Clinical anatomy and palpability of the inferior lateral pterygoid muscle

Statement of problem. The intraoral palpation technique of the inferior bel ly of the inferior lateral pterygoid (ILP) muscle is a standard diagnostic: examination method for temporomandibular joint dysfunction syndrome, altho ugh different studies have revealed inconsistent results. Purpose. This study assessed the feasibility of the ILP muscle palpation by a simulated clinical setting. Material and methods. Three dentists performed a bilateral palpation of the ILP muscle in 53 fresh and unfixed human cadavers and decided whether the muscle was palpable or unpalpable. In a second step, it was obscured throug h the dissected infratemporal fossa, whether the examiner's finger did or d id not touch the ILP muscle by simulating the performed palpation. Palpator y findings were supplemented by 1-dimensional measurements for determinatio n of topographic relations of the ILP muscle within the infratemporal fossa . For statistical analysis, sensitivity, specificity, and negative and posi tive predictive values of the palpation technique were calculated. Interexa miner agreement was estimated with the kappa value. Results. In 86 of 106 dissected specimens, a superficial fascicle of the me dial pterygoid muscle was found in direct proximity to the ILP muscle. In t hese cases, a residual distance of 7.8 +/- 3.2 mm remained between the ILP muscle and buccinator fascia indented by the tip of the examiner's finger. In 10 of 20 specimens with an absent superficial fascicle, the finger was a ble to reach the ILP muscle. Conclusion. It is recommended that the ILP muscle palpation technique shoul d no longer be considered as a standard clinical procedure because it is ne arly impossible to palpate the ILP muscle anatomically and because the risk of false-positive findings (by palpation of the medial pterygoid muscle) i s high.