Neuroanatomy V: The Somatosensory System

The somatosensory system is often confused as being the system of touch, however the system is a little more complicated than this; whilst this is the system of the body under which touch does fall, it is an umbrella system as such which helps to monitor the bodies internal and external processes such as temperature (regulates galvanic skin response - sweat levels) as well as touch and feel.

The first point for one to note when learning about this system is that it revolves around the skin, the skin and its nerve endings which communicate with the central nervous system through the spinal cord in various ways. Yet before this, we should refer to kinesthetics, this word refers simply to the recognition of movement and body position, this is important for it communicates with the skeletal muscles of the movement system.

There are two main types of skin, hairy skin which covers most of the exposed body exempting the palms of the hands and soles of the feet, which are covered by smooth or glavarous skin. It is this smooth skin which is the sensitive parts of the body, this is because they come in contact most directly with objects, think about it, when you want to identify an object through one of those things in a museum, you do not try fit your stomach, back, neck, shoulder or leg through to identify what the object is. Instead you use your hands, it is by using the palms to identify the object by more tender nerves.

As I started by saying, the communication comes from the skins surface (the dermis) communicating with the nerves below the dermis in the epidermis and further, travelling to the spinal nerves which meet with the tragmental nerve OR fifth cranial nerve. More is explained in my saying that further communication is made with the brain via the dorsal root ganglion of this nerve and travels through the white matter of the spinal cord, ascends to the lower medulla and then the lemniscus and finally reaches the primary somatosensory cortex.

Of course, the two systems differ between the communicating of pain and temperature and the system communicating tickles and caresses, which travels from the spinal cord up to the medulla and through to the thalamus and finally reaching the primary somatosensory cortex.