Top definition. Musk. Though technically the name for the secretion of the male musk deer, musk is most often used as the name for the scent of arousal in both men and women, as actual musk is used in perfumes and colognes. Generally causes arousal for both genders, as it is a secondary sex characteristic.
These photoreceptors are called the rods and cones. Rods are called rods because under the microscope, they are shaped like, of all things, a rod. Finally, those pesky scientists named a structure for what it actually looks like as opposed to someone's unpronounceable last name!
Ultimately it reaches the retina, which is the light-sensing structure of the eye. The retina contains two types of cells, called rods and cones. Rods handle vision in low light, and cones handle color vision and detail. When light contacts these two types of cells, a series of complex chemical reactions occurs. The chemical that is formed (activated rhodopsin) creates electrical impulses in the optic nerve.