Somatic senses: the bodily foundation for perception and movement

In studying the human body, we usually associate the senses with those that connect us to the outside world: sight, hearing, taste, and smell. However, there is another set of senses, just as essential, that operate from within and through our skin. These are known as somatic senses, forming a complex network of receptors that allow us to perceive our environment in a more intimate way: from the pressure of an object in your hand to the exact position of your arms with your eyes closed.

Each of these senses responds to specific types of sensory cells distributed throughout the body, and together they build a detailed perception of our physical and spatial state. In this article, we’ll take a brief but clear look at the main somatic senses and their functions in everyday life.

Touch

The sense of touch allows us to perceive mechanical stimuli through the skin, such as pressure, vibration, or contact. This information is sent to the brain via different types of skin receptors, each specialized in a particular kind of stimulus: light pressure, deep pressure, sustained pressure, hair displacement (hair follicle bending), and vibrations.

In daily life, touch is the somatic sense we use most consciously: from feeling the keys under our fingers to detecting the texture of fabric.

Note: The hair follicle is the dermal structure that surrounds the root of the hair. It houses stem cells and is responsible for hair growth. It is one of the most dynamic structures in the human body.

Thermoception

Thermoception is the ability to detect temperature changes in the environment or in the body. Thermoreceptors in the skin respond specifically to thermal stimuli, distinguishing between cold and heat.

When we feel the sun burning the back of our neck or the cooling effect of an ice cube on our mouth, these receptors are at work. It is important to note that when temperatures reach extremes (either very high or very low), pain receptors also come into play, generating sensations of burning or freezing.

In addition to the skin, our internal organs also have thermoreceptors, which help the brain monitor and regulate body temperature at all times.

Nociception

Nociception is the sense responsible for detecting pain, a vital signal that something is wrong in our body. Nociceptors are specialized nerve endings that identify various harmful stimuli, such as mechanical, thermal, or chemical damage.

There are different types of nociceptors, each associated with a specific type of pain: sharp pain, burning pain, chemical irritation, joint or deep pain, as well as related sensations like tingling and itching. Pain, although unpleasant, serves an indispensable protective function: alerting the body to potential injuries or physiological imbalances.

Proprioception

Proprioception is the sense that allows us to perceive the position, movement, and orientation of our body in space, even with our eyes closed. This sensory system is essential for motor coordination and balance.

It consists of two main types of receptors:

• Muscle and tendon receptors, which detect stretching and tension. These allow the brain to locate our limbs in space and adjust their movement precisely.

• Joint receptors, found in the cartilage of the joints. They provide information about load, rotation, and sliding, allowing the brain to calculate the speed and direction of movement.

Without proprioception, even simple actions—like walking or writing—would be impossible to perform smoothly.

Balance (vestibular sense)

Unlike other somatic senses, balance does not rely on receptors distributed throughout the body but on a highly specialized system located in the inner ear: the vestibular apparatus. This system detects changes in head position and body movement, allowing us to maintain orientation and stability.

Although it may seem counterintuitive, the sense of balance is considered part of the somatic senses due to its essential role in bodily perception and, above all, its evolutionary antiquity.

The vestibular system is present in all vertebrates and has existed for over 500 million years, making it one of the oldest senses in the animal kingdom.

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