Topographic Localization of Nerve to Masseter Muscle to determine the Primary Nerve- Muscle Relation, an Aid to Facial Sculpting Techniques

Abstract

Background. The masseteric nerve is a suitable target as a motor nerve donor for facial reanimation surgeries and botulinum toxin injection in case of hypertrophy of masseter muscle. In this context determining the topographical location of the motor point (MP) of masseter muscle with reference to standard anatomical landmarks becomes significant. Methods. Eleven formalin-fixed cadavers were dissected meticulously. After identifying the MP of the masseteric muscle, its distance from the preauricular point, the midpoint of the orbitomeatal line and angle of mouth were defined. The thickness of the masseter muscle was determined. Results. The mean distance of the MP from the preauricular point, the midpoint of the orbitomeatal line and the angle of mouth were 5.59 cm, 3.43 cm and 5.14 cm respectively on the right and 5.11 cm, 3.32 cm and 5.36 cm respectively on the left side. The mean thickness of masseter muscle was 5.24 cm on right and 5.32 cm on the left side. Conclusions. The MP of masseter muscle lies at a point which is almost equidistant from the preauricular point and angle of mouth but in more proximity to the orbitomeatal line. Its entry into the masseter is on an average of 5.28 cm from the surface.