Clench Those Teeth
The Infrahyoids are made up of four muscles; three of which attach to the hyoid bone, the omohyoid, the sternohyoid and the thyrohyoid. They lie right over the trachea. The Infrahyoids, flex the neck and the Suprahyoids open the jaw.
The Platysma also opens the jaw. The anterior portion, the thickest part of the platysma muscle depresses the mandible when you strain leaving the mouth partially open.
The Temporal and powerful Masseter muscles close the jaw. When you are playing hard in sport you are slightly opening the airway and at the same time trying to close your mouth for protection from contact.
This is one of the many reasons it is important to wear a mouthguard during practice or a contest. As the mandible is depressed during straining, you are still able to clench your teeth against the high impact polymer material. You can do this with your jaw slightly pulled down as the mouthguard becomes a spacer. Clenching your teeth activates all the neck musculature to protect the head and stiffen the neck to dissipate force. The dissipation of force protects the athlete from concussions.
To strengthen the head and neck musculature in training you are faced with the same issue as if you were straining during play. Muscles are trying to open and close your jaw at the same time during each repetition. To take advantage of this and maximize your development, keep your teeth clenched while exercising the front of the neck on the 4 or 5 way neck machine as long as possible under high stress.
Setting the Pendulum Cam in any of the last four holes and clenching as you train will maximize the power of the hyoids and fully develop your head and neck muscles as you Get Strong.