The coronoidectomy approach is a known but still quite underestimated procedure focused on the removal of the coronoid process of the mandible. Most cases related to outer-joint-related factors causing limited mouth opening (LMO) might be related to a great variety of factors. Quite often, patients suffer a lot from the inability to fully open their mouths. During this time, they are scheduled for limitless conservative, pharmacological, and diagnostic steps to estimate the cause of LMO and increase patients’ mouth opening. In those cases, a diagnostic coronoidectomy might be useful to estimate the potential cause of such a problem. On the other hand, a prophylactic coronoidectomy is still quite randomly described in the world literature and mostly selected for a limited number of special cases. Herein, we would like to present a special issue of the major trauma in the temporal bone, middle cranial fossa, and zygomatico-malar area that resulted in temporal muscle contusion, scarring, and later contraction. A hemicoronal approach was performed to stabilize the fractures of the left zygomatico-orbital area with titanium osteosynthesis plates and screws. Over time, the LMO increased. All temporomandibular joint (TMJ)-related pathologies have been excluded. In the second week, the post-op patient was only able to open his mouth at 12 mm. Temporal muscle injury over time caused major contractions, greatly influencing LMO. The following paper describes the influence of temporal muscle trauma on limited mouth opening and indications for simultaneously performing coronoidectomy during stable bone osteosynthesis. Keywords: cranio-facial injury; coronoidectomy; titanium plates and screws; stable bone osteosynthesis; temporal muscle contraction