Muscle:Medial Pterygoid

Medial pterygoid is a deep masticatory muscle whose trigger points (TrPs) produce a poorly circumscribed pattern of referred pain involving the mouth, throat, hard palate, and ear — a pattern distinctly more diffuse than that of the lateral pterygoid. Its TrPs are almost never found in isolation; they develop in association with functionally related muscles, particularly the lateral pterygoid and masseter.

Anatomy

The medial pterygoid has two heads:

• Deep head — arises from the medial surface of the lateral pterygoid plate of the sphenoid bone
• Superficial head — arises from the tuberosity of the maxilla and pyramidal process of the palatine bone

Both heads insert into the medial surface of the ramus and angle of the mandible, forming a pterygoid sling with the masseter on the lateral side.

Primary actions: Elevation of the mandible (jaw closing); contributes to protrusion and contralateral excursion of the mandible.

Innervation: Medial pterygoid nerve, a branch of the mandibular nerve (V3).

Main synergists: Masseter and temporalis (jaw elevation).

Referred Pain Patterns

TrPs in the medial pterygoid refer pain in poorly circumscribed regions to:

• Tongue, pharynx, and hard palate
• Below and behind the TMJ, including deep in the ear
• Anterior to the tragus and along the ramus
• Underneath the ear

Pain is generally more diffuse than that referred from the lateral pterygoid. Pain is not referred to the teeth — this distinguishes medial pterygoid referral from masseter and temporalis referral.

Ear Stuffiness — Barohypoacusis

Stuffiness of the ear is a characteristic symptom of medial pterygoid TrPs. The mechanism:

• In order for the tensor veli palatini muscle to dilate the eustachian tube, it must push the adjacent medial pterygoid muscle and interposed fascia aside
• In the resting state, the presence of the medial pterygoid helps keep the eustachian tube closed
• Tense myofascial TrP bands in the medial pterygoid may block the opening action of the tensor veli palatini on the eustachian tube
• This produces barohypoacusis — ear stuffiness, reduced pressure equalisation

Swallowing Difficulty

Patients may complain of soreness inside the throat and painful swallowing. A characteristic compensatory pattern is observed: when attempting to swallow, the patient extends the neck and pushes the tongue forward, apparently trying to overcome a restriction in the forward movement of the mandible.

Aggravating Factors

Pain is increased by:

• Attempts to open the mouth wide
• Chewing food
• Clenching the teeth

Activation and Perpetuating Factors

• Bruxism (lateral grinding of the teeth)
• Teeth clenching
• Anxiety and emotional tension
• Thumb sucking after infancy
• Excessive gum chewing
• Sustained contraction from medial pterygoid spasm activated reflexly by cellulitis in the pterygomandibular space
• Co-activation with lateral pterygoid and masseter TrPs — medial pterygoid rarely develops TrPs in isolation

Clinical Examination

Mandibular Range of Motion

With active medial pterygoid TrPs, mandibular opening is usually obviously restricted — the jaw aperture may not admit two knuckles.

During opening, unilateral medial pterygoid involvement is variably reported as deviating the mandible toward the opposite side, toward the same side, or not at all. The most consistent finding is that deviation due mainly to shortening of this muscle is most marked toward the contralateral side as the mandible approaches maximum opening. The direction of deviation depends greatly on how severely other protruding, retruding, and lateral-deviating muscles are involved.

For the full mandibular ROM assessment and TMJ screening protocol see Pain:TMJ_Screening_Examination.

Trigger Point Examination

Intraoral Palpation — Central TrPs

The preferred technique for central TrPs in the midmuscle region:

1. Patient is supine; jaw drops open as far as comfortable to take up slack in the muscle
2. Gloved index finger enters the mouth with the pad facing outward
3. Slide the finger over the molar teeth until it encounters the bony anterior edge of the ramus of the mandible, which lies behind and lateral to the last molar tooth
4. The belly of the medial pterygoid lies immediately posterior to this bony edge
5. Palpate for taut bands and exquisite spot tenderness

To confirm muscle identification, ask the patient to alternately clench and relax against a block or cork placed between the teeth while palpating — the changes in tissue tension clearly identify the medial pterygoid.

Advantages of intraoral palpation:

• Only a thin layer of mucosa separates the palpating finger from the muscle
• Taut bands are more readily identified and less pressure is required to elicit TrP tenderness than for many muscles

Managing the Gag Reflex

Intraoral palpation through the pharyngeal mucosa can trigger the gag reflex. The following techniques reduce it:

• Ask the patient to exhale fully or take a deep breath and hold it during examination
• Tap the ipsilateral temporalis muscle to provide sensory distraction
• Ask the patient to curl the tip of the tongue as far as possible down the throat behind the molar teeth on the opposite side — the harder the patient forces the tongue backward and down, the less sensitive the reflex becomes
• If necessary, apply a quick-acting topical anaesthetic spray (30 seconds onset) to anaesthetise the pharyngeal mucosa in hypersensitive individuals

Extraoral Palpation — Mandibular Attachment TrPs

To palpate for TrPs at the mandibular attachment from outside the mouth:

1. Tilt the patient's head slightly toward the side to be palpated to slacken tissues and improve access
2. Press one finger upward at the angle of the mandible along its inner (medial) surface
3. The firm mass approximately 1 cm above the angle of the mandible, just within reach of the finger, is the inferior part of the mandibular attachment of the muscle

Nerve Entrapment

The medial pterygoid may entrap the chorda tympani portion of the lingual nerve as it passes between the medial pterygoid muscle and the mandible.

Clinical presentation: An extremely bitter metallic taste interfering with normal oral functioning.

Management note: Temporary splints and fixed bridges that open the bite approximately 3 mm have been reported to resolve this entrapment by reducing compression of the nerve.

Stretch Technique — Resisted Jaw Opening

Resisted jaw opening is an augmented stretch technique based on reciprocal inhibition, useful for releasing the medial pterygoid and all jaw elevator muscles simultaneously:

1. The clinician applies light resistance to jaw opening with one hand under the chin
2. The patient opens the jaw slowly against this resistance
3. Activation of the jaw depressors (digastric, suprahyoid, and infrahyoid muscles) reciprocally inhibits the elevation function of the medial pterygoid and all other jaw elevators
4. This can be taught as a home exercise — the patient supplies their own resistance

Differential Diagnosis

Condition	Distinguishing features
Lateral pterygoid TrPs	Lateral pterygoid pain is more circumscribed; resisted jaw closing pain is specific to lateral pterygoid; medial pterygoid pain is more diffuse and involves throat and hard palate
Masseter TrPs	Masseter refers to teeth (all stimuli hypersensitivity); medial pterygoid does not refer to teeth; masseter restriction is usually more severe
Tongue TrP	Pain in the throat deep behind the angle of the jaw can be caused by a TrP in the posterior lateral part of the tongue on the same side — suspect if no medial pterygoid TrP activity is found
Persistent dysphagia after treatment	If swallowing difficulty persists after medial pterygoid TrP inactivation, examine the sternocleidomastoid, digastric, and possibly the longus capitis and longus colli for TrPs
Cellulitis of pterygomandibular space	Causes reflex medial pterygoid spasm and restricted opening — trismus with systemic signs; refer for urgent dental/medical assessment

Treatment

Trigger Point Release

• Intraoral ischemic compression: Sustained pressure on TrPs via intraoral palpation as described above
• Intraoral spray and stretch: Vapocoolant spray applied intraorally over the muscle region during jaw opening stretch
• Resisted jaw opening: Reciprocal inhibition technique as described above — useful as both a clinical technique and home exercise
• Refer to dental/oral medicine if restricted opening does not respond to conservative treatment

Address Co-active Muscles

Medial pterygoid TrPs rarely occur in isolation. Assess and treat lateral pterygoid and masseter TrPs concurrently.

Satellite Trigger Points

• Lateral pterygoid — most common co-active muscle
• Masseter — functionally related synergist
• Temporalis — jaw elevator synergist
• Sternocleidomastoid — examine if dysphagia persists after medial pterygoid treatment
• Digastric — examine if dysphagia persists

Related Pages

• Pain:Ear_and_TMJ — Diagnostic algorithm including medial pterygoid
• Pain:Throat_and_Front_of_Neck — Medial pterygoid as source of throat pain
• Pain:TMJ_Screening_Examination — Full TMJ screening protocol
• Muscle:Lateral_Pterygoid — Most common co-active muscle
• Muscle:Masseter — Functionally related synergist

References

• Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1: The Upper Half of Body. 2nd ed. Baltimore: Williams & Wilkins; 1999. Chapter 9.