"Through peripheral and ambient vision, the brain senses the body's movement, orientation in space and relationship to objects in the environment. Vision also detects the stability of a surface or object. For example, seeing a swaying rope bridge causes a different response in the body than seeing a sturdy pillared one. When the eyes focus on a steady object, the vestibular system of the inner ear can orient the head vertically, horizontally and spatially. This helps stabilize the body."
The nervous system has complex and vital functions. One of these functions is proprioception. Proprioception literally means "one's own perception”, or “sense of self.”. It is the sense of the relative position of one’s own neighboring parts of the body. (Mosby, 1994) Proprioception is the sense through which the body perceives its own motion and also gives the brain information about where parts of the body are located in relation to each other. (Proprioception n.d.) Proprioception provides information to the brain about the body’s movement, pressure, movement, weight acting on the limbs, and limbs’ complex interactions. The brain takes in the proprioceptive information and makes a current map of the body. The body’s self awareness maps derived from this proprioceptive input not only guide body movement, they also help sense the size and shape of objects and measure the shape of space surrounding the body. (Smetacek & Mechsner, 2004) During the learning of any new skill or activity that uses the body it is usually necessary to become familiar with new proprioceptive tasks. (Proprioception n.d.)
The proprioceptive awareness of the orientation of the body comes from sensory receptors in the joints, tendons, and muscles. The sensory receptors are called proprioceptors. Proprioceptors sense the status of physical reactions within the body, such as muscle length, deep pressure, joint angle or tendon tension. Signals from proprioceptors about the body’s condition are sent by nerves through the spinal cord to the brain. The proprioceptors send constant updates to the nervous system’s internal maps of body position. (Smetacek & Mechsner, 2004) Sensory information from proprioceptors, in muscles and tendons are used by the motor system as information to guide gait, postural adjustments and control of movements like walking.
Information from proprioceptors is normally combined with information from the vestibular system and its receptors. The vestibular system senses gravitational acceleration and changes in velocity from movements of the head, visual, auditory, and tactile receptors. Human orientation and coordination is managed and run by three independent sensory systems: proprioception, vision, and the vestibular system. Proprioception is sense of self, and vision gives us information about the world around us. The vestibular system, based in the organs of the inner ear, gives the body a sense balance, momentum, and it aids in guiding the eyes. The signals from these senses are tightly integrated that it is difficult to draw lines at their borders of function or even to separate them.
"The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals, situated in the vestibulum in the inner ear (Figure 1). As our movements consist of rotations and translations, the vestibular system comprises two components: the semicircular canal system, which indicate rotational movements; and the otoliths, which indicate linear accelerations. The vestibular system sends signals primarily to the neural structures that control our eye movements, and to the muscles that keep us upright . The projections to the former provide the anatomical basis of the vestibulo-ocular reflex, which is required for clear vision; and the projections to the muscles that control our posture are necessary to keep us upright."
Mosby’s Medical (1994) Nursing and Allied Health Dictionary, Fourth Edition, Mosby-Year Book, p. 1285
Proprioception (n.d.) Retrieved from Wikipedia, the Free Encyclopedia: http://en.wikipedia.org/wiki/Proprioception
Smetacek and F. Mechsner (2004). Cognitive Science: On Proprioception. Retrieved from http://scienceweek.com/2004/sb041210-6.htm