Question

Tactile Localization

Why does it make sense to be able to localize stimuli better with some areas of skin that with others? Give specific examples in your explanation and discuss how we use the different regions that were tested [approximately two paragraphs] Location: palm of hand, back of hand, fingertip, anterior forearm, back of neck, anterior leg.

Answer 1

When you touch something, the mechanoreceptors accept the sensation just below the surface of the skin. Dense amount of mechanoreceptors are present in certain areas of the body like fingertips, palm of hand, anterior of forearm and back of neck.

The outermost layer of skin is epidermis which is made of dead cells. Underneath the epidermis is dermis made of fat and connective tissue. The sense of touch is controlled by a huge network of nerve endings and touch receptors in the skin known as the somatosensory system.which detect cold, hot, smooth, rough, pressure, tickle, itch, pain, vibrations, and more. Within the somatosensory system, there are four main types of receptors: mechanoreceptors, thermoreceptors, pain receptors, and proprioceptors. After stimulating the skin surface, activity travels through the thalamus to primary somatosensory cortex (S1). The somatosensory cortex is organized topographically, such that (with a few exceptions) adjacent locations of the body are represented.

Merkel’s disks, Meissner’s corpuscles, Ruffini’s corpuscles, and Pacinian corpuscles are the four types of mechanoreceptors whose only function is to perceive indentions and vibrations of the skin. The most sensitive mechanoreceptors, Merkel’s disks and Meissner’s corpuscles, are found in the very top layers of the dermis and epidermis and are generally found in non-hairy skin such as the palms, lips, tongue, soles of feet, fingertips, eyelids, and the face.

Ruffini’s corpuscles and Pacinian corpuscles are located deeper in the in the dermis and along joints, tendons, and muscles. These mechanoreceptors can feel sensations such as vibrations traveling down bones and tendons, rotational movement of limbs, and the stretching of skin. This greatly aids your ability to do physical activities such as walking and playing ball. Hence according to the density of the receptors located in each area of the body, the response to the sensation by that area increases.