What is tangential lighting?

This is a form of "side lighting" at an angle in order to best see small movement on the body, observable detail, and decrease shadow. (i.e.- to assess the strength of a carotid pulse, side lighting (tangential) may be used to inspect the skin raising with the pulse.) This also is the most commonly used to allow a surgeon best visual accuity of the infinite details in the structure being operated on. Tangential is used as "direct" would be used in "direct lighting". It may also concern the light itself. Tangential lights have several light sources, reflective posterior surfaces, and are convex in shape. This facilitates the collective beams into a single beam, as with a tangent. This beam is then aimed in a specific location. In the O.R., these lights suspend from the ceiling and can be moved on an axis to allow the surgeon better viewing of the incision site.