Trigger points (“X” on the images below) in several different face and neck muscles can cause jaw pain. Here are some of the most commonly afflicted.
Masseter. A trigger-point approach to treating TMJ usually involves a first look at the masseter. This is the big muscle that protrudes over the jawbone, commonly the area that people massage when describing jaw pain. Like other face and neck muscles, the masseter can develop trigger points from teeth clenching and grinding, excessive gum chewing or nail biting, and poor body mechanics. But this muscle more than others is affected by stress.
"The masseter muscles are among the first to contract in persons who are in a state of extreme emotional tension, intense determination, or desperation, and they remain contracted for abnormally long periods of time," says Janet Travell in her book "Myofascial Pain and Dysfunction: The Trigger Point Manual."
Trigger points in the masseter can refer pain to the cheeks, lower jaw, upper and lower molar teeth, up into the eyebrow, and deep into the ear and around the temporomandibular joint (see picture above). Since the main function of the masseter muscle is to elevate the mandible (the lower jawbone), cases where the person has a hard time opening his mouth usually indicate trigger points in the masseter. One-sided tinnitus can be another clue.
The pain patterns for trigger points in the temporalis muscle resemble those of the masseter (see picture at left). However, these patients tend to complain more explicitly of headaches, usually on the side of the head and along the eyebrow or behind the eye. The tooth pain associated with temporalis trigger points is felt in the upper teeth and not exclusively in the molars.
Medial and lateral pterygoid. These little muscles, when affected by trigger points, pack a powerful punch. They both refer pain directly to the temporomandibular joint region. Pain from medial pterygoid trigger points is concentrated directly in front of the ear and spreads downward along the jaw and upper outside of the neck. These trigger points also can cause throat pain and difficulty swallowing. Pain from lateral pterygoid trigger points, in addition to the temporomandibular joint area in front of the ear, radiates higher on the face, on the maxilla (upper jaw). Travell says trigger points in the lateral pterygoid “are the chief myofascial source of referred pain felt in the TMJ area.”
The sternocleidomastoid, or SCM, has two divisions, both of which can cause TMJ symptoms when affected by trigger points (see picture at right). The sternal division primarily leads to pain above the eyebrow that spreads across the cheek and into the jaw. Pain may also appear at the back and top of the head. Trigger points in the clavicular division produce pain that’s more concentrated in and around the ear, as well as frontal headaches.
Pain from trapezius trigger points spans from the arm to the head. One particular referral pattern, from trigger points in the upper part of the muscle, can mimic some symptoms of TMJ (see picture at left). In addition to lower jaw pain and temporal headaches, these trigger points can cause intense pain behind and below the ear that extends down to where the neck meets the shoulder. This is especially common in people who work at computers all day, as sustained elevation of the shoulders can produce and exacerbate trigger points in the trapezius.
Considered one of the facial muscles, the platysma is a sheath-like muscle that extends from around the jaw down over the clavicle. Trigger points in the platysma cause a diffuse pricking pain over the lower jaw. The pain is felt more on the surface, at the skin level, rather than deep in the muscle.