National Associaltion of Myofascial Trigger Point Therapists - Symptom Checker
Masseter
This is the technical name of the muscle being described. This name may be used to find additional information in any medical resource. Masseter
A group of muscles generally denotes muscles of the same function and may share a common attachment point. Jaw Elevators
Muscle function, in this definition, is what the muscle could do if it was to contract by itself with the body in anatomical position. This is a general definition of muscle function. For more information on how muscles work together on the body please refer to a physiology or functional anatomy text.

masseter functions to elevate (close) and retract the jaw.
A description of where a Myofascial Trigger Point may produce pain in the body. This area is generally located away from the trigger point.

The masseter is divided into two layers, a superficial and a deep layer.

The superficial layer refers pain to the lower jaw, teeth, gums, and sometimes into the maxilla.  TrPs in other areas of this layer of the masseter will refer pain to the upper molar teeth, gums, and maxilla.  Pain may also be referred in an arc shapeabove the eyebrow and may appear in the lower jaw.  TrPs in       the masseter, or temporalis, may cause tooth hypersensitivities to heat, cold, percussion, or occlusal pressure.

The deep layer may refer diffuse pain to the midcheek area and sometimes to the area of the temporomandibular joint (TMJ). Pain may be referred deep into the ear as well as tinnitus (ear ringing).  The tinnitus is usually described as being “low roaring”.
A description of the symptoms a person may experience with trigger points in the muscle being described.

A person with TrPs in the masseter, particularly the superficial layer, will most likely complain of restriction of jaw opening. Most are unaware that their jaws do not open sufficiently, especially if eating food is not difficult.  Pain is very common
and usually occurs as described above in the “pain pattern” section.

Unilateral tinnitus may be associated with the upper portion of the deep masseter as well as earache of unexplained origin.
   

 A list of possible diseases that fit the information derived from examination of a patient.

  1. Tinnitus of neurological origin.
  2. Pulpitis.
  3. Apical inflammation of the periodontal ligament.
  4. Anteriorly displaced discs of the TMJs.
  5. Trismus.

A list of activities or positions that may either CAUSE a trigger point to manifest or PROLONG a pain condition respectively.

  1. Excessive head forward posture.
  2. Chronic mouth breathing, such as through a surgical mask, or nasal obstruction.
  3. Crushing ice or nuts with the teeth.
  4. Teeth clenching or bruxism (teeth grinding).
  5. Gum chewing, nail biting, or clamping the teeth on a tobacco pipe.
  6. Emotional tension or anxiety that causes clenching of the teeth.
  7. Prolonged over stretching as with a dental procedure.
  8. Direct trauma to the masseter.
  9. Whiplash type injuries, as experienced in a motor vehicle accident.

A corrective action is usually a modification of daily routine which will reduce stress on the affected muscle(s) in a person with myofascial trigger points.

  1. A person should be instructed to take steps to stop retrusive bruxism (teeth grinding) and restore breathing through the nose, instead of the mouth.
  2. Head forward posture should be corrected to reduce masseter activity.
  3. Find solutions for emotional stress and anxiety.
  4. Other myofascial TrPs must be deactivated if they exist in other muscles, such as the sternocleidomastoid (SCM), trapezius, and any other muscles that refer to the area of the masseter.
  5. Intermittent breaks should be taken during long dental procedures.
  6. Avoid crushing ice or nuts with the teeth.
  7. Avoid chewing gum.
 

References : 
Simons DG, Travell JG, Simons LS, Myofascial Pain and Dysfunction: The Trigger Point Manual, vol 1, 2nd Ed. Baltimore: Williams and Wilkins, 1999.

Travell JG, Simons DG, Myofascial Pain and Dysfunction, vol 2. Baltimore: Williams & Wilkins, 1992.

This information is not intended to diagnose, treat, or cure any disease.  A proper diagnosis should be sought from a licensed health care provider.