The document discusses the olfactory nerve (cranial nerve I), which is responsible for smell. It has four neurons - olfactory receptors in the nose, mitral/tufted cells in the olfactory bulb, neurons in the primary olfactory cortex, and neurons in the secondary olfactory cortex. The olfactory pathway projects from the nose to these cortical areas. Testing smell can localize pathology and determine laterality. Interpretations include describing degrees of smell ability or aberration and identifying potential causes of anosmia.