The Cutaneous Senses

Rebecca Hulgan

The skin is the heaviest organ in the human body, it is also hasthe largest surface area. The skin is often called the epidermis; itkeeps the body warm, protects it from bacteria, and keeps body fluidsfrom escaping. This layer is actually made up of tough dead skincells. Below the epidermis is the dermis; it is within these twolayers that we find the mechanoreceptors: receptors that respond tomechanical stimulation (pressure, stretching, vibration). They arewhat we use to feel.

Mechanoreceptors in the Skin (4 Types)

Most people can use their touch senses to identify common objectswithin one to two seconds. People use exploratory procedures (EP) todetermine what the object is. The types of EP's used depend on theobject qualities. People use mainly lateral motion and contourfollowing to judge texture and enclosure and contour following tojudge exact shape.

Different parts of the body are more sensitive than others. Thepointer finger is the most sensitive part of the body. The chartbelow shows touch thresholds. The higher the threshold, the lesssensitive that part is.


One Type of Touch Illusion

Phantom Limb - some people who have had a limb removed continue toexperience the limb.

This perception is so convincing that people have actually triedusing the phantom limb.

For many the limb moves with the body, swinging while walking.

For some the limb is paralyzed, fixed in one position.

It is not uncommon to experience pain in the phantom limb.

Researchers do not know what exactly causes sensation in thephantom limb.