The word oblique comes from the Latin “oblicuus”. In geometry, an oblique figure is one that is not perpendicular to a plane, or to a particular direction, in short, it is one that is not straight. For example, in geometry there are several oblique figures such as the oblique angle, this is the one that is not straight; then the oblique cylinder whose bases are not perpendicular to its generatrix; oblique triangle which is not a right triangle; then there is the oblique cone whose base is not perpendicular to its generatrix either; and finally, the oblique, which is a geometric element that is neither parallel nor perpendicular to another given element. As an adjective it is used to describe something that is diagonal, lopsided, or inclined from the horizontal.

This term is also applied to some muscles of the body specifically to those of the abdomen, it is called external oblique or greater, this is found from the last eight ribs and its function is to compress and support the abdominal viscera, and allow rotation and trunk flexion. Next is the internal or minor oblique, which is below the major oblique, they are a pair, wide and flattened that are composed of fleshy follicles and aponeurosis, and their function is the same, to support the abdominal viscera and allow rotation and flexion of the trunk. On the other hand are the two oblique muscles of the eye, the lower and the upper; the lower one passes under the eye and its function is to make it rotate up and out. And finally the upper one whose function is the same as the lower muscle.