← All Muscles

Lateral Pterygoid

Muscles

The lateral pterygoid is the only muscle of mastication that opens the jaw, attaching directly to the TMJ disc and condyle. Its dysfunction is central to TMJ disc displacement, making it the single most important muscle in understanding internal TMJ derangement.

Origin, Insertion, Action, Innervation

  • Origin:
  • Superior head: Infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone
  • Inferior head: Lateral surface of the lateral pterygoid plate of the sphenoid bone
  • Insertion:
  • Superior head: Articular disc and capsule of the TMJ
  • Inferior head: Pterygoid fovea on the anterior surface of the neck of the mandibular condyle
  • Action:
  • Bilateral: Depression (opening) of the mandible, protraction (protrusion) of the mandible
  • Unilateral: Contralateral lateral deviation (excursion) of the mandible
  • Superior head: Stabilizes the disc during jaw closing; pulls the disc anteriorly during opening
  • Innervation: Lateral pterygoid nerve — a branch of the mandibular division of the trigeminal nerve (CN V3)

Palpation Guide

  • Client position: Supine or seated with mouth slightly open.
  • Landmark sequence:
  1. The lateral pterygoid is deep and not directly palpable externally. It lies deep to the mandibular ramus, in the infratemporal fossa.
  2. Intraoral approach: With a gloved hand, place your index finger inside the mouth along the buccal surface of the upper teeth. Slide posteriorly and superiorly, past the last molar, toward the space behind the maxillary tuberosity. The lateral pterygoid lies in this region, but only the inferior head is partially accessible.
  3. External approximation: Place your fingertip just anterior to the TMJ (in front of the tragus), deep to the posterior border of the masseter. Ask the client to open the jaw — you may feel the condyle translate forward as the lateral pterygoid contracts. This is an indirect palpation.
  • Tissue feel: The lateral pterygoid is largely inaccessible to direct palpation. When contacted intraorally, it is deep, tender, and feels like firm tissue behind the maxillary tuberosity. Clients often report significant tenderness even with light contact.
  • Confirmation test: Ask the client to open the jaw or protract the mandible against light resistance. The lateral pterygoid is the prime mover for both. You may feel increased tension in the intraoral palpation position.
  • Common errors:
  • Claiming to directly palpate the lateral pterygoid externally — it lies behind the ramus and is not accessible from outside the mouth.
  • Confusing the medial pterygoid with the lateral pterygoid during intraoral work — the medial pterygoid is more medial and inferior, on the internal surface of the ramus.
  • Applying excessive pressure intraorally — the area is highly sensitive and clients tolerate very little pressure here.

Trigger Point Referral

  • Common TrP locations: The inferior head is the typical site — deep in the infratemporal fossa, behind the maxillary tuberosity. The superior head, which attaches to the disc, develops TrPs that contribute to disc dysfunction rather than referred pain.
  • Referral pattern: Refers to the TMJ region itself and deep into the cheek (zygomatic region). May also refer into the maxillary region, mimicking maxillary sinus pain.
  • Clinical significance: The superior head attaches directly to the TMJ disc. Hypertonicity or TrPs in the superior head pull the disc anteriorly, producing the anterior disc displacement that causes clicking on jaw opening. This is the mechanical link between muscular dysfunction and internal TMJ derangement.

Trigger point referral diagram — coming soon

Image coming soon. For visual reference, see [Lateral Pterygoid at TriggerPoints.net](http://www.triggerpoints.net/muscle/lateral-pterygoid).

Clinical Notes

Innervation significance:
  • Innervated by CN V3 along with all other muscles of mastication. The lateral pterygoid's unique role as the only opener means that its dysfunction directly affects jaw dynamics — when it goes into spasm, the jaw locks in either the open or closed position depending on the context.
Common conditions:
  • The most directly involved muscle in conditions/tmj-dysfunction with disc displacement. The superior head's attachment to the disc means that hypertonicity pulls the disc anteriorly relative to the condyle. This produces:
  • Disc displacement with reduction: The click on opening occurs when the condyle rides over the displaced disc and reduces to its normal position.
  • Disc displacement without reduction: The disc remains displaced and the jaw cannot fully open — this is the "locked jaw" presentation.
  • Involved in jaw deviation — unilateral lateral pterygoid dysfunction causes the jaw to deviate to the contralateral side during opening.
  • Contributes to conditions/tension-headache through TMJ-related referral patterns.
What you'll typically find:
  • In clients with TMJ clicking, the lateral pterygoid is almost always involved. The click occurs during the opening phase as the condyle translates forward and rides over the anteriorly displaced disc.
  • Direct assessment is limited because the muscle is largely inaccessible. Clinical reasoning relies on the pattern of TMJ dysfunction: if there is anterior disc displacement (clicking on opening, deviation, limited opening), the lateral pterygoid is implicated.
  • Clients with chronic jaw clenching may have lateral pterygoid spasm as a secondary finding — the muscle is overworked during the eccentric deceleration of jaw closing.
Treatment effects:
  • Intraoral release of the lateral pterygoid (where accessible) requires very gentle, sustained pressure. The area is extremely sensitive. Use minimal force (a few ounces of pressure) and hold for 30–60 seconds. The client will likely report significant tenderness.
  • External TMJ mobilization can indirectly affect the lateral pterygoid — sustained distraction of the mandibular condyle (inferior glide) can reduce tension on the superior head.
  • Post-treatment, TMJ clicking may reduce or change character. Full resolution of disc displacement typically requires multiple sessions.
Cautions:
  • The maxillary artery runs through the infratemporal fossa in close proximity to the lateral pterygoid. Deep intraoral pressure in this region risks compressing the artery.
  • The area is highly sensitive — even light pressure produces significant discomfort. Use the minimum pressure necessary and maintain clear communication with the client.
  • The lateral pterygoid is not directly treatable with standard external massage — claims of external lateral pterygoid release are anatomically unsupported.
Clinical pearl:
  • If a client has TMJ clicking that gets progressively worse and the jaw occasionally "catches" or "locks" momentarily before clicking open, the disc displacement is progressing. The superior head of the lateral pterygoid is pulling the disc further anterior. Early intervention with intraoral lateral pterygoid work and balanced treatment of all masticatory muscles gives the best chance of preventing progression to locked jaw (displacement without reduction).

Assessment

Manual muscle testing:
  • Jaw depression (opening): Client seated. Ask the client to open the jaw against your resistance under the chin. The lateral pterygoid is the primary mover.
  • Mandibular protraction: Client seated. Ask the client to push the lower jaw forward against your resistance.
Stretch test:
  • Mandibular retraction: Client seated. Gentle retraction (pulling the chin backward) stretches the lateral pterygoid. Compare ease of retraction bilaterally.
Related special orthopedic tests:
  • TMJ palpation with opening/closing — note the timing, volume, and character of any click
  • Jaw deviation on opening — deviation toward the contralateral side suggests ipsilateral lateral pterygoid dysfunction

Muscle Groups

Muscles of mastication (anatomical): Jaw depressors (openers) (functional): Mandibular protractors (functional): Trigeminal nerve — mandibular division (CN V3) group (innervation):

Related Muscles

Synergists for jaw depression: Antagonists: Clinically related:
  • anatomy/muscles/masseter — the two muscles must be balanced for normal TMJ disc tracking; masseter hypertonicity without matching lateral pterygoid function produces condylar compression

Key Takeaways

  • The only muscle of mastication that opens the jaw — its superior head attaches directly to the TMJ disc, making it the mechanical link in anterior disc displacement.
  • Not directly palpable externally — intraoral access is limited and requires very gentle technique.
  • TMJ clicking that progressively worsens with intermittent catching suggests advancing disc displacement driven by superior head hypertonicity.

Related

Sources

  • Travell, J. G., & Simons, D. G. (1999). Myofascial pain and dysfunction: The trigger point manual (Vol. 1, 2nd ed.). Williams & Wilkins. (pp. 371–394)
  • Biel, A. (2014). Trail guide to the body (5th ed.). Books of Discovery.
  • Vizniak, N. A. (2010). Muscle manual. Professional Health Systems.
  • Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2023). Clinically oriented anatomy (9th ed.). Wolters Kluwer. (Ch. 7: Head)
  • Rattray, F., & Ludwig, L. (2000). Clinical massage therapy: Understanding, assessing and treating over 70 conditions. Talus Incorporated.
  • Magee, D. J., & Manske, R. C. (2021). Orthopedic physical assessment (7th ed.). Elsevier.
← All Muscles