What it is

Apex and hook are the names of the two defender spots between the cornerback and the middle of the field. The apex is the first underneath defender inside the cornerback. The hook is the second one, closer to the middle.

In a game

Coaches use these names for the spot, not for the player. The apex is responsible for the #2 receiver and is often a nickelback, a linebacker or a safety who has moved closer to the line. The hook usually lines up at linebacker depth and is responsible for the #3 receiver, often a running back, and for the middle of the field underneath.

More detail

Using the names of the spots keeps the rules simple. When a safety or a nickelback plays the apex, he follows exactly the same rules as a linebacker would, so the defense can change its personnel without rewriting its coverage. Short calls such as “push” or “under” are often shouted between the apex and the hook, because they decide who picks up a running back or a crossing route.

The diagram

1. The cornerback covers the #1 receiver.
2. The apex lines up inside the cornerback and takes #2.
3. The hook lines up next and takes #3 or the middle underneath.