The ability to detect changes in the environment is critical to survival. The human body has various organs for this purpose. The nose senses odors in the environment, the tongue senses tastes, and the eyes are important for visual sense. The ears serve two functions-hearing and equilibrium.

Each of these special senses works in concert with the nervous system to assist the body in coping with environmental changes experienced throughout the day. A medical assistant should understand the special senses in order to test distance and near visual acuity, color vision, and hearing. Knowledge of the anatomy of the eye and ear is essential when performing irrigation or instillation of these structures.