For other uses, see Non-fiction (disambiguation). Non-fiction or nonfiction is content (sometimes, in the form of a story) whose creator, in good faith, assumes responsibility for the truth or accuracy of the events, people, and/or information presented. In contrast, a story whose creator explicitly leaves open if and how the work refers to reality is usually classified as fiction.
For each eye, six muscles work together to control eye position and movement. Two extraocular muscles, the medial rectus and lateral rectus, work together to control horizontal eye movements (Figure 8.1, left). 1  Contraction of the medial rectus pulls the eye towards the nose (adduction or medial movement).
The central control of eye movement can be distilled into the principle types of functions. These include voluntary, conjugate horizontal gaze (looking side-to-side); voluntary, conjugate vertical gaze (looking up and down); smoothly tracking objects; convergence; and eye movements resulting from head movements.