Poikkileikkaus

Poikkileikkaus, meaning cross-section, is a view obtained by cutting through an object to reveal interior features not visible from the outside. The term combines poikki "across" and leikkaus "cutting" and is widely used in Finnish technical and scientific language. A poikkileikkaus is typically produced as a section view in drawings or as a slice in imaging or analysis, illustrating what lies beneath the exterior along a defined plane.

The concept is used across disciplines. In anatomy and medicine, cross-sections (axial, sagittal, coronal) show tissues and organs and are central to medical imaging techniques such as CT and MRI, which display internal structures as stacked slices. In botany and plant science, a vertical or horizontal poikkileikkaus of stems, roots, or leaves reveals tissue organization such as epidermis, cortex, vascular tissue, and xylem/phloem. In geology and earth science, cross-sections depict subsurface stratigraphy, faulting, and mineralogy along a transect. In engineering and architecture, poikkileikkaus refers to a section view of a component or building, exposing interior features, material transitions, and reinforcement; drawings guide fabrication and assembly.

In mathematics and geometry, a cross-section is the intersection of a solid with a plane, used to study shapes and properties of three-dimensional objects. Interpreting a poikkileikkaus typically requires labeling of the cutting plane, scale, and the materials or tissues represented.