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!
Rods and cones in the retina of the eye receive information from the visual fields and, through intermediary cells, convey this input to retinal ganglion cells. Ganglion cell axons converge at the optic disc, pass through the sclera, and form the optic nerve.