7. The Visual System Revised August 8, 2007 The objectives of
this chapter are to: - Describe the organization of the visual
system. - Describe the neuroanatomy of two important visual
reflexes, the pupillary light reflex and the near response. It
is assumed that you have already studied the gross anatomy and
histology of the eye. I. The Visual Pathway Eyeball and retina:
The visual pathway begins in the eyeball (fig 7a). Light waves
pass through the cornea and lens to impinge on the retina. The
receptors for the visual system are specialized neurons called
photoreceptors, rods and cones, which are located in the retina.
The retina contains several cell types that are arranged in
distinct layers. The outermost layer, i.e., the layer adjacent
to the choroid, is the retinal pigment epithelium (#52211). What
is the origin of these cells (fig 7b)? What is their functional
significance? Embedded in the pigment epithelium (#9927) (c) are
the processes (b) of the photoreceptor cells whose cell bodies
are shown in (a