INNERVATION PATTERN OF THE TEMPORALIS MUSCLE

The purpose of this article is to describe the neural anatomy of the t emporalis muscle as dissected along the intramuscular temporal fascial plane. This sagittal plane is a natural cleavage plane of the muscle, which is explored along with its relationship to the deep temporal ne rve. Eight temporalis muscle specimens were removed in their entirety from 8 preserved cadavers. The muscles were selected based on whether they were grossly intact prior to procurement for processing. The musc le specimens were then processed over a 3-month period using Sihler's staining technique. Muscle dissection was performed along the intramus cular fascial plane under an operating microscope, taking care to pres erve the underlying nerve and arterial anatomy. Dissections demonstrat ed an anterior and posterior division of the deep temporal nerve runni ng within the deep portion of the muscle below the intramuscular fasci al plane. This fascial layer provided a natural dissection plane to ex pose and evaluate the underlying nerve and arterial anatomy. In all sp ecimens the deep temporal artery originated with the anterior temporal nerve and then branched into an anterior and posterior division. The innervation density and nerve caliber of the anterior portion of the m uscle was much greater than that of the posterior, correlating with a greater anterior muscle bulk. This may have implications in difference s in fiber type and functional regionalization of the muscle. The resu lts of this anatomic study support the finding of an anterior and post erior division of the deep temporal nerve within the deep portion of t he temporalis muscle. In addition, differences in the innervation dens ity and muscle bulk lend credence to the possibility of regional muscl e specialization. The natural cleavage plane of the intramuscular temp oral fascia may have clinical ramifications for temporalis myofascial flaps while preserving the underlying neural anatomy to allow for norm al residual temporalis muscle function.