Background: The inferior temporal septum (ITS) is a fibrous adhesion between the superficial temporal fascia and the superficial layer of the deep temporal fascia. This study identified detailed the anatomical relationship between the ITS and the temporal branch of the facial nerve (TBFN) for facial nerve preservation during temple interventions. Methods: Among 33 Korean cadavers, 43 sides of TBFNs in temporal regions were dissected after identifying the ITS between the superficial temporal fascia and superficial layer of the deep temporal fascia through blunt dissection. The topography of the ITS and TBFN were investigated with reference to several facial landmarks. Regional relationships with the ITS and TBFN within the temporal fascial layers were histologically defined from five specimens. Results: At the level of the inferior orbital margin by the tragion, the mean distances from the lateral canthus to the anterior and posterior branches of the TBFN were 5 and 6.2 cm, respectively. At the lateral canthus level, the mean distance from the lateral canthus to the posterior branch of the TBFN was similar to that to the ITS, at 5.5 cm. At the superior orbital margin level, the posterior branch of the TBFN ran cranial to the ITS adjacent to the frontotemporal region. The TBFN ran through the subsuperficial temporal fascia layer and the nerve fibers located cranially, and within the ITS meshwork in the upper temporal compartment. Conclusion: The area of caution during superficial temporal fascia interventions related to the TBFN was clearly identified in the upper temporal compartment, which is known to lack important structures.

The aim of this study was to identify the three-dimensional topography of the sphenoid door jamb (SDJ) in the lateral orbital wall and to propose navigational guidelines for safe deep lateral decompression using surgical landmarks. The 120 orbits and SDJs of 60 subjects were three-dimensionally reconstructed using Mimics software. The mean volumes of the orbit and SDJ were 24.3 mm(3) and 2.0 mm(3), respectively. The mean distances from the lateral orbital margin (LOM) to the anterior and posterior margins of the SDJ were 13.2 and 36.3 mm, respectively. The mean distances from the superior orbital fissure to the LOM and to the posterior margin of the SDJ were 40.2 mm and 4.6 mm, respectively. The mean distances from the inferior orbital fissure (IOF) to the anterior and posterior margins of the SDJ were 3.8 mm and 20.5 mm, respectively. In the superior approach of the orbit, it can be predicted that the area up to 3 cm posterior from the LOM is safe, while 1 cm posterior from the safe zone could be a dangerous zone. In the inferior approach of the orbit, the safe area will be about 1 cm posterior from the anterior tip of the IOF, and the area up to 1 cm posterior from the safe zone should be approached with extreme care.

The facial nerve is the seventh cranial nerve, and its temporal branch (TBFN) innervates the frontalis muscle. Peripheral nerve disorders involving the facial nerve can lead to facial palsy, for which a common non-invasive treatment approach is to inject a chemodenervation agent such as botulinum toxin (BoNT). The purpose of this study was to provide anatomical suggestions for BoNT injection sites in the frontalis muscle based on the intramuscular innervation pattern of the TBFN as identified objectively using Sihler’s staining. Nineteen hemifaces containing the TBFN and the frontalis muscle were harvested from 15 embalmed cadavers according to facial landmarks. The frontalis muscle was divided into 16 areas to identify the prevalence rates of distal nerve endings and the arborization pattern of the TBFN after applying Sihler’s staining. Distal nerve endings of the TBFN were most commonly found in area B2 (17 of 19 specimens, 89.5%), followed by in area B3 (n = 15, 78.9%). No distal nerve ending was observed in area A1. Two types of the arborization pattern of the TBFN were observed. We propose four BoNT injection sites based on the intramuscular innervation pattern of the TBFN in the frontalis muscle as identified using Sihler’s staining.

Lee SH, et al. Anat Cell Biol. 2020 Jan;53:e2. https://doi.org/10.5115/acb.19.189

The purpose of this study was to elucidate the topography of the corrugator supercilii muscle (CSM) relative to the eyebrow with the aim of providing topographical guidance for botulinum toxin type A (BTX-A) injections in the East Asian population. Thirty-six hemifaces of 18 donated bodies for anatomical studies were dissected. Prior to dissection, four specific points on the eyebrow were marked to serve as reference points. A superimposition method for analyzing the position of the CSM relative to the eyebrow involved overlaying an image showing the dissected muscle onto a pre-existing image that contained reference lines indicating the eyebrow landmarks. The CSM almost overlaps the eyebrow at its medial end. Significantly, the central part of the CSM’s width was positioned just above the upper point of the eyebrow, being closely aligned with the midpupillary line. There was minimal overlap of the CSM beyond the midpupillary line on the lateral side, indicating that this muscle becomes relatively scarce or less distinct as it extends laterally from the midpupillary line. For effectively targeting the CSM, it is recommended to inject BTX-A precisely at the center of the medial end of the eyebrow just above the midpupillary line.