Lateral pterygoid muscle

Last revised by William Howden on 12 Apr 2023

The lateral pterygoid muscle, also known as pterygoideus externus or external pterygoid muscle, is one of the muscles of mastication

The lateral pterygoid is a short and thick muscle with a somewhat conical form. It extends almost horizontally, posteriorly, and laterally between the infratemporal fossa and the condyle of the mandible. It has two heads: an upper (superior) and a lower (inferior). 

The superior part arises from the lower part of the lateral surface of the greater wing of the sphenoid bone and the infratemporal crest. It inserts into the temporomandibular joint capsule and the temperomandibular disc.

The inferior part arises from the lateral surface of the lateral pterygoid plate and inserts into a depression in front of the neck of the condyle of the mandible, the pterygoid fovea 1.

The muscle is supplied by the paired nerves to lateral pterygoid (one for each head), which arise deep to the muscle from the anterior division of the mandibular nerve (CN V3).

The superior part is active during retrusion (opposite of protrusion) and ipsilateral jaw movement. It is also essential in pulling the capsule and disc forward during mouth opening, thereby maintaining normal relationship between the condyle of the mandible and the disc of the tempoeromandibular joint.

The inferior part is responsible for opening of the mouth, protrusion, and contralateral jaw movement.

Hyperactivity of the lateral pterygoid muscle has been described in temperomandibular joint internal derangement, especially with longstanding anterior displacement of the disc without recapture. Thickening of the tendon (inferior part) can give rise to the "double disc sign".

Anatomical variants of the lateral pterygoid include:

  • fusion with temporalis or digastric muscle

  • variation in number of heads

  • variation in number of insertions

    • three insertion sites: articular disc, TMJ capsule, condyle of the mandible

    • single insertion site at the condyle only

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Cases and figures

  • Figure 1
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  • Figure 2: muscles of mastication
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  • Figure 3
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  • Figure 4: pterygoid muscles (Gray's illustration)
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