Debate on the morphological variability of the lateral pterygoid muscle
A critical review arguing that the lateral pterygoid muscle cannot be reduced to a single fixed two-headed template: its internal structure, head number, origins, insertions, and accessory muscular relations are substantially more variable than many standard descriptions imply.
There is no one-size-fits-all anatomical pattern for the LPM.
The review concludes that the lateral pterygoid muscle is structurally and functionally heterogeneous. Personalized anatomical assessment—preferably with modern imaging when possible—is therefore more defensible than reliance on a rigid standard template.
Why the standard description is insufficient
Traditional anatomy often describes the LPM as having superior and inferior heads. The paper reviews evidence showing that head number, bundle arrangement, pennation, and topographic organization can depart substantially from this simplified model.
Classical heads
Superior and inferior heads remain the usual teaching framework.
Possible heads
Middle or medial additional heads and unusual bundle configurations have been reported.
Pennation
Internal architecture may be penniform and functionally heterogeneous.
Insertions
Attachments to the mandibular condyle and TMJ disc are themselves variable.
The anatomy varies along several axes at once
The paper does not treat variability as a single anomaly category. Instead, it assembles a broader spectrum of structural variables that jointly shape how the muscle should be interpreted.
Head number and internal bundles
Beyond the superior and inferior heads, additional heads and differently partitioned bundles have been described, challenging the idea that the LPM is always organized in the same way.
Origins from the sphenoid and pterygoid plate
Variations in the greater wing of the sphenoid, the lateral pterygoid plate, or extensions from it can enlarge or modify the area of origin.
Insertions to condyle and disc
The muscle may insert variably into the mandibular condyle and temporomandibular joint disc, and aberrant bundles may attach outside the mandibular notch.
Accessory muscles and neighbouring variants
Rarely encountered muscles—including the pterygoideus proprius, pterygospinosus, pterygofacialis, pterygotemporal, maxillomandibularis, and sphenomandibular muscle—expand the regional diversity and may affect interpretation.
From textbook template to individualized morphology
This simplified map summarizes the paper’s logic: each additional layer of variation reduces the usefulness of a rigid “two heads only” doctrine.
Why the debate is not merely terminological
If the LPM is structurally heterogeneous, functional interpretations, imaging analysis, temporomandibular-joint discussions, and therapeutic reasoning should avoid assuming a universal architecture.