Question

Briefly present the significance of Somatosensory System. Explain and give examples in your own words.

Answer 1

Summary:-

The somatosensory system is the part of the sensory system.

It concerned with the conscious perception of touch, pressure, pain, temperature, position, movement, and vibration, which arise from the muscles, joints and skin.

The somatosensory system is a 3 neuron system that relays sensations detected in the periphery and conveys them via pathways through the spinal cord, brainstem, and thalamic relay nuclei to the sensory cortex in the parietal lobe.

Significance:-

Somatosensory system informs us about the objects in our external environment through touch (i.e., physical contact with skin),

and about the position and movement of our body parts (proprioception) through the stimulation of muscle and joints.

The somatosensory systems also regulate the temperature of the body, external objects and environment, and provide information about painful, itchy and tickling stimuli.

The sensory information processed by the somatosensory systems travels along different anatomical pathways depending on the information carried.

For example:- The posterior column-medial lemniscal pathway carries discriminative touch and proprioceptive information from the body, and the main sensory trigeminal pathway carries this information from the face. Whereas, the spinothalamic pathways carry crude touch, pain and temperature information from the body, and the spinal trigeminal pathway carries this information from the face.

The somatosensory systems process information about the several modalities of somatic sensation (i.e., pain, temperature, touch, proprioception).

Temperature:-

When a somatosensory neuron is stimulated naturally (e.g., by skin warming) or artificially (e.g., by electrical stimulation of the neuron), the sensation perceived is specific to the information normally processed by the neuron (i.e., warm skin). Consequently, a "warm" somatosensory neuron will not respond to cooling of the skin or to a touch stimulus that does not "warm" the skin.

Tactile Stimuli:-

Tactile stimuli are external forces in physical contact with the skin that give rise to the sensations of touch, pressure, flutter, or vibration.

An initial clinical examination of discriminative touch often involves testing the vibratory sense by applying a 128 Hz tuning fork over a bony prominence.

Proprioceptive Stimuli:-

Proprioceptive stimuli are internal forces that are generated by the position or movement of a body part. Static forces on the joints, muscles and tendons, which maintain limb position against the force of gravity, indicate the position of a limb. The movement of a limb is indicated by dynamic changes in the forces applied to muscles, tendons and joints.

An initial clinical examination of proprioception often involves testing the position sense by having the patient, with eyes closed, touch one finger with another after the target finger has been moved.

Proprioception is critical for maintaining posture and balance. Somatosensory proprioceptive cues are combined with vestibular proprioceptive cues and visual cues to control motor responses to changes in body or head position.

During a clinical examination, the Romberg test requires the patient to maintain balance while standing with feet together and eyes closed.

Sharp Cutting Pain Stimuli:-

Painful (nociceptive) stimuli are tissue damaging sources of energy that may be external or internal to the body surface. Sharp, cutting pain is the sensation elicited on initial contact with the painful stimulus. The sensation of dull, burning pain may follow as a consequence of tissue inflammation.

An initial clinical examination of the pain sense often involves testing sharp, cutting pain sensitivity by asking the patient, who has her/his eyes closed, what they feel when pricked with a pin.