# Skin Tension Lines --- **Skin tension lines** are lines that can be drawn on the [[skin]] that indicate the overall orientation of the underlying [[collagen]] fibers. This is very important for wound [[healing]] or surgical incision planning, because the direction the injury happens relative to a tension line greatly effect the shape of the wound. If the injury is parallel along a tension line, it can remain relatively closed on its own. However, if the injury is perpendicular to the tension line, it severs the [[collagen]] (and [[elastic fiber|elastic]]) fibers and causes them to retract, pulling the edges of the wound open. ![[skin tension lines.png]] ___