In anatomy and zoology, the cortex (plural cortices) is the outermost (or superficial) layer of an organ. Organs with well-defined cortical layers include kidneys, adrenal glands, ovaries, the thymus, and portions of the brain, including the cerebral cortex, the best-known of all cortices.
The cerebral cortex is typically described as comprising three parts: the sensory, motor, and association areas. These sensory areas receive and process information from the senses. The senses of vision, audition, and touch are served by the primary visual cortex, the primary auditory cortex, and primary somatosensory cortex. The cerebellar cortex is the thin gray surface layer of the cerebellum, consisting of an outer molecular layer or stratum moleculare, a single layer of Purkinje cells (the ganglionic layer), and an inner granular layer or stratum granulosum. The cortex is the outer surface of the cerebrum and is composed of gray matter.
The motor areas are located in both hemispheres of the cerebral cortex. Two areas of the cortex are commonly referred to as motor: the primary motor cortex, which executes voluntary movements; and the supplementary motor areas and premotor cortex, which select voluntary movements. In addition, motor functions have been attributed to the posterior parietal cortex, which guides voluntary movements; and the dorsolateral prefrontal cortex, which decides which voluntary movements to make according to higher-order instructions, rules, and self-generated thoughts.