Muscle of the week: Longus colli
The longus colli muscle provides stability to the neck much like the "core muscles" of the lumbar spine do.
Here is a picture of the longus colli to the left.
This muscle is fairly difficult to isolate as the larger neck muscles attempt to dominate the longus colli. To attempt to isolate this muscle do this:
Make sure to keep your larger side muscles, the sternocleidomastoid muscles relaxed.