Your Sense of Orientation
 |
| Your Sense of Orientation |
There are two components to our sense of orientation: kinaesthetic sensors and vestibular organs.
Kinaesthetic sensors provide information about your body’s spatial position, and the movement of your joints and muscles. Special sensors in the mobile joints of the skeleton provide information on the motion of single joints, and the relative motion of sets of related joints. The shoulder is most sensitive to detecting small motions.
The wrist is next most sensitive, then the knuckle of the index finger. The ankle is the joint least sensitive to detecting small motions. The brain receives information from these sensors and uses it to determine the direction and the movement of your limbs in space.
For controlled motion, you also need information on the position and orientation of your whole body in space. In all mammals, vestibular organs located in the inner ears provide information on position and orientation. A vestibular organ is a tiny sac filled with fluid. It is lined with cilia (fine sensory hairs), and contains small crystals of calcium carbonate. Both gravity and acceleration in a straight line can force the crystals into the cilia, causing them to bend and send neural impulses to the cerebellum and the medulla. The vestibular organ also includes two fluid-filled loops at approximate right angles to each other. If your head moves in a circular motion, fluid in these loops flows and the cilia are bent, sending more neural impulses to the brain that correspond to the rotation of your head.
Visual input provides a backup check on the orientation and motion of your body.
The vestibular system can provide signals to help you interpret how your body is moving during most everyday activities. Even the repeated action of jogging presents no difficulty. However, large repeated motions, or motions in which the visual and vestibular systems provide conflicting information, can lead to motion sickness. Over time, most individuals eventually become habituated to an over stimulated vestibular system. If you spend enough time at sea, your seasickness will gradually disappear.
Our sense organs are highly specialized organs for collecting information about our environment. However, they are not mechanical machines that make absolute measurements, and they tire under constant stimulation. Organic sensors are best at monitoring changing conditions within their normal range of operation.
Raw input from your senses is filtered so that irrelevant data is disregarded. The remaining input is interpreted and constantly analyzed for danger factors, for emotional factors, and for practical information related to your current situation.
This filtering and interpretative activity occurs in your sub-conscious mind before the results are passed on to your conscious mind for consideration.
Your senses provide you with a continuous update on the state of your immediate physical environment.
