It is impossible to formulate a meaningful mental model of how traumatic brain injury (TBI) can disrupt the physical substrates of vision without having detailed knowledge of the visual system. The visual system is one of the most complex and well studied in the brain. This chapter discusses general brain anatomy and subsequent modular organization and connectivity. The brain has two solid components and four anatomical parts. The cortex is at the top of the hierarchy for complex processing of visual information and integrating it with other sensory, motor, cognitive, and social/emotional domains. Different cortical nodes include the primary unimodal association, multimodal association and supramodal cortices and are connected among themselves with the subcortical areas to form distributed neural networks to perform specific functions, including vision. The purpose of the optical system is to present a clear and undistorted image on the retina. Vision begins in the retina, the retinogeniculocortical system.