For the forward edge of a sail, see parts of a sail.

In sailing the parts of a sail have common terminology for each corner and edge of the sail.

Tack is a term used in sailing that has different meanings in different contexts, variously a part of a sail, and an alignment with the wind.

The microscopic anatomy of each spine varies from base to tip, indicating where it was embedded in the muscles of the back and where it was exposed as part of a sail.