a substance secreted in a glandular sac under the skin of the abdomen of the male musk deer, having a strong odor, and used in perfumery. 2. an artificial imitation of the substance. 3. a similar secretion of other animals, as the civet, muskrat, and otter. 4. the odor of musk or some similar odor.
Lens: The lens is a clear part of the eye behind the iris that helps to focus light, or an image, on the retina. Macula: The macula is the small, sensitive area of the retina that gives central. vision. It is located in the center of the retina. Optic nerve: The optic nerve is the largest sensory nerve of the eye. It. carries impulses for sight from the retina to the brain. Pupil: The pupil is the opening at the center of the iris. The iris adjusts the size. of the pupil and controls the amount of light that can enter the eye.
Anatomy [edit]. The optic nerve is a cable connection that transmits images from the retina to the brain. It consists of over one million retinal ganglion cell axons. The optic nerve head, or optic disc is the anterior end of the nerve that is in the eye and hence is visible with an ophthalmoscope.It is located nasally and slightly inferior to the macula of the eye.ptic disc drusen (ODD) or optic nerve head drusen (ONHD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells.