The hypertrophied temporalis and masseter muscles give a muscular shaped and bulky contour to the face.

Botulinum neurotoxin injection methods are commonly used for facial contouring; however, adverse effects have been reported owing to a lack of delicate anatomical information. The anatomical considerations when injecting botulinum neurotoxin into the temporalis and masseter muscles were reviewed in the present study.

Current knowledge on the localization of the botulinum neurotoxin injection point with more recent anatomical dissection and modified Sihler staining procedures was assessed. The authors found that, for the muscles, the injection point can be more precisely demarcated.

Optimal injection sites are presented for the temporalis and masseter muscles, and the injection technique is suggested. The authors propose the optimal injection sites in relation to external anatomical landmarks for the frequently injected muscles of the face to facilitate the efficiency of botulinum neurotoxin injections.

In addition, these guidelines would aid in more precise practice without the adverse effects of botulinum neurotoxin.