[Craniotomy and the temporal branch of the facial nerve]

The surgical anatomy of the temporal branch of the facial nerve was studied in the anatomical laboratory. The temporal branch divides into an anterior, middle (frontal), and a posterior ramus after it pierces the parotid fascia. The anterior ramus innervates orbicularis oculi and corrugator supercilii muscles; the middle branch is for the ipsilateral frontalis muscle. The posterior branch innervates the anterior and superior auricular and tragus muscles. Below the zygomatic arch, the temporal branch of the facial nerve is located in the subcutaneous tissue. Above the arch, it continues in the subgaleal space with the superficial temporal fascia deeply. The terminal twigs of the temporal branch penetrate the galea to reach their target muscles that are all located superficial to the galea. There is a significant variability in the course of the temporal branch of the facial nerve. Occasionally, the terminal twigs of the middle ramus may penetrate superficial layer of superficial temporal fascia and run in the intrafascial fat pad before entering the frontalis muscle. There are four available operative techniques in this anatomical location. The subgaleal dissection of a temporofrontal scalp flap is associated with a high incidence of postoperative palsy of the temporal branch of the facial nerve and cosmetically bothersome results. Reflecting the scalp and temporalis muscle together as a single layer is the safest procedure. Unfortunately, this technique can not be used for the transzygomatic approaches and the bulky temporalis muscle may compromise basal exposure in the pterional route. Third technique was described and propagated by Yasargil. He proposed a subgaleal dissection up to the anterior one-fourth of the temporalis muscle where the dissection has to be deepened between the two layers of the superficial temporal fascia (in the interfascial fat pad). This approach may also infrequently injure the temporal branch in case of anatomical variation. The last available operative technique raises the superficial temporal fascia together with the scalp.