The term plane of section refers to a cross-sectional view of the brain. The meanings of the terms sagittal plane, coronal plane and horizontal plane vary depending on the position of the head regarded as standard by the author. In BrainInfo they are defined in accordance with Gray-1918a. The body is assumed to be in the standard anatomical position, i.e., standing erect and facing forward. sagittal plane are planes of section parallel to the median plane, "the vertical antero-posterior plane passing through the center of the trunk. This plane will pass approximately through the sagittal suture of the skull, and hence any plane parallel to is termed a sagittal plane. A vertical plane at right angles to the median plane passes, roughly speaking, through the central part of the coronal suture or through a line parallel to it; such a plane is known as a frontal plane or sometimes as a coronal plane. A plane at right angles to both the median and frontal planes is termed a transverse plane." A common synonym for the transverse plane used in BrainInfo is "horizontal plane". For a thorough review and discussion of the use of these and related terms in clinical and comparative neuroanatomy, see Anthoney-1994.