Question

What are para axial lines

Answer 1

An axial line is the line between two adjacent dermatomes that are not represented by immediately adjacent spinal levels. Although dermatomes are shown to be discrete segments on dermatomal maps (like in the image opposite), they are in fact not; adjacent dermatomes overlap with one another.

Answer 2

The paraxial approximation can be used to derive simple equations involving lenses. A statement of the approximation involves the optical axis, which is a line that passes through the center of each lens and is oriented in a direction normal to the surface of the lens (at the center).