Several terms are used to identify the orientation and location of neural structures. The orientation nomenclature is quite simple in organisms such as fish and reptiles, which have a linear nervous system. For these animals, ventral (Latin for “belly”) is oriented toward the ground, dorsal (Latin for “back”) toward the sky, rostral (Latin for “beak”) toward the snout, and caudal (Latin for “tail) toward the tail (eFig. 9.5). Because humans are bipedal and maintain an erect posture, the nervous system makes an obligatory bend of 80 to 90 degrees at the midbrain–diencephalic junction. Because of this, directional references such as ventral, dorsal, rostral, and caudal have different meanings along different locations of the CNS structures (eFig. 9.6A). An additional set of terms that remain constant in their reference to orientation of nervous system structures are anterior, posterior, superior, and inferior.