Isometric exercises for the cervical spine are recommended by many doctors to gently strengthen the deep stabilizing muscles.
Isometric training means that muscles are contracted without changing their length. There is no movement in the area of training but the muscle is contracted through pushing or pulling (for example against a wall). It is only a change of the muscle tension. A couple of different physical therapies use these technique.
Often only the own body weight is used, for example you can train the pectoral muscle by pushing your hands together in front of your chest.
The advantages of isometric exercises are:
you don’t need much time for the exercises
you don’t need any other things like weights
the difficulty of the exercises can vary depending on the individuals needs
also bed bound patients can do them
Exercises I do for my cervical spine are:
I push with my head against my hand and hold it for some seconds. To the front, both sides, and back.