Medial and lateral pterygoid muscles: anatomy
Quick facts
- Location
- In the infratemporal fossa, inside the mandibular ramus, in a deep plane.
- Lateral pterygoid
- Two heads running from the greater wing of the sphenoid and the lateral plate of the pterygoid process to the neck of the condyle, the disc and the TMJ capsule.
- Medial pterygoid
- Runs from the medial surface of the lateral pterygoid plate and the maxillary tuberosity to the inner surface of the mandibular angle.
- Innervation
- Branches of the mandibular nerve, a division of the trigeminal nerve.
- Relevance in HOF
- They are part of chewing and bruxism, but they are deep and not part of aesthetic contour treatment.
The pterygoid muscles are two muscles of mastication, medial and lateral, located on each side in the infratemporal fossa, inside the ramus of the mandible. The lateral pterygoid pulls the condyle forward and takes part in opening the mouth and in side-to-side movements. The medial pterygoid helps close the mouth and works with the masseter like a sling around the angle of the mandible. Both are innervated by the mandibular nerve, a division of the trigeminal.
Origin, insertion and function
| Muscle | Origin | Insertion | Main action |
|---|---|---|---|
| Lateral pterygoid, superior head | Infratemporal surface of the greater wing of the sphenoid | TMJ capsule and disc and neck of the condyle | Stabilizes the disc and condyle, especially in closing |
| Lateral pterygoid, inferior head | Lateral surface of the lateral plate of the pterygoid process | Pterygoid fovea, on the neck of the condyle | Protrusion, mouth opening and lateral movement to the opposite side |
| Medial pterygoid, deep head | Medial surface of the lateral plate of the pterygoid process | Inner surface of the angle and ramus of the mandible | Elevation (closing), protrusion and lateral movement |
| Medial pterygoid, superficial head | Maxillary tuberosity and pyramidal process of the palatine bone | Same insertion as the deep head | Same actions |
The division of functions between the heads of the lateral pterygoid is a topic of debate in the literature, but the muscle's role in moving the condyle forward is agreed.
How do they relate to the masseter and temporalis?
The masseter, outside the ramus, and the medial pterygoid, inside it, form a sling that supports the angle of the mandible and elevates the jaw. The temporalis completes the group of elevators. The lateral pterygoid is the only muscle of mastication with a main role in opening and protrusion. For that reason, the balance among the four muscles defines the mechanics of chewing and of the TMJ.
Why do they matter in HOF?
- Bruxism and TMD: the pterygoids appear in complaints of bruxism, locking and TMJ pain. The topic of toxin in this area is in botulinum toxin for bruxism.
- Face contour: slimming of the lower third with toxin is done in the masseter, which is superficial. The pterygoids are deep and are not part of aesthetic contour treatment. See botulinum toxin in the masseter.
- Compensation: when the masseter is relaxed, the other muscles of mastication keep working, which helps explain why chewing strength is kept in most cases.
How do they show up in the assessment?
- Mouth opening: deviation to one side can indicate imbalance between the lateral pterygoids or a TMJ change.
- Lateral and protrusive movements: limitation or pain suggests joint involvement.
- TMJ noises: clicking and crepitus call for specialist assessment.
- Tooth wear and pain on waking: signs associated with bruxism.
Also called: pterygoids, medial and lateral pterygoid, internal and external pterygoid.
Frequently asked questions
Is the lateral pterygoid related to bruxism?
Yes. The pterygoids take part in the protrusive and lateral movements of the jaw and can be overactive in bruxism and TMJ disorders. Diagnosing and treating these conditions is up to the professional who manages TMD.