What is the difference between a swath and a sling?

A sling is used to hold and support an injured limb, typically an arm. However, on its own, a sling does not restrict movement in all directions. A second securement - known as a swath, is therefore used.

In the context of an arm sling, a swath is a piece of cloth wrapped over the sling and humerus, around the torso and under the opposite shoulder. This reduces movement of the injured arm in the transverse plane much better than with the sling alone.