postcentral gyrus. It is, essentially, a one-to-one mapping of the human skin, the entire surface area of the body. This somatic mapping of the brain is called a homonculus.

The main function of the somatosensory cortex is to simply identify the location of stimulated skin. It receives the signals from several different types of nerve cells. They include mechanoreceptors that detect pressure, thermoreceptors that register temperature, and fknction that signal physical trauma or pain.

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Physiology

Aug 12,  · The somatosensory system also includes receptors and neurons that convey information about body position and movement to the brain. These proprioceptors are housed in muscle, bone, and tendons and respond to stretch and contraction, tension and release. Examples of different types of receptors located under our skin. Jan 29,  · The main function of the somatosensory cortex is to simply identify the location of stimulated skin. It receives the signals from several different types of nerve cells. They include mechanoreceptors that detect pressure, thermoreceptors that register temperature, and nociceptors that signal physical trauma or pain. The somatosensory system is comprised of elements of the peripheral nervous system and central nervous system that serve the modalities of touch, vibration, temperature, pain and kinesthesia. .

The somatosensory system is composed of the neurons that make sensing touch, temperature, and position in space possible. Describe how the somatosensory system is composed of neurons that make sensing touch, temperature, and position in space possible. The somatosensory system is distributed throughout all major parts of our body.

It is responsible for sensing touch, temperature, posture, limb position, and more. It includes both sensory receptor neurons in the periphery eg. A somatosensory pathway will typically consist of three neurons: primary, secondary, and tertiary. The primary somatosensory area of the human cortex is located in the postcentral gyrus of the parietal lobe. The postcentral gyrus is the location of the primary somatosensory area, the area of the cortex dedicated to the processing of touch information.

At this location there is a map of sensory space referred to as a sensory homunculus. The surface area of cortex dedicated to a body part correlates with the amount of somatosensory input from that area. For example, there is a large area of cortex devoted to sensation in the hands, while the back requires a much smaller area. Somatosensory information involved with proprioception and posture is processed in the cerebellum. Homunculus : Image representing the cortical sensory homunculus.

It shows how the anatomical portions of the body, such as the tongue, elbow, and hip, are mapped out on the homonculus. A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. For instance, in the periodontal ligament, there are mechanoreceptors that allow the jaw to relax when biting down on hard objects; the mesencephalic nucleus is responsible for this reflex.

There are also mechanoreceptors in hairy skin. The hair cells in the cochlea are the most sensitive mechanoreceptors, transducing air pressure waves into nerve signals sent to the brain. Cutaneous mechanoreceptors are located in the skin, like other cutaneous receptors. They provide the senses of touch, pressure, vibration, proprioception, and others. They can be categorized by morphology, by the type of sensation they perceive, and by the rate of adaptation.

Furthermore, each has a different receptive field:. The Ruffini ending Ruffini corpuscle or bulbous corpuscle is a class of slowly adapting mechanoreceptors thought to exist only in the glabrous dermis and subcutaneous tissue of humans.

It is named after Angelo Ruffini. This spindle-shaped receptor is sensitive to skin stretch, and contributes to the kinesthetic sense of and control of finger position and movement. It is believed to be useful for monitoring the slippage of objects along the surface of the skin, allowing the modulation of grip on an object.

Ruffini endings are located in the deep layers of the skin. They register mechanical information within joints, more specifically angle change, with a specificity of up to two degrees, as well as continuous pressure states. They also act as thermoreceptors that respond for a long time, such as holding hands with someone during a walk. In a case of a deep burn to the body, there will be no pain as these receptors will be burned off.

In particular, they have the highest sensitivity lowest threshold when sensing vibrations lower than 50 hertz. They are rapidly adaptive receptors. Pacinian corpuscles or lamellar corpuscles are responsible for sensitivity to vibration and pressure. The vibrational role may be used to detect surface texture, e.

Merkel nerve endings are mechanoreceptors found in the skin and mucosa of vertebrates that provide touch information to the brain. The information they provide are those regarding pressure and texture. Each ending consists of a Merkel cell in close apposition with an enlarged nerve terminal. This is sometimes referred to as a Merkel cell—neurite complex, or a Merkel disk receptor. A single afferent nerve fiber branches to innervate up to 90 such endings. They are classified as slowly adapting type I mechanoreceptors.

Describe how propioception is the sense of the position of parts of our body in a three dimensional space. Proprioception is the sense of the relative position of neighboring parts of the body and the strength of effort being employed in movement. It is distinguished from exteroception, perception of the outside world, and interoception, perception of pain, hunger, and the movement of internal organs, etc.

The initiation of proprioception is the activation of a proprioreceptor in the periphery. The proprioceptive sense is believed to be composed of information from sensory neurons located in the inner ear motion and orientation and in the stretch receptors located in the muscles and the joint-supporting ligaments stance.

Conscious proprioception is communicated by the posterior dorsal column—medial lemniscus pathway to the cerebrum. Unconscious proprioception is communicated primarily via the dorsal and ventral spinocerebellar tracts to the cerebellum. An unconscious reaction is seen in the human proprioceptive reflex, or Law of Righting. In the event that the body tilts in any direction, the person will cock their head back to level the eyes against the horizon.

This is seen even in infants as soon as they gain control of their neck muscles. This control comes from the cerebellum, the part of the brain that affects balance. Muscle spindles are sensory receptors within the belly of a muscle that primarily detect changes in the length of a muscle. They convey length information to the central nervous system via sensory neurons. This information can be processed by the brain to determine the position of body parts. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles.

Muscle spindle : Mammalian muscle spindle showing typical position in a muscle left , neuronal connections in spinal cord middle , and expanded schematic right. The spindle is a stretch receptor with its own motor supply consisting of several intrafusal muscle fibers. The sensory endings of a primary group Ia afferent and a secondary group II afferent coil around the non-contractile central portions of the intrafusal fibers.

The Golgi organ also called Golgi tendon organ, tendon organ, neurotendinous organ or neurotendinous spindle is a proprioceptive sensory receptor organ that is located at the insertion of skeletal muscle fibers onto the tendons of skeletal muscle.

It provides the sensory component of the Golgi tendon reflex. The Golgi organ should not be confused with the Golgi apparatus—an organelle in the eukaryotic cell —or the Golgi stain, which is a histologic stain for neuron cell bodies.

Golgi tendon organ : The Golgi tendon organ contributes to the Golgi tendon reflex and provides proprioceptive information about joint position. The Golgi tendon reflex is a normal component of the reflex arc of the peripheral nervous system.

In a Golgi tendon reflex, skeletal muscle contraction causes the agonist muscle to simultaneously lengthen and relax. This reflex is also called the inverse myotatic reflex, because it is the inverse of the stretch reflex. Although muscle tension is increasing during the contraction, alpha motor neurons in the spinal cord that supply the muscle are inhibited. However, antagonistic muscles are activated. The somatosensory pathway is composed of three neurons located in the dorsal root ganglion, the spinal cord, and the thalamus.

A somatosensory pathway will typically have three long neurons: primary, secondary, and tertiary. The first always has its cell body in the dorsal root ganglion of the spinal nerve. Dorsal root ganglion : Sensory nerves of a dorsal root ganglion are depicted entering the spinal cord. The axons of many of these neurons terminate in the thalamus, and others terminate in the reticular activating system or the cerebellum.

In the case of touch and certain types of pain, the third neuron has its cell body in the ventral posterior nucleus of the thalamus and ends in the postcentral gyrus of the parietal lobe. In the periphery, the somatosensory system detects various stimuli by sensory receptors, such as by mechanoreceptors for tactile sensation and nociceptors for pain sensation.

The sensory information touch, pain, temperature, etc. Generally, there is a correlation between the type of sensory modality detected and the type of afferent neuron involved.

For example, slow, thin, unmyelinated neurons conduct pain whereas faster, thicker, myelinated neurons conduct casual touch. In the spinal cord, the somatosensory system includes ascending pathways from the body to the brain. One major target within the brain is the postcentral gyrus in the cerebral cortex.

This is the target for neurons of the dorsal column—medial lemniscal pathway and the ventral spinothalamic pathway. Note that many ascending somatosensory pathways include synapses in either the thalamus or the reticular formation before they reach the cortex.

Other ascending pathways, particularly those involved with control of posture, are projected to the cerebellum, including the ventral and dorsal spinocerebellar tracts. Another important target for afferent somatosensory neurons that enter the spinal cord are those neurons involved with local segmental reflexes. Spinal nerve : The formation of the spinal nerve from the dorsal and ventral roots. The primary somatosensory area in the human cortex is located in the postcentral gyrus of the parietal lobe.

This is the main sensory receptive area for the sense of touch. Like other sensory areas, there is a map of sensory space called a homunculus at this location. Areas of this part of the human brain map to certain areas of the body, dependent on the amount or importance of somatosensory input from that area.

For example, there is a large area of cortex devoted to sensation in the hands, while the back has a much smaller area. Somatosensory information involved with proprioception and posture also target an entirely different part of the brain, the cerebellum.

This is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex; namely, the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body.

The thalamus is a midline symmetrical structure within the brain of vertebrates including humans; it is situated between the cerebral cortex and midbrain, and surrounds the third ventricle. Its function includes relaying sensory and motor signals to the cerebral cortex, along with the regulation of consciousness, sleep, and alertness. Thalamic nuclei : The ventral posterolateral nucleus receives sensory information from the body.

The cortical sensory homunculus is located in the postcentral gyrus and provides a representation of the body to the brain. A cortical homunculus is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex; it is the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body. There are two types of homunculus: sensory and motor.

Each one shows a representation of how much of its respective cortex innervates certain body parts. The primary somesthetic cortex sensory pertains to the signals within the postcentral gyrus coming from the thalamus, and the primary motor cortex pertains to signals within the precentral gyrus coming from the premotor area of the frontal lobes.

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