Innervation of the Temporalis Muscle: Anatomical Study and Clinical Implications in Smile Reconstruction Techniques.

Abstract

Objectives: The temporalis muscle flap is regaining popularity for facial reanimation since recent modifications have improved its efficacy as a single-stage technique. Nevertheless, in all these procedures, the deep temporal nerve innervating the muscle is not visualized. Thus, the purpose of this anatomical study is to track the deep temporal nerve's course and provide a visual guide of it.

Methods: Eighteen hemifacial cadaveric specimens were dissected to trace the deep temporal nerve's course from its origin to its entry point in the temporalis muscle. This was performed without disturbing the native course of the deep temporal nerve in relation to the undetached temporalis muscle. Multiple craniofacial osteotomies were performed for exposure while maintaining the spatial relationship of the deep temporal nerve to the muscle.

Results: In 14 specimens (78%), the deep temporal nerve arose from the mandibular nerve. In four specimens (22%), it originated from the maxillary nerve. The deep temporal nerve was approximately 1.7 cm in length from its origin to its point of entry into the muscle. It entered at an average of 0.91 cm directly above the tip of the coronoid process.

Conclusions: With respect to mobilizing temporalis muscle flap, the high origin of the deep temporal nerve from the maxillary nerve may impact the descent of muscle. Because of the proximity of the nerve entry point to the temporalis tendon, special care must be taken when detaching the tendon from the coronoid process to avoid nerve traction and avulsion. The maxillary nerve is mixed with both sensory and motor components in some cases, which is in contrast to the established concept that it is purely sensory.