used terms for planes of orientation or planes of section in neuroanatomy are "sagittal", "transverse" or "coronal", and "axial" or "horizontal". Again in this case, the situation is different for swimming, creeping or quadrupedal (prone) animals than for Man, or other erect species, due to the changed position of the axis. Due to the axial brain flexures, no section plane ever achieves a complete section series in a selected plane, because some sections inevitably result cut oblique or even perpendicular to it, as they pass through the flexures. Experience allows to discern the portions that result cut as desired. A mid-sagittal plane divides the body and brain into left and right halves; sagittal sections, in general, are parallel to this median plane, moving along the medial-lateral dimension (see the image above). The term sagittal refers etymologically to the median suture between the right and left parietal bones of the cranium, known classically as sagittal suture, because it looks roughly like an arrow by its confluence with other sutures (sagitta; arrow in Latin). A section plane orthogonal to the axis of any elongated form in principle is held to be transverse (e.g., a transverse section of a finger or of the vertebral column); if there is no length axis, there is no way to define such sections, or there are infinite possibilities. Therefore, transverse body sections in vertebrates are parallel to the ribs, which are orthogonal to the vertebral column, which represents the body axis both in animals and man. The brain also has an intrinsic longitudinal axis – that of the primordial elongated neural tube – which becomes largely vertical with the erect posture of Man, similarly as the body axis, except at its rostral end, as commented above. This explains that transverse spinal cord sections are roughly parallel to our ribs, or to the ground. However, this is only true for the spinal cord and the brainstem, since the forebrain end of the neural axis bends crook-like during early morphogenesis into the chiasmatic hypothalamus, where it ends; the orientation of true transverse sections accordingly changes, and is no longer parallel to the ribs and ground, but perpendicular to them; lack of awareness of this morphologic brain peculiarity (present in all vertebrate brains without exceptions) has caused and still causes much erroneous thinking on forebrain brain parts. Acknowledging the singularity of rostral transverse sections, tradition has introduced a different descriptor