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.
Within the eye there are many elements that work together with the nervous system and the eye muscles to create vision. Light flows through the cornea and the pupil of the globe (eyeball) onto the lens before it is projected onto the retina in the back of the eye.